Biology subjects

Mahbod, P.

Publications and source records attributed to Mahbod, P..

4 recordsLinked to original sources

bioRxiv2026

Adolescent Stress Exposure: Behavioral Consequences and Molecular Mechanisms in Corticolimbic Networks

IntroductionAdolescence is a sensitive developmental period during which chronic stress can induce lasting adaptations in corticolimbic circuits involved in stress regulation, cognition, and emotional behavior. We examined the long-term behavioral, endocrine, and molecular consequences of adolescent chronic variable stress (CVS) in male and female rats, focusing on the infralimbic cortex (IL) and basolateral amygdala (BLA) MethodsSprague Dawley rats of both sexes were exposed to CVS during late adolescence and evaluated in adulthood after an extensive recovery period. Behavioral testing included cued fear conditioning and extinction recall, delayed spatial win-shift, novel object recognition, Morris water maze, three-chamber social behavior, and passive avoidance. HPA-axis reactivity to acute restraint was assessed. Targeted qPCR was used to measure stress-related gene expression in the IL and BLA immediately after stress or after a 5-week recovery period ResultsAdolescent CVS did not cause generalized cognitive impairment, but instead produced selective, sex-specific effects. Females had reduced HPA responses to acute stress and mild deficits in delayed spatial win-shift performance, together with long-term IL changes in genes related to adrenergic signaling, plasticity, and GABA clearance. Males showed enhanced Morris water maze probe retention, weaker novel object discrimination, altered passive avoidance with marked inter-individual variability, and enhanced social preference. At the molecular level, males exhibited long-term upregulation of Fkbp5 in IL and downregulation of PACAP, 1D adrenergic receptor, and proenkephalin in BLA, whereas females showed delayed PACAP upregulation in BLA DiscussionAdolescent CVS induces persistent, sex- and region-specific recalibration of corticolimbic function, supporting distinct patterns of vulnerability and resilience, rather than uniform stress pathology.

animal behavior and cognition↗

bioRxiv2021

Glucoregulation and coping behavior after chronic stress: sex differences across the lifespan

Exposure to prolonged stress during adolescence taxes adaptive and homeostatic processes leading to deleterious behavioral and metabolic outcomes. Although previous pre-clinical studies found effects of early life stress on cognition and stress hormone reactivity, these studies largely focused on males. The purpose of the current study was to determine how biological sex shapes behavioral coping and metabolic health across the lifespan after chronic stress. We hypothesized that examining chronic stress-induced behavioral and endocrine outcomes would reveal sex differences in the biological basis of susceptibility. During the late adolescent period, male and female Sprague-Dawley rats experienced chronic variable stress (CVS). Following completion of CVS, all rats experienced a forced swim test (FST) followed 3 days later by a fasted glucose tolerance test (GTT). The FST was used to determine coping in response to a stressor. Endocrine metabolic function was evaluated in the GTT by measuring glucose and corticosterone, the primary rodent glucocorticoid. Animals then aged to 15 months when the FST and GTT were repeated. In young animals, chronically stressed females exhibited more passive coping and corticosterone release in the FST. Additionally, chronically stressed females had elevated corticosterone and impaired glucose clearance in the GTT. Aging affected all measurements as behavioral and endocrine outcomes were sex specific. Furthermore, regression analysis between hormonal and behavioral responses identified associations depending on sex and stress. Collectively, these data indicate female susceptibility to the effects of chronic stress during adolescence. Further, translational investigation of coping style and glucose homeostasis may identify biomarkers for stress-related disorders.

animal behavior and cognition↗

bioRxiv2019

Chemogenetic Inhibition of Infralimbic Prefrontal Cortex GABA-ergic Parvalbuminpositive Interneurons Attenuates Chronic Stress Adaptions in Male Mice

Hypofunction of the prefrontal cortex (PFC) contributes to stress-related neuropsychiatric illnesses. Mechanisms leading to prefrontal hypoactivity remain to be determined. Prior evidence suggests that enhanced activity of parvalbumin (PV) expressing GABAergic interneurons (INs) play a role in chronic stress related pathologies. In this study, the role of PFC PV INs in stress related phenotypes were explored using Cre inducible inhibitory DREADDs (Designer Receptors Exclusively Activated by Designer Drugs). Mice were first tested in the tail suspension test (TST) to determine the effects of PV IN inhibition during acute stress. Following this, the long term impact of PV IN inhibition during chronic variable stress (CVS) was tested in the forced swim test (FST). Acute PV IN inhibition reduced active (struggling) and increased passive coping behaviors (immobility) in the TST. In contrast, inhibition of PV INs during CVS increased active and reduced passive coping behaviors in the FST. Moreover, chronic inhibition of PV INs attenuated CVS-induced changes in Fos expression in the prelimbic cortex, basolateral amygdala and ventrolateral periaqueductal gray and also prevented adrenal hypertrophy and body weight loss associated with chronic stress. Our results suggest differential roles of PV INs to acute vs chronic stress, indicative of distinct biological mechanisms underlying acute vs. chronic stress responses. Our results also indicate a role for PV INs in driving chronic stress adaptation and support literature evidence suggesting cortical GABAergic interneurons as a therapeutic target in stress related diseases.\n\nSIGNIFICANCEStress related diseases are associated with prefrontal hypoactivity, the mechanism of which is currently not known. In this study we showed that by inhibiting prefrontal GABA-ergic Parvalbumin interneurons (PV INs) using DREADDs, we can attenuate some of chronic stress related phenotypes. Additionally, we showed that modulation of PV IN activity during acute vs chronic stress had opposing effects on stress coping strategies, suggesting different underlying mechanisms behind acute vs chronic stress paradigms. Our findings indicate that GABA-ergic PV INs may be involved in driving stress related phenotypes and thereby an important target for treatment of stress-related illnesses. Our data suggest that reducing PV IN activity to promote prefrontal output may be an effective treatment strategy for stress related disorders.

neuroscience↗

bioRxiv2019

Use of CRISPR/Cas9 Gene Targeting to Conditionally Delete Glucocorticoid Receptors in Rat Brain

Glucocorticoid receptors (GR) have diverse functions relevant to maintenance of homeostasis and adaptation to environmental challenges. Understanding the importance of tissue-specific GR function in physiology and behavior has been hampered by near-ubiquitous localization in brain and body. Here we use CRISPR/Cas9 gene editing to create a conditional GR knockout in Sprague Dawley rats. To test the impact of cell-and region-specific GR deletion on physiology and behavior, we targeted GR knockout to output neurons of the prelimbic cortex. Prelimbic deletion of GR in females caused deficits in acquisition and extinction of fear memory during auditory fear conditioning, whereas males exhibit enhanced active-coping behavior during forced swim. Our data support the utility of this conditional knockout rat to afford high-precision deletion of GR across a variety of contexts, ranging from neuronal depletion to circuit-wide manipulations, leveraging the behavioral tractability and enhanced brain size of the rat as a model organism.

neuroscience↗