Oldest human remains from Puerto Rico reveal a complex cultural landscape since 1800BC

Persistent burial practices over many centuries challenge simplistic assumptions about ancient culture

Peer-Reviewed Publication

PLOS

 

IMAGE: VIEW ACROSS BOQUERÓN BAY, CABO ROJO, PUERTO RICO, WITH THE ORTIZ SITE IN THE DISTANCE. view more 

CREDIT: WILLIAM J. PESTLE, CC-BY 4.0 (HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)

The earliest inhabitants of Puerto Rico might have used common burial sites and mortuary practices across many centuries, according to a study published April 26, 2023, in the open-access journal PLOS ONE by William J. Pestle of the University of Miami, Florida and colleagues.

Puerto Rico was inhabited by people for several thousand years prior to the Ceramic Age, but little is known about these earliest inhabitants due to a paucity of evidence and research, with only 20 ancient individuals reported from this time period. In this study, Pestle and colleagues describe five adult individuals from burials at the Ortiz site in Cabo Rojo, southwestern Puerto Rico, representing a substantial addition to archaeological information about this time period.

Radiocarbon dating of the remains yielded ages as old as 1800BC and as young as 800BC, thus including the oldest directly dated human remains from Puerto Rico and representing as much as 1,000 years of burials at the Ortiz site. The mortuary practices, including the positioning of the bodies and the associated grave goods, are similar to other early sites, indicating standard burial practices over many centuries. In addition, Strontium isotope analysis also indicates that these buried individuals were born in different nearby geographical locales. Thus, the Ortiz site might have held cultural significance as a common mortuary space for various local communities.

The authors caution that it is difficult to draw broad conclusions from limited evidence, but these results hint at a long history of persistent and formalized use of a common site over centuries. The earliest inhabitants of Puerto Rico have been traditionally interpreted in a simplistic fashion, but the results from this study and hopefully future studies shed light on what was likely a more vibrant and varied cultural landscape than previously appreciated.

The authors add: “This study assiduously documents the oldest dated burials from the island of Puerto Rico and provides detailed scientific and cultural insights into the lives of some of the earliest people to inhabit that island. We hope that this work contributes to the ongoing re-framing of our understanding of the deep past of Puerto Rico and the Caribbean.”

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In your coverage please use this URL to provide access to the freely available article in PLOS ONE: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0284291

Citation: Pestle WJ, Perez EM, Koski-Karell D (2023) Reconsidering the lives of the earliest Puerto Ricans: Mortuary Archaeology and bioarchaeology of the Ortiz site. PLoS ONE 18(4): e0284291. https://doi.org/10.1371/journal.pone.0284291

Author Countries: USA

Funding: The National Institute of Archaeology and the Anthropological Research Council both provided funding to WJP. The principal of the National Institute of Archaeology (DKK) was involved in the data collection (excavation) of the materials presented in this research.

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JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0284291 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Reconsidering the lives of the earliest Puerto Ricans: Mortuary Archaeology and bioarchaeology of the Ortiz site

ARTICLE PUBLICATION DATE

26-Apr-2023

New findings indicate gene-edited rice might survive in Martian soil

U of A researchers presented an abstract at the 54th Lunar and Planetary Science Conference suggesting genetically modified rice could grow in the Martian regolith.

Reports and Proceedings

UNIVERSITY OF ARKANSAS

 

IMAGE: FROM LEFT: PETER JAMES GANN, ABHILASH RAMACHANDRAN, DOMINIC DHARWADKER, YHENI DWININGSIH AND VIBHA SRIVASTAVA. view more 

CREDIT: U OF A

Andy Weir’s bestselling 2011 book, The Martian, features botanist Mark Watney’s efforts to grow food on Mars after he becomes stranded there. While Watney’s initial efforts focus on growing potatoes, new research presented at the 54th Lunar and Planetary Science Conference by a team of interdisciplinary researchers from the U of A suggests future Martian botanists like Watney may have a better option: growing rice.

