Social isolation is stressful. Scientists have known it for decades. They also know that isolation causes changes to occur in the brains of rodents and primates. But most studies examine the effects of isolation during childhood; and the ones that do focus on adulthood tend to use male subjects. For the first time, researchers in Spain show that long-term social isolation causes part of the brain to shrink in the adult female degu, a highly social rat-like animal native to South America.
Foods like tuna fish and Brazil nuts are rich in selenium, a mineral that scientists say has antioxidant effects, keeping the brain healthy and free of clutter so cells can work smoothly together. A key element of this process is Selenoprotein P (Sepp1) – a protein that delivers selenium to neurons by binding with another protein – ApoER2. Neuroscientists at the University of Hawaii say Sepp1 plays a critical role in brain function, and deficits may play a part in mental illnesses like schizophrenia.
In their study published in Neuroscience, the researchers investigate the relationship between Sepp1 and parvalbumin (PV)-interneurons – a class of brain cell that controls firing rates and synchronizes spiking activity among other groups of neurons. Previous research shows that these cells need selenium to develop properly, so the scientists set out to find out what affect a Sepp1 deficit would have on the mouse brain.
Led by Dr. Matthew W. Pitts, the research team compared the brains of wild type mice with Sepp1 deficient mice. They used a Zeiss Axioskop microscope equipped with Stereo Investigator to conduct a stereological analysis of PV-interneurons in several different regions of the mouse brain. Using Stereo Investigator’s optical fractionator probe, they observed reduced numbers of PV-interneurons along with elevated oxidative stress in the inferior colliculus of Sepp1 deficient mice, a region involved in processing auditory information.
“Stereo Investigator was particularly useful for estimating cell density in larger brain structures, such as the inferior colliculus,” said Dr. Pitts.
Since scientists speculate that dysfunctional PV-interneuron networks may be involved in neuropsychiatric conditions, the researchers conducted behavioral tests that showed impairments in contextual fear extinction, latent inhibition, and sensorimotor gating in the Sepp1 deficient mice – behaviors observed in some mental illnesses.
“Previous studies (Valentine et al., 2008) and our findings together indicate that ApoER2- mediated uptake of Sepp1 serves an important neuroprotective role in the inferior colliculus,” the authors say in their paper. “These findings may have relevance to neuropsychiatric conditions in which dysfunc- tional PV-interneuron networks have been implicated, such as epilepsy and schizophrenia.”
Pitts M.W., Raman A.V., Hashimoto A.C., Todorovic C., Nichols R.A., Berry M.J. Deletion of selenoprotein P results in impaired function of parvalbumin interneurons and alterations in fear learning and sensorimotor gating. Neuroscience. 2012 Apr 19;208:58-68. doi: 10.1016/j.neuroscience.2012.02.017.
Each year, nearly ninety thousand children are born extremely premature in the United States – that is, before 28 weeks gestation. Most of them survive, but about half the survivors suffer from severe health problems throughout their childhood and into adulthood, including learning and behavioral disorders such as ADHD.
“Treatment options are clearly urgently required to prevent the brain damage and associated memory deficits that follow extremely premature birth,” say the authors of a study published last month in the Journal of Neuroscience.
Treatment options are limited, the authors say, because current small animal models fall short in their mimicry of the extremely premature human brain. However, the researchers from the University of Otago in New Zealand have come up with a new animal model for human extreme prematurity, which they say more closely resembles the pathological and behavioral deficits seen among this population.
When it comes to health, kidneys are critical. From regulating blood composition to maintaining calcium levels, the pair of bean-shaped organs perform several essential tasks. Needless to say, interruption to kidney function can be disastrous.
Working with scientists in South Korea, researchers at the University of Virginia found a surprisingly simple treatment for renal ischemia-reperfusion injury (IRI) in mice, which is a model of acute kidney injury (AKI) in humans.
The researchers found that mice exposed to ultrasound prior to IRI “had preserved kidney structure and function accompanied by a reduction in tissue inflammation,” they report in their paper published this month in the Journal of the American Society of Nephrology.
Life’s little pleasures often elude those suffering from depression, including rats, who show little interest in sugar water after experiencing stress. This behavior leads scientists to speculate that the illness might be characterized by a defect in the brain’s neural reward circuit.
Recent research focuses on a key element of this circuit – the nucleus accumbens (NAc), part of the brain region known as the ventral striatum, which is thought to regulate motivation and reward processing. In a new study of stress-induced depression in rats, researchers at the University of Minho in Braga, Portugal saw morphological changes in the dendrites of medium spiny neurons in the NAc, alongside disturbances in gene expression in this region. They also saw these changes reversed after administering antidepressants.
By using Neurolucida Explorer to analyze 3D reconstructions of medium spiny neurons generated with Neurolucida, the researchers observed longer than normal dendrites and greater spine density in the depressed rats. According to the paper, these findings contrast with studies of the hippocampus and prefrontal cortex, where chronic stress leads to shorter dendrites.
A Stereo Investigator system for confocal stereology was installed in Dr. Michelle Monje’s lab in the Department of Neurology and Neurological Sciences at Stanford University School of Medicine. Dr. Monje and her lab members will use the system to investigate the molecular and cellular mechanisms of postnatal neurodevelopment.
Dr. Julie Korich, staff scientist at MBF, installed Stereo Investigator on a Zeiss laser scanning confocal microscope and trained the lab members on how to use the system.
During the training, Dr. Korich discussed how Stereo Investigator integrates with Zeiss’ microscope software, explained the Cavalieri probe for estimating regional volume, and showed the lab how to use Stereo Investigator to collect confocal image stacks in the systematic and random way that’s necessary for unbiased stereology. She also explained how to count cells from those image stacks and from 3D virtual slides with Stereo Investigator on a computer away from the microscope.
Click here to learn more about how researchers are using Stereo Investigator in their labs.
The placenta delivers nutrients from a mother’s blood to a developing fetus. It also produces hormones that help the baby grow during its forty or so weeks in utero. But the placenta’s powerhouse abilities don’t end there. The organ provides a wealth of information about the infant’s future health, allowing doctors to make predictions about whether or not the child will develop autism or, later in life, heart disease.
If one area isn’t working, another part can step in. Plasticity is one of the brain’s most beautiful attributes. Recent research has documented the organ’s ability to compensate in the face of damage, and now a new study identifies a key region for compensation when the damage occurs in the hippocampus.
The region is the medial prefrontal cortex (mPFC). It’s an integral part of the hippocampal-prefrontal-amygdala circuit involved with memory formation – specifically with contextual fear memories. In their study, published last month in Proceedings of the National Academy of Sciences, researchers at the University of California, Los Angeles identify a microcircuit in the mPFC that can encode memories when the dorsal hippocampus is damaged.
Obstetricians and midwifes have long hailed the benefits of folic acid during pregnancy. Now new research offers evidence that choline is another important nutrient for the developing fetus. Found in foods like eggs and cauliflower, choline is known to aid healthy liver function. But in the past few years, studies have shown that the nutrient also plays a role in brain development. One recent study by Velasquez and colleagues claims that increased choline during pregnancy may offer a possible therapy for Down syndrome.
According to scientists at the Hotchkiss Brain Institute in Calgary, Canada, there is evidence for increased neurogenesis in adult mice reared by two parents. Their study also describes other interesting findings, such as the fact that increased neurogenesis persists in the next generation, or that the effects of differences in rearing affect males and females differently.