assessing-changes-synaptic-plasticity-using-an-awake-closed-head

Assessing Changes in Synaptic Plasticity Using an Awake Closed-Head Injury Model of Mild Traumatic Brain Injury

Mild traumatic brain injuries (mTBIs) are a prevalent health issue in North America. There is increasing pressure to utilize ecologically valid models of ...

University of Victoria

Marijuana and alcohol are both substances that, when used during pregnancy, may have profound effects on the developing fetus. There is evidence to suggest that both drugs have the capacity to affect working memory, one function of the hippocampal formation; however, there is a paucity of data on how perinatal exposure to alcohol or cannabis impacts the process of adult neurogenesis.

A Systematic Review of the Effects of Perinatal Alcohol Exposure and Perinatal Marijuana Exposure on Adult Neurogenesis in the Dentate Gyrus.

Mild traumatic brain injury (mTBI) is a putative risk factor for dementia; however, despite having apparent face validity, the evidence supporting this hypothesis remains inconclusive. Understanding the role of mTBI as a risk factor is becoming increasingly important given the high prevalence of mTBI, and the increasing societal burden of dementia.

Does Mild Traumatic Brain Injury Increase the Risk for Dementia? A Systematic Review and Meta-Analysis.

 It is becoming increasingly recognized that there is significant interneuron degeneration in Alzheimer's disease. As the hippocampus is integral for learning and memory, we performed a systematic review of primary literature focused on the relationship between Alzheimer's and hippocampal interneurons. In this study, we summarize the experimental work performed to date and identify opportunities for future experiments.  This PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses)-style systematic review seeks to summarize the findings of all accessible research focused on cholecystokinin (CCK), neuropeptide Y (NPY), parvalbumin (PV), and somatostatin (SOM) interneurons in the hippocampal formation.  One thousand five hundred ninety-three articles were pulled from PubMed, PsycInfo, and Web of Science, based on three blocks of search terms. There were 45 articles that met all the predetermined inclusion/exclusion criteria. There is strong evidence that PV interneurons are affected early in the disease by toxic amyloid beta (Aβ) fragments; SOM interneurons are affected indirectly while the SOM neuropeptide may act to slowly worsen toxic Aβ fragment accumulation, whereas NPY- and CCK-positive interneurons are affected later in the progression of the disease.  Fewer studies have been performed on NPY and CCK interneurons, and there is room for further investigations regarding the role of PV interneurons in Alzheimer's to help resolve contradictory findings. This review found that PV interneurons are affected early in the disease, but only in Alzheimer's precursor protein but not tau models. NPY and CCK interneurons were found to be affected later in the disease, and SOM interneurons vary greatly. Future studies may consider reporting immunohistochemical studies inclusive of either cell location or morphology-as well as marker to give a more robust picture of the disease.

Understanding Changes in Hippocampal Interneurons Subtypes in the Pathogenesis of Alzheimer's Disease: A Systematic Review.

We examined how acute ethanol (EtOH) exposure affects long term depression (LTD) in the dentate gyrus (DG) of the hippocampus in juvenile rats. EtOH is thought to directly modulate n-methyl-D-aspartate receptor (NMDAr) currents, which are believed important for LTD induction. LTD in turn is believed to play an important developmental role in the hippocampus by facilitating synaptic pruning.

Effects of Ethanol on Synaptic Plasticity and NMDA Currents in the Juvenile Rat Dentate Gyrus.

We recently showed that alcohol and cannabis can interact prenatally, and in a recent review paper, we identified parvalbumin-positive (PV) interneurons in the hippocampus as a potential point of convergence for these teratogens.

Article	Year
A Systematic Review of the Effects of Perinatal Alcohol Exposure and Perinatal Marijuana Exposure on Adult Neurogenesis in the Dentate Gyrus. Alcoholism, clinical and experimental research\| PubMed ID: 32246781	2020
Does Mild Traumatic Brain Injury Increase the Risk for Dementia? A Systematic Review and Meta-Analysis. Journal of Alzheimer's disease : JAD\| PubMed ID: 33044182	2020
Understanding Changes in Hippocampal Interneurons Subtypes in the Pathogenesis of Alzheimer's Disease: A Systematic Review. Brain connectivity\| PubMed ID: 33559520	2021
Effects of Ethanol on Synaptic Plasticity and NMDA Currents in the Juvenile Rat Dentate Gyrus. Brain plasticity (Amsterdam, Netherlands)\| PubMed ID: 33680851	2020
Prenatal alcohol and cannabis exposure can have opposing and region-specific effects on parvalbumin interneuron numbers in the hippocampus. Alcoholism, clinical and experimental research\| PubMed ID: 34523142	2021

Hannah M. O. Reid

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