Differential Effects of Controllable Stress Exposure on Subsequent Extinction Learning in Adult Rats

Adolescent stress avoidance influences cue-induced heroin seeking and chaperonin gene expression in the dorsal striatum of adult female rats

Background: Females remain underrepresented in opioid use disorder (OUD) research, particularly regarding dorsal striatal neuroadaptations. Chaperonins seem to play a role in opioid-induced neural plasticity, yet their contribution to OUD-related changes in the dorsal striatum (DS) remains poorly understood. Given known sex differences in opioid sensitivity, it is important to determine how chaperonin expression contributes to OUD-related adaptations in females.Objective: To investigate how stressor controllability during adolescence influences heroin self-administration (SA) and responses to drug-paired cues in adult female rats, focusing on differential gene expression of chaperonins in the DS.Methods: Female rats were exposed to stress avoidance training during adolescence. These rats underwent, in adulthood, heroin SA followed by cue-induced seeking tests after early and prolonged abstinence.Results: Heroin intake during SA was similar between stress-avoiding and stress-naïve females (n = 8/group, p = .89). However, stress-avoiding females exhibited reduced drug-seeking behavior in response to drug cues at 14 days of abstinence compared to controls (p < .05; d = 0.99), suggesting a protective effect of stressor controllability. qPCR showed that the gene expression of Hspa5, a heat shock protein, was elevated in the dorsolateral striatum (DLS) of stress-avoiding females (p < .05; Cohen d > 1.0). Hspb1 gene expression was upregulated in the dorsomedial striatum (DMS) of stress-avoiding females (p < .05; d > 1.0).Conclusion: These findings suggest that chaperonin dysregulation links opioid exposure and stress avoidance conditions. Increased Hspa5 in the DLS and Hspb1 in the DMS may contribute to the observed behavioral differences supporting further preclinical investigation with clinical implications for stress and OUD.

Reducing glutamic acid decarboxylase in the dorsal dentate gyrus attenuates juvenile stress induced emotional and cognitive deficits

A high degree of regional, temporal and molecular specificity is evident in the regulation of GABAergic signaling in stress-responsive circuitry, hampering the use of systemic GABAergic modulators for the treatment of stress-related psychopathology. Here we investigated the effectiveness of local intervention with the GABA synthetic enzymes GAD65 and GAD67 in the dorsal dentate gyrus (dDG) vs ventral DG (vDG) to alleviate anxiety-like behavior and stress-induced symptoms in the rat. We induced shRNA-mediated knock down of either GAD65 or GAD67 with lentiviral vectors microinjected into the dDG or vDG of young adult male rats and examined anxiety behavior, learning and memory performance. Subsequently we tested whether reducing GAD65 expression in the dDG would also confer resilience against juvenile stress-induced behavioral and physiological symptoms in adulthood. While knock down of either isoform in the vDG increased anxiety levels in the open field and the elevated plus maze tests, the knock down of GAD65, but not GAD67, in the dDG conferred a significant reduction in anxiety levels. Strikingly, this manipulation also attenuated juvenile stress evoked anxiety behavior, cognitive and synaptic plasticity impairments. Local GABAergic circuitry in the DG plays an important and highly region-specific role in control of emotional behavior and stress responding. Reduction of GAD65 expression in the dDG appears to provide resilience to juvenile stress-induced emotional and cognitive deficits, opening a new direction towards addressing a significant risk factor for developing stress and trauma-related psychopathologies later in life.

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GAD67/65 in the dorsal/ventral dentate gyrus differentially modulate anxiety.

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Reduced GAD65 expression in the dorsal dentate gyrus supports stress resilience.

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The dorsal dentate gyrus plays a key role in stress resilience.