As outlined in the team’s abstract, Rice Can Grow and Survive in Martian Regolith with Challenges That Could be Overcome Through Control of Stress-Related Genes, one of the biggest challenges to growing food on Mars is the presence of perchlorate salts, which have been detected in the planet’s soil and are generally considered to be toxic for plants.

The team was able to simulate Martian soil using basaltic rich soil mined from the Mojave Desert, called the Mojave Mars Simulant, or MMS, which was developed by scientists from NASA and the Jet Propulsion Laboratory. 

The teams then grew three varieties of rice, including one wild-type and two gene-edited lines with genetic mutations that better enable them to respond to stress, such as drought, sugar starvation or salinity. These varieties were grown in the MMS, as well as a regular potted mix and a hybrid of the two. While plants were able to grow in the Martian simulant, they were not as developed as those grown in the potting soil and hybrid mix. Replacing just a quarter of the Martian simulant with potting soil resulted in improved development.

The team also experimented with the amount of perchlorate in the soil, finding that 3 grams per kilogram was the threshold beyond which nothing would grow, while mutant strains could still root in 1 gram per kilogram. 

Their findings suggest that there might be a way forward for genetically modified rice to find purchase in Martian soil.

Next steps will include experimenting with a newer Martian soil simulant called the Mars Global Simulant, as well as other rice strains that have increased tolerance for higher salt concentrations. An important part of the research will be determining to what degree perchlorate may be leeching into the plant from the soil. Farther down the road, the researchers would like to introduce rice into a closed habitat chamber and place it in a Mars simulation chamber that replicates the temperature and atmosphere of the planet.  

Whether humans ever colonize Mars, the team’s research could have applications here on Earth. Second author on the abstract, Abhilash Ramachandran, a post-doctoral fellow at the Arkansas Center for Space and Planetary Sciences, noted that he spoke with an Australian researcher from an area where the soil had high salinity, and saw their work as a potential way to grow food there. He added, “We could use Earth as a terrestrial analog before the seeds ever get sent to Mars.”

First author on the abstract, Peter James Gann, a doctoral student in cell and molecular biology, said that the project began when he met Ramachandran for coffee in the student union. “He was new here at the university, and we shared the things we were doing in our respective laboratories. Since he works on planetary science, and I specialize in cell and molecular biology, we decided to try out plants.”

They were joined by co-authors Yheni Dwiningsih, a post-doctoral associate in plant sciences; Dominic Dharwadker, an undergraduate student in the Honors College; and Vibha Srivastava, a professor in the Department of Crop, Soil and Environmental Sciences who has a joint appointment with the U of A System Division of Agriculture.

Gann, for one, is pleased with how his initial conversation with Ramachandran has turned out. “Relevant and interesting research can emanate from talking to strangers over a cup of coffee or a glass of beer,” he said, before adding: “Ain't that cool?” 

Tree diversity increases carbon storage, soil fertility in forests

Tree diversity increases carbon storage, soil fertility in forests

Peer-Reviewed Publication

UNIVERSITY OF ALBERTA

Keeping tree diversity intact in Canada’s many forests over the long term can help increase carbon capture and mitigate climate change, according to a new University of Alberta study. 

The study, published in Nature, is the first of its kind to show the sustained benefits of tree diversity on a large spatial scale, in terms of storing carbon and nitrogen in the soil. It reinforces the importance of biodiversity conservation in forests, says Xinli Chen, lead author on the paper and postdoctoral fellow in the Faculty of Agricultural, Life & Environmental Sciences. 

“Conserving tree diversity is a valuable tool in mitigating climate change, particularly in enhancing carbon storage in soil,” he says.

While it’s already been established that increasing soil carbon and nitrogen storage can help ease the effects of climate change and sustain soil fertility, stocks of both elements have declined substantially on a global level due to factors like forest fires, deforestation and land use change, he notes. Conserving and promoting tree diversity in forests can help increase the levels of soil carbon and nitrogen. 

