UNews - Mirela Ambeskovic

Male experimenters make female rats uneasy

caroline.zentner — Tue, 06 Sep 2022 20:00:30 +0000

Researchers at the ��Ѹ��Դ��߿�Ƭ of Lethbridge’s Canadian Centre for Behavioural Neuroscience (CCBN) have shown that the sex of an experimenter, a factor typically not accounted for in preclinical studies using rodents, could have an effect on study results. Their findings were recently published in Frontiers in Neuroscience.

Drs. Gerlinde Metz and Jamshid Faraji say study results call for improved standards.

Dr. Gerlinde Metz, along with Drs. Mirela Ambeskovic, Jamshid Faraji and others, compared the effects of male and female experimenters on male and female rats. In some situations, the experimenter was physically present and in others, unwashed T-shirts worn by the experimenters were placed in the room. Animals were handled by their male or female experimenters for five minutes a day for 10 days before any experimental manipulations were done to ensure the rats were used to the experimenters.

“We watched a lot of different variables and compared how the animals responded to a male and a female experimenter working with them,” says Metz. “We saw that the presence of a human makes a huge difference and we saw again that the rats responded to the T-shirt. It’s not only visual interaction the rats responded to, but also some olfactory cues that influenced their behaviour.”

Researchers measured the rats’ stress levels before and after they were subjected to a mildly stressful situation. Infrared thermography was used to detect skin temperature and blood samples were taken to determine the levels of hormones involved in the stress response (corticosterone and oxytocin). Female rats in the presence of a male experimenter or T-shirt worn by a male experimenter showed higher levels of corticosterone and lower levels of oxytocin, the so-called bonding hormone. They also responded to the presence of a male experimenter by displaying more anxiety-like behaviour, such as spending more time near the walls of their enclosure, and had higher body surface temperatures.

“An interesting finding is that female rats display these heightened stress responses even after frequent exposure to male experimenters,” says Faraji. “We call it the male observer effect.”

“It’s really a very important finding because it will affect how we design experiments,” says Metz. “I don’t mean we should only have female experimenters work with rats or any laboratory animals, but we need to report it and have better standards of how we pursue research with laboratory animals. We also need to be aware that our presence and our handling affects them.”

The findings may help explain the replication crisis, which occurs when the same experiments done at different labs produce different results. When a study’s results can’t be replicated from one lab to another, the credibility of the findings can be in doubt.

“All scientists are concerned about controlling unwanted factors when they are manipulating experimental variables,” says Faraji. “These results address this concern and reveal one of these factors in the field.”

Given the study results, Metz says it would be better to have a series of observations or tests and then take an average or, as Faraji suggests might be possible in the future, to eliminate the variable by using robotics. The ultimate goal is to ensure results obtained in the preclinical stages are reliable and will lead to successful clinical trials in humans. Rodents are often used in preclinical studies, which take place before any testing in humans is done, to determine if a drug, treatment or procedure might be useful.

“Because experimenter sex in animal studies is not commonly reported, improved standards should require researchers to report the sex of experimenters,” says Metz. “We cannot avoid the presence of a human experimenter or handling the animals in many situations, but we need to be aware of these variables and maybe include appropriate control situations in an experiment to be sure about the results.”

Perhaps the study results aren’t surprising to pet owners, who can attest to the bonds they have with their pets. One study, referred to in an article in Smithsonian Magazine, explored the bond between humans and their dog companions and found that dogs and humans gazing into each other’s eyes caused both to secrete oxytocin.

U of L doctoral student wins prestigious Brain Star Award

caroline.zentner — Thu, 24 May 2018 21:51:48 +0000

For her work in illuminating the multigenerational effects of prenatal stress, Mirela Ambeskovic has been awarded a Canadian Institutes of Health Research (CIHR) Brain Star award, one of 15 winners of the $1,500-award across the country.

“It was a pleasant surprise, for sure,” says Ambeskovic. “I’m honoured to have received this award and grateful for this funding and all the funding I’ve had during my studies. It has made it easier to focus on research and my studies.”

Ambeskovic (BSc ’09, BA ’11, MSc ’13), a PhD candidate in neuroscience who works in Dr. Gerlinde Metz’s lab, looked at the effects of prenatal stress on motor development in male and female rats. In the study, which was published last year in Cerebral Cortex, she compared the behaviours of animals that had experienced one generation of stress with those that had experienced four generations of stress.

