Date of Award

2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Program

Biomedical Science

Track

Neuroscience

Research Advisor

Dean Kirson

Committee

Anna Bukiya; Brendan Tunstall; Nicole Ashpole

Keywords

Alcohol use disorder, Central Amygdala, Corticotrophin-releasing factor, Electrophysiology, Oxytocin, Serotonin

Abstract

Alcohol use disorder (AUD) is a chronic and relapsing condition characterized by compulsive alcohol seeking and consumption, loss of control over intake, and the emergence of negative affective states during withdrawal. The central amygdala (CeA), a predominantly GABAergic structure that integrates stress and reward signals, plays a critical role in the emotional and motivational processes that sustain alcohol dependence. Although pharmacotherapies targeting stress-related neuropeptide systems have shown promise, their efficacy remains limited. Neurotransmitter systems such as oxytocin (OXT), corticotropin-releasing factor (CRF), and serotonin (5-HT) have demonstrated therapeutic potential in reducing alcohol-related behaviors. However, how these neuromodulators alter GABAergic transmission in the CeA and interact with alcohol, particularly at the circuit level, remains poorly understood. This dissertation investigated how OXT, CRF, and 5-HT modulate GABAergic inhibitory transmission in the CeA under alcohol-naïve and chronic alcohol–dependent conditions in male and female Wistar rats. Using whole-cell patch-clamp electrophysiology in acute brain slices, inhibitory postsynaptic currents (IPSCs) were recorded to assess presynaptic and postsynaptic mechanisms of neuromodulation. Immunocytochemistry was used to quantify hypothalamic OXT-expressing neurons, and in situ hybridization was used to measure mRNA expression levels of oxytocin receptor (OXTR), CRF, and serotonin receptors (5-HT1A, 5-HT1B, and 5-HT2C) within the CeA. Electrophysiological findings revealed distinct sex-dependent and subregion-specific mechanisms of modulation. In males, both naïve and dependent, acute alcohol increased GABAergic transmission in the medial CeA (CeM) and lateral CeA (CeL). OXT suppressed presynaptic GABA release in the CeL of naïve males and blocked alcohol-induced facilitation of GABA transmission in both CeL and CeM of naïve and dependent males. In contrast, in females, OXT increased GABAergic tone in the CeM, and co-application of alcohol further potentiated this effect. Exogenous CRF produced modest postsynaptic effects selectively in alcohol-dependent males within the CeL, whereas CRF1 receptor antagonism decreased presynaptic GABA release in naïve males and blocked alcohol-induced facilitation regardless of alcohol history. Serotonin increased presynaptic GABA release in females (independent of alcohol history) and in naïve males within the CeL. Pharmacological activation or inhibition of serotonergic receptors, along with chemogenetic suppression of 5-HT signaling, attenuated or prevented alcohol-induced increases in GABA transmission in males. Neurohistochemical analysis revealed that chronic alcohol exposure reduced hypothalamic OXT neuron numbers, while RNAscope analyses demonstrated that chronic alcohol altered OXTR and CRF receptor expression in the CeA. Females expressed higher levels of OXTR and CRF mRNA regardless of alcohol history, whereas males, especially dependent males, exhibited greater expression of serotonin receptor subtypes. Together, these findings demonstrate that alcohol, OXT, CRF, and 5-HT interact to shape CeA inhibitory microcircuits through sex- and subregion-specific mechanisms. By elucidating how these neuromodulatory systems regulate inhibitory tone within the CeM and CeL, this dissertation identifies neurobiological substrates that may inform the development of targeted, sex-specific pharmacotherapies for alcohol use disorder.

ORCID

0009-0000-3600-2313

DOI

10.21007/etd.cghs.2025.0706

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