The researchers analysed Canada’s National Forest Inventory database and used statistical modelling to provide new evidence of a link between greater tree diversity and higher soil carbon and nitrogen accumulation in natural forest ecosystems over decadal time scales, meaning a time scale over 10 years or longer. 

The work, done in collaboration with scientists from Canada, Japan and the United States, confirms collective findings from previous experiments. Specifically, the research showed that over the long term, evening out the numbers of tree species in natural forests would boost carbon and nitrogen in the organic soil layer by 30 and 43 per cent, respectively.

Hand in hand with that, increasing the variety of functional traits such as leaf nitrogen content and adult height of different tree species within a community could enhance carbon and nitrogen storage in the top mineral soil layer by 32 and 50 per cent.

The findings can “help guide growing efforts to use forests for carbon sequestration by protecting and enhancing the tree species diversity, which will at the same time benefit the productivity of forests today and in future,” Scott Chang notes.

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JOURNAL

Nature

DOI

10.1038/s41586-023-05941-9 

ARTICLE TITLE

Tree diversity increases decadal forest soil carbon and nitrogen accrual

ARTICLE PUBLICATION DATE

26-Apr-2023

Study: Tree diversity increases storage of carbon and nitrogen in forest soils, mitigating climate change

Peer-Reviewed Publication

UNIVERSITY OF MICHIGAN

Preserving the diversity of forests assures their productivity and potentially increases the accumulation of carbon and nitrogen in the soil, which helps to sustain soil fertility and mitigate global climate change.

That's the main takeaway from a new study that analyzed data from hundreds of plots in Canada's National Forest Inventory to investigate the relationship between tree diversity and changes in soil carbon and nitrogen in natural forests.

Numerous biodiversity-manipulation experiments have collectively suggested that higher tree diversity can lead to greater accumulation of carbon and nitrogen in forest soils. But the new study, published online April 26 in the journal Nature, is the first to show a similar outcome in natural forests, according to the authors.

The researchers used a statistical method called structural equation modeling to assess relationships between tree diversity and soil carbon and nitrogen accumulation. They found that increased tree diversity enhanced soil carbon storage by 30% to 32% and enhanced nitrogen storage by 42% to 50% on a decadal timescale.

"Our study, for the first time, shows the sustained benefits of tree diversity in storing soil carbon and nitrogen in natural forests," said study lead author Xinli Chen, a postdoctoral exchange fellow at U-M's Institute for Global Change Biology and a postdoctoral fellow at the University of Alberta.

"Our results highlight that promoting tree diversity not only increases productivity but also mitigates global climate change and reduces soil degradation. And the size of the diversity dividend is large. It reinforces the importance of biodiversity conservation in forests and will guide the growing efforts to use forests for carbon and nitrogen sequestration."

The researchers calculated changes in soil carbon and nitrogen storage over time by comparing data from two National Forest Inventory sample-plot censuses, one from 2000-2006 and the other from 2008-2017.

They quantified tree diversity as species richness, species evenness, and—on the basis of trees' functional traits—functional diversity.

Species richness is the number of tree species in a sample plot, while species evenness is a measure of the relative abundances of tree species. Functional diversity is the variety of functional traits—such as leaf nitrogen content and adult tree height—of tree species within a community.

The research team found that increasing species evenness from its minimum to its maximum value enhanced carbon storage in the organic soil layer by 30% and nitrogen storage by 42%. Increasing the functional diversity of trees to its maximum value enhanced carbon storage in the soil mineral layer by 32% and nitrogen storage by 50%.

"We find that greater tree diversity is associated with higher soil carbon and nitrogen accumulation, validating inferences from biodiversity-manipulation experiments," said study co-author Peter Reich, a forest ecologist and director of the Institute for Global Change Biology, which is part of U-M's School for Environment and Sustainability.