“We found that multigenerational stress altered behaviour and brain lateralization in males, while improving behavioural abilities in females,” she says.

While the animals were performing a reaching task, she found that multigenerational stress shifted paw performance to favour left-handedness in males, while it had no effects on paw preference in females, showing that ancestral stress may have a protective effect for females.

“It could be that, through epigenetic mechanisms, our moms prepare us for a stressful environment that might be coming down the road, where females are programmed to cope with stressful environments more sufficiently as they will be the bearers of the future generation,” says Ambeskovic.

In the same way, males affected by ancestral stress might be better prepared to defend their territory because they are more adaptable, perhaps because they could be more prone to using both paws if needed.

“Mirela’s findings illustrate the complex consequences of stress on development,” says Metz. “Stress is primarily supposed to promote survival and to make sure that behaviour adapts to a changing environment. The brain readily responds to stress and changes its structure accordingly.”

The Brain Star Award, through the Institute Community Support Grants and Awards program of CIHR, recognizes the excellence of research done in Canada by students and trainees.

Researchers show prenatal stress influences new behavioural traits, including handedness

caroline.zentner — Tue, 26 Apr 2016 17:41:22 +0000

A new study by researchers at the Canadian Centre for Behavioural Neuroscience at the ��Ѹ��Դ��߿�Ƭ of Lethbridge, recently published in Cerebral Cortex, shows the effects of prenatal stress accumulate across generations and can affect behavioural traits, such as right- and left-handedness.

Mirela Ambeskovic, a PhD candidate working in the laboratory of Dr. Gerlinde Metz, was the lead author in a study that examined the effects of prenatal stress over four generations of rats.

Mirela Ambeskovic

“Our original idea was just to test the effects of prenatal stress on motor development to see if it affects males and females differently and whether one generation of stress would have a different effect than four generations of stress,” says Ambeskovic. “But while I was testing my animals’ fine motor skills in a reaching task, I noticed something interesting.”

Ambeskovic found that males who were in the multigenerational stress group were predominantly left-pawed, while females in the same group were both left- and right-pawed. In comparison, males whose ancestors were only exposed to stress once, either in their mothers or their great-great-grandmothers, did not show a significant increase in being left-pawed.

She and Metz, a neuroscience professor, went through previous research and found no conclusive evidence of a genetic link to handedness.

“We thought maybe it’s an epigenetic effect because these animals have been stressed and epigenetically programmed across generations,” says Ambeskovic. “We did see a difference in behaviour so the stress had negative effects on fine motor skills in males and it actually had positive effects in females. Our females were better at the reaching task than the control group which had experienced no stress.”

With the help of Dr. Bryan Kolb, also a neuroscience professor, they examined the neural structure of the brains of these male rats. The researchers found their right hemispheres — which are linked to the left paw — showed increased complexity and spine density, or more connections, in their neurons.

Dr. Gerlinde Metz

“Ancestral stress often affects males more than females,” says Ambeskovic. “It affects their behaviour and it also changes their brain organization, so we see the structural changes in the neurons and their spine density.”

Researchers don’t know what comes first, paw preference or a dominant right brain hemisphere but even so, such changes should be adaptive. Ambeskovic says ancestral stress may have a protective effect for females.

“It could be that, through epigenetics, our moms prepare us for a stressful environment that might be coming down the road and it’s more important for females to know how to cope with it as they will be the bearers of the future generation,” says Ambeskovic.

“There have been studies, that for programming across generations, there’s an increase in behavioural flexibility, especially in the males. That’s what we’re seeing here. There’s more flexibility to do more tasks,” says Metz.

Ambeskovic is also looking at the effects of multigenerational stress and aging. She has found that males exposed to multigenerational stress are more susceptible to chronic diseases as they age. This study, and others, show the brain can be changed by experience and this could help pave the way to developing interventions that could change the brain in beneficial ways earlier in life.

Doctoral student using Parkland Institute award for study to uncover links between prenatal stress and aging

trevor.kenney — Wed, 17 Dec 2014 22:35:32 +0000

The effects of prenatal stress can be seen across generations and Mirela Ambeskovic is studying those effects across a lifespan.

Ambeskovic (BA '12, MSc '14), a ��Ѹ��Դ��߿�Ƭ of Lethbridge doctoral student studying under neuroscientist Dr. Gerlinde Metz, became interested in studying the effects of prenatal stress because of the influence it had on her and her family when they lived in Bosnia. Ambeskovic’s grandmother experienced prenatal stress in the aftermath of the Second World War, when shelter and food were scarce, as did her mother a generation later.