"A greater diversity of species translates into a mixture of different types of trees with different ways of acquiring and storing biomass—both in live trunks, roots, branches and leaves and in newly dead and decaying plant detritus on and in the soil."

Canada's National Forest Inventory database is based on a network of plots covering much of the country's landmass. The new study analyzed organic soil horizon samples from 361 plots and mineral soil horizon samples from 245 plots.

Those plots are home to various species of fir, maple, birch, spruce, pine, poplar, cedar and hemlock, among other tree types.

Forest soils play an important role in sequestering carbon extracted from planet-warming carbon dioxide gas during photosynthesis. Those soils store at least three times as much carbon as living plants do.

Nitrogen is an essential nutrient that drives carbon assimilation and plant growth in forest ecosystems. Plant diversity is rapidly declining globally, leading to the degradation of ecosystem function, including the function of soils.

The other authors of the Nature study are Anthony Taylor of the University of New Brunswick, Masumi Hisano of the University of Tokyo, Han Chen of Lakehead University, and Scott Chang of the University of Alberta and Zhejiang A&F University.

The research was supported by the Discovery Grants program of the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, the Ontario Research Fund, the Banting Postdoctoral Fellowship, and a grant from the U.S. National Science Foundation's Biological Integration Institutes.

Study abstract: Tree diversity increases decadal forest soil carbon and nitrogen accrual (DOI: 10.1038/s41586-023-05941-9.)

JOURNAL

Nature

DOI

10.1038/s41586-023-05941-9 

A UNION ISSUE

Parental leave for fathers can reduce sexist attitudes and gender bias

Peer-Reviewed Publication

RICE UNIVERSITY

Parental leave for fathers can decrease sexist attitudes and gender bias, according to new research from Rice University, Washington University in St. Louis, the University of Oxford and ETH Zurich.

“Fathers’ Leave Reduces Sexist Attitudes” will appear in an upcoming edition of the American Political Science Review. The researchers, including Jonathan Homola, an assistant professor of political science at Rice, were interested in how parental leave for nontraditional caregivers impacts individuals’ deeply ingrained attitudes about stereotypical gender roles and sexism — which can have adverse consequences when it comes to personal socioeconomic status and politics.

For the study, the researchers examined the attitudes of 1,362 new parents who were and were not directly affected by a policy reform in Estonia that tripled the amount of fathers’ leave time for babies born on or after July 1, 2020.

They found that families with fathers who received more parental leave saw an increase in belief in gender equality among both men and women. They also found that direct exposure to such policies raised support among women for pro-female policies such as requiring political parties to field more female candidates at the expense of male candidates. 

Indirect exposure to such policy reform didn’t change attitudes, the researchers found.

“We hope this study will show governments and organizations how direct exposure to progressive social policies can weaken sexist attitudes and be a practical and effective tool to reduce harmful biases,” he said. 

The paper was co-authored by Margit Tavits of Washington University in St. Louis, Petra Schleiter of the University of Oxford and Dalston Ward of ETH Zurich and Stanford University.

The study is available online at https://doi.org/10.1017/S0003055423000369.

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JOURNAL

American Political Science Review

SUBJECT OF RESEARCH

People

ARTICLE TITLE

“Fathers’ Leave Reduces Sexist Attitudes”

ARTICLE PUBLICATION DATE

26-Apr-2023

Links between pet ownership, stress, and loneliness during COVID-19 explored

Dog and cat owners reported feeling closer to their pets in the pandemic, though links with stress and loneliness appear complex

Peer-Reviewed Publication

PLOS

 

IMAGE: WORKING FROM HOME WITH PETS DURING COVID-19. view more 

CREDIT: HSIN-YI WENG, CC-BY 4.0 (HTTPS://CREATIVECOMMONS.ORG/LICENSES/BY/4.0/)

A new analysis suggests that, during the COVID-19 pandemic, US dog and cat owners became closer to their pets, and a complex relationship unfolded between pet ownership, stress, and loneliness. Niwako Ogata and Hsin-Yi Weng of Purdue University, US, and their colleague present these findings in the open-access journal PLOS ONE on April 26, 2023.

The COVID-19 pandemic provides a unique setting to explore pet-owner relationships and potential links between pet ownership and mental health. Several prior studies have investigated these topics in the context of the pandemic, but with limited scope.

Ogata and Weng conducted a series of surveys to capture the dynamics of dog and cat ownership in the USA – prior to the pandemic, during the lockdown period of April to June 2020, the reopening of September to December 2020, and a recovery period from January to December 2021. The surveys included questions related to participants’ closeness to the pet they felt most attached to, stress and loneliness levels, demographics, housing situation, personality, and other potentially relevant factors. Participants included 1,266 people with dogs and cats, 1,186 with only dogs, 1,128 with only cats, and 657 with no pets.

Statistical analysis of the survey responses showed that both dog and cat owners grew closer to their pets during the study period. However, links between pet ownership and mental health were more complex.

Compared to cat owners and participants without pets, dog owners experienced greater reduction of stress and loneliness during the reopening and recovery periods. Nonetheless, the researchers did not find statistically sound evidence that pet ownership eased participants’ stress and loneliness levels during the pandemic, and cat owners generally had more stress and loneliness than other participants. However, separating out different types of loneliness showed that, compared to non-pet owners, pet owners reported less loneliness specifically related to romantic relationships.

Further analysis suggests that the different results seen for dog versus cat owners may be explained by differences in the pet-owner relationship between these two groups.

The researchers will continue collecting similar data through 2023 in order to capture any further changes in pet-owner relationships, stress, and loneliness.

The authors add: “People felt closer toward their pets during the COVID-19 pandemic even though the pet ownership did not mitigate stress and loneliness. Dog ownership and cat ownership acted differently on mental health, but the difference between them could be partially explained away by the owner-pet relationship.”

#####

In your coverage please use this URL to provide access to the freely available article in PLOS ONE: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0284101

Citation: Ogata N, Weng H-Y, L. McV. Messam L (2023) Temporal patterns of owner-pet relationship, stress, and loneliness during the COVID-19 pandemic, and the effect of pet ownership on mental health: A longitudinal survey. PLoS ONE 18(4): e0284101. https://doi.org/10.1371/journal.pone.0284101

Author Countries: USA

Funding: This study, in whole, is funded by the Morris Animal Foundation (Grant number: D22FE-041, received by HYW; URL of the funder website: https://www.morrisanimalfoundation.org/). The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0284101 

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Temporal patterns of owner-pet relationship, stress, and loneliness during the COVID-19 pandemic, and the effect of pet ownership on mental health: A longitudinal survey

ARTICLE PUBLICATION DATE

26-Apr-2023

BCG vaccine does not protect against COVID-19 in healthcare workers

Peer-Reviewed Publication

MURDOCH CHILDRENS RESEARCH INSTITUTE

A world-leading international trial into the immune boosting benefits of the tuberculosis vaccine, BCG, has found it does not protect healthcare workers against COVID-19.

The BRACE trial, led by Murdoch Children’s Research Institute, to test whether the BCG vaccine could protect healthcare workers against SARS-CoV-2 in the first six months after vaccination found it didn’t reduce the risk of developing COVID-19 among those on the pandemic frontline.

BCG was originally developed to prevent tuberculosis and is still given to over 130 million babies worldwide each year for that purpose.

The BRACE trial was built on previous research, which showed BCG also boosted ‘front-line’ immunity in infants and protected against respiratory infections in adolescents and adults. It was hoped the vaccine could be repurposed to buy crucial time in a pandemic like COVID-19 until disease-specific vaccines were developed and tested.  

The research, published in the New England Journal of Medicine and based on the second stage of the BRACE randomised controlled trial, involved 3988 of the almost 7000 healthcare workers who signed up across 36 sites in Australia, the Netherlands, UK, Spain and Brazil. UMC Utrecht in the Netherlands, University of Exeter in the UK and the Oswaldo Cruz Foundation in Brazil helped to oversee the international arms of the trial.