Mirela Ambeskovic is seeking to determine how prenatal stress programs the brain and behaviour across generations.

“I was a prenatally stressed baby, too. When my mom was pregnant with me, my dad went into the army. So she was home alone and had to deal with lots,” says Ambeskovic. “In a way, I feel like it maybe benefited me, building the same kind of resilience I see in the subjects we test.”

She came to Canada in 1998 after her family, including her mother and two siblings, was displaced in the Bosnian war that lasted from 1992 to 1995. She attended Winston Churchill High School and started studying biology and psychology at the ��Ѹ��Դ��߿�Ƭ of Lethbridge a year after graduating. Two years later, she made the switch to neuroscience and got some experience working in the laboratory under Dr. Deborah Saucier, a former U of L professor of neuroscience. After she took a class on stress with Dr. Metz, she knew she’d found the field she wanted to explore further. Ambeskovic asked if Metz would take her on as a master’s student and a few days later she was in the lab.

“Everything fell into place. I stuck with it and now I’m doing my PhD. I love coming to work every day,” says Ambeskovic.

Her own stress level recently received a little reprieve when she was awarded a $5,000 scholarship through the Parkland Institute. With the financial pressure alleviated, she’ll be able to focus solely on her research.

“The main goal of my research is to determine how prenatal stress programs the brain and behaviour across generations,” she says. “I am interested in possible prenatal stress and aging interactions. I assess for cognitive and motor functions, depression and anxiety levels and brain plasticity in rats from young adulthood to middle-aged and aged.”

She studies rats over an 18-month period, equivalent to a human lifespan of 60 to 70 years. Every six months she evaluates brain and behavioural changes in the animals. Ambeskovic looks specifically at the prefrontal cortex, the area of the brain that integrates learning, memory and emotion and helps in decision-making. She also compares the effects of prenatal stress on males and females to see if any sex differences exist and whether the rats’ lifespans and susceptibility to diseases like Alzheimer’s, Parkinson’s, diabetes, kidney failure and heart failure, are affected.

In addition to a control group of non-stressed rats, Ambeskovic studies a group of rats where only the great-grandmother was prenatally stressed and not subsequent generations, and another group where all four generations experienced prenatal stress. While her research isn’t yet completed, she’s already found some results that point to the effects of prenatal stress.

“Prenatally stressed animals have a shorter lifespan and are more prone to diseases earlier in life than non-stressed individuals,” she says. “Prenatally stressed animals age faster with earlier onset of motor and cognitive deficits. Interestingly, the males are more affected than females. Females deal much better with prenatal stress than males do. Their behaviour is not as affected, nor is their brain. It actually appears that the prenatally stressed females build resilience to stress and show enhanced cognitive and motor functions.”

Not all prenatal stress is bad. Some stress is good as it prepares individuals for the environment they are born into. For instance, an animal pre-programmed to survive in a stressful environment will cope better and go on to reproduce, ensuring survival of the species, and this may have evolutionary purposes.

“It catches up to them as they get older. The organism kind of gets run down,” says Ambeskovic. “Maybe that’s why we see the difference between males and females. Males are OK when they are younger to the stage that reproduction can happen. As they get older, their bodies run down and they start giving up faster. They age faster than the females. But why females are so resilient all the time I’m not quite sure.”

In a separate study, Ambeskovic looked at the effects of prenatal stress on the emotional or mental states in young and middle-aged male rats. She found increased levels of depression and anxiety, enhanced hyperactivity and stress hormone levels in middle-aged rats. She called this cluster of behaviours exhibited by her male rats a ‘middle-age crisis’ as it resonated with similar behaviours in humans.

Ambeskovic is also looking at the epigenetic effects of prenatal stress. Certain genes, or parts of genes, may be turned on or off, depending on the environment and the rat’s experiences. For example, putting animals in an enriched environment has been shown to reverse some of the effects of prenatal stress.

“In our multi-generationally stressed animals, a lot of genes seem to be either up or down regulated and these seem to be involved in aging and immune functions, along with diabetes and depression. We need to look further into specific genes and micro-RNAs (small sequences of specific DNA) that might be changing,” she says of future studies.

UNews - Mirela Ambeskovic

Male experimenters make female rats uneasy

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