The risk of symptomatic COVID-19 was 14.7 per cent in the BCG group and 12.3 per cent in the placebo group during the first six months after joining the trial. The research could not determine whether the vaccine reduced hospitalisations or death due to the low numbers of participants with severe COVID-19. 

Murdoch Children’s and the University of Melbourne Professor Nigel Curtis, Chief Principal Investigator of BRACE, said symptomatic COVID-19 being observed slightly more frequently in the BCG group might be explained by stronger immune responses induced by the vaccine.

“When we analysed the immune cells from our healthcare workers, we saw that the BCG vaccine altered the immune response to COVID-19,” he said.

“Symptoms reflect the immune system working hard to fight the virus. A stronger response induced by BCG could be beneficial in killing the virus more rapidly and protecting against progression to more severe disease. There was some evidence of this in trial participants over the age of 60, in whom COVID-19 symptoms were shorter in the BCG-vaccinated group.”

Professor Curtis said because COVID-19 vaccines had been developed and rolled out at lightning speed and healthcare workers prioritised, less participants were recruited than originally envisioned. As a result, lower case numbers meant the team was unable to investigate whether BCG protected against hospitalisation and death from COVID-19, he said.

A Murdoch Children’s led study, published in Clinical & Translational Immunology last year using blood samples from BRACE participants, also showed that the BCG vaccine did provide an immune response consistent with protection against severe COVID-19.

University of Exeter Professor John Campbell, who led the UK arm of BRACE, said the trial represented an important opportunity to test the potential of the BCG vaccine.

“The findings raise important questions about how BCG can modify the course of different viral illnesses and allows us to develop a fuller understanding of whether the vaccine can provide protection against a range of infections other than its main target, tuberculosis,” he said.

Oswaldo Cruz Foundation’s Dr Julio Croda said the majority of COVID-19 symptomatic cases were recorded in the Brazil trial arm.

“This demonstrates the high burden of the disease in Brazil during the entire pandemic,” he said. Although BCG does not protect against symptomatic COVID-19, we will also use the data to assess whether BCG protects healthcare workers for latent tuberculosis infection. An open question, especially for populations at high risk of acquiring the disease.”

Professor Curtis said trials of this size and complexity normally took about eight to 12 months to organise and recruit, but BRACE was able to start within three weeks due to the dedicated researchers and support teams at the Murdoch Children’s, together with generous philanthropic support.

“This trial highlights the importance of large-scale randomised controlled trials to test hypotheses and evaluate the effectiveness of new or repurposed drugs or vaccines,” he said. The importance of this was highlighted early in the pandemic by The Director General of the World Health Organization Tedros Ghebreyesus who stressed the need for the BCG vaccine to be given only in the context of clinical trials.”

Professor Curtis said trial data analysis was ongoing with further results on the effect of BCG expected later this year, including the impact of the vaccine on other infections, such as respiratory illnesses and the effect on COVID-19 vaccine responses. The trial team is also using blood samples collected from participants to discover biomarkers for COVID-19 risk.

BRACE trial donations included a $AU18 million grant from the Bill & Melinda Gates Foundation, $AU700,000 from Sarah and Lachlan Murdoch, $AU400,000 from The Royal Children’s Hospital Foundation, $AU1.5 million from The Minderoo Foundation, $AU200,000 from the South Australian Government and $AU250,000 from UK Peter Sowerby Foundation.

Publication: L.F. Pittet, N.L. Messina, F. Orsini, C.L. Moore, V. Abruzzo, S. Barry, R. Bonnici, M. Bonten, J. Campbell, J. Croda, M. Dalcolmo, K. Gardiner, G. Gell, S. Germano, A. Gomes‐Silva, C. Goodall, A. Gwee, T. Jamieson, B. Jardim, T.R. Kollmann, M.V.G. Lacerda, K.J. Lee, M. Lucas, D.J. Lynn, L. Manning, H.S. Marshall, E. McDonald, C.F. Munns, S. Nicholson, A. O’Connell, R.D. de Oliveira, S. Perlen, K.P. Perrett, C. Prat‐Aymerich, P.C. Richmond, J. Rodriguez‐Baño, G. dos Santos, P.V. da Silva, J.W. Teo, P. Villanueva, A. Warris, N.J. Wood, A. Davidson and N. Curtis for the BRACE Trial Consortium Group. ‘Randomized Trial of BCG Vaccine to Protect against Covid-19 in Health Care Workers,’ New England Journal of Medicine. DOI: 10.1056/NEJMoa2212616.

*The content of this communication is the sole responsibility of Murdoch Children’s and does not reflect the views of the NHMRC.

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JOURNAL

New England Journal of Medicine

DOI

10.1056/NEJMoa2212616 

METHOD OF RESEARCH

Randomized controlled/clinical trial

ARTICLE TITLE

Randomized Trial of BCG Vaccine to Protect against Covid-19 in Health Care Workers

ARTICLE PUBLICATION DATE

26-Apr-2023

TELL UCP THIS

Physical activity might help people with substance use disorders to reduce or cease their usage, with 75% of studies that evaluated it showing a relationship

BETTER A GYM MEMBERSHIP THAN FORCED DRUG REHAB 

PLOS

 

IMAGE: PEOPLE RUNNING OUTSIDE. view more 

CREDIT: COTTONBRO STUDIO, PEXELS, CC0 (HTTPS://CREATIVECOMMONS.ORG/PUBLICDOMAIN/ZERO/1.0/)

Article URL:  https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0283861

Article Title: Characteristics and impact of physical activity interventions during substance use disorder treatment excluding tobacco: A systematic review

Author Countries: Canada

Funding: F.P. was supported by a Fonds de Recherche du Québec-Santé doctoral fellowship and she received funding from CICC (Centre international de criminologie comparé) for the translation of the article. The two funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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JOURNAL

PLoS ONE

DOI

10.1371/journal.pone.0283861 

ARTICLE TITLE

Characteristics and impact of physical activity interventions during substance use disorder treatment excluding tobacco: A systematic review

ARTICLE PUBLICATION DATE

26-Apr-2023

Environmental context strongly

influences drug dependence, study

shows

Researchers observed the behavior and brain structures of mice after they developed addiction to cocaine, noting more agitation and brain activation associated with a specific environment.

Peer-Reviewed Publication

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO

Environmental context plays a major role in chemical dependence and addiction, inducing or reinforcing compulsive drug-seeking behavior, according to a study by researchers at three Brazilian institutions – the Federal University of São Paulo (UNIFESP), the Federal University of Espírito Santo (UFES) and the State University of Santa Cruz (UESC, Bahia) – in collaboration with a colleague at the University of Bristol in the United Kingdom.

The study analyzed the behavior and brain structures involved in cocaine dependence in an animal model. The findings are described in an article published in the journal Biomedicines. 

“It was surprising to see the force of the environment interfering in the context of dependence, which according to the scientific literature happens with various drugs that have abuse potential, whether licit or illicit, such as alcohol and opioids,” said Beatriz Monteiro Longo, professor of neurophysiology at UNIFESP’s Medical School (EPM) and principal investigator for the study.

FAPESP supported the study via two projects (2022/10520-0 and 2022/00249-8).

Female mice were used in light of their relative susceptibility to drugs and robust and rapid behavioral response, as established in the literature. Two experiments were conducted, involving cocaine injections in the home cages where the animals spent most of their time and in an open-field apparatus (widely used in experiments of the kind to assess exploratory behavior).

The experiments followed the same routine, starting with a three-day preparatory period in which all mice were taken to the open field for ten minutes per day. Baseline locomotor activity was measured on the third day of this habituation period. 

The animals were then divided into three groups. A control group (Sal-Sal) received a saline solution injection and after 5 minutes were exposed to the open field for 10 minutes. They then returned home and 2 hours later were again injected with saline solution. 

A second group (Coc-Sal) received an injection of cocaine and after 5 minutes were exposed to the open field for 10 minutes. They then returned home and 2 hours later were injected with saline solution. 

A third group (Sal-Coc) received a saline injection and after 5 minutes were exposed to the open field for 10 minutes. They then returned home and 2 hours later received an injection of cocaine.

Thus, the two groups given cocaine had the same pharmacological treatment: they received the same dose of the same drug. However, the psychostimulant effects of the drug were associated with the environment (open field) in one group but not in the other.

Interventions took place on alternate days for two weeks, considered long enough for the mice to develop dependence, which was defined as a persistent hyperlocomotion response.

In the first experiment, locomotion was analyzed again on the last day of cocaine treatment. The group that received cocaine for 15 intermittent days and was exposed to the open field (Coc-Sal) exhibited a significant increase in locomotor activity compared with the control group and with itself on the first day of cocaine injection, characterizing behavioral sensitization.

In the second experiment, the mice were kept in their cages without cocaine for ten days after the treatment. They were then challenged with cocaine and exposed to the open field for 10 minutes. As expected, locomotor activity increased in the two groups that had received the drug, but the animals with a history of open-field cocaine conditioning exhibited hyperlocomotion. According to the researchers, this agitation reflected the pharmacological effects of the drug and the effects of the environment in the behavioral expression phase, mimicking the craving for the drug in human addicts.

“To understand what this means in humans, simply think of someone who always drinks at the same bar and feels like going in for a beer whenever they’re walking past it,” Longo said.

What happens in the brain

In addition to characterizing behavioral sensitization to cocaine, the researchers also set out to identify the brain structures involved in the induction and expression phases of drug dependence by quantifying expression of c-Fos, a protein used as a marker of neuronal activity and intracellular alterations in addiction research. In this analysis, they used an innovative technique called stereology, which provides quantitative descriptions of the geometry of 3D structures from measurements made on 2D images. 

They detected activation of limbic regions associated with control of emotions and behavior. “We also observed that the brain regions with augmented activity were different in one phase and the other. In the first phase [induction], all the areas of the limbic system we investigated [the dorsomedial prefrontal cortex, nucleus accumbens core, basolateral amygdala and ventral tegmental area] were more activated, suggesting that these structures could be important to the development of dependence. In the expression phase [addiction], some were not activated,” said Renan Santos-Baldaia, professor of pharmacology at Nove de Julho University (UNINOVE) in Brazil and first author of the article, citing as an example the ventral tegmental area, which mediates the release of dopamine, an important neurotransmitter associated with the brain’s reward system. The brain regions analyzed appeared to participate to different extents in the two phases, he explained.

Treatment and public policy

The researchers expect the results of the study to open up possibilities for new therapeutic tools and interventions in the management of chemical dependence. “Given its complexity and the involvement of so many brain structures, as well as the impact of environmental factors, modulating addiction pharmacologically may not be the best strategy. Targeting the environment may actually be more effective,” Santos-Baldaia said.

“Moreover, because the environment influences addiction so significantly, can isolation in a rehabilitation clinic really be the best option? It removes addicts from the context of their dependence but entails a strong chance of relapse when they return to the old environment. Might it not be better to find some substitute for pharmacological pleasure?”

The findings underscore the need for public policies that improve environments lacking in cultural and leisure-related opportunities, such as the poor outlying neighborhoods of so many South American cities, to ensure that pharmacological pleasure is not the only option.

About São Paulo Research Foundation (FAPESP)

The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

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JOURNAL

Biomedicines

DOI

10.3390/biomedicines11020383 

ARTICLE TITLE

Distinctive Neuroanatomic Regions Involved in Cocaine-Induced Behavioral Sensitization in Mice