During abstinence in alcoholics, stress induces a dysfunctional HPA axis response, an increased fMRI response accompanied by negative affect, and excess drinking upon relapse. In spite of these well documented events induced by stress in alcoholics, the neural basis of these facilitated dysfunctional responses is unknown. In this respect, even though corticotropin releasing factor (CRF) is accepted to contribute to stress induced dysfunctions after chronic alcohol (CA), an overlooked area is the possibility that the stress increase in cytokines also contributes to neuromediation of these effects of stress during abstinence. The goal of the present research is to provide support for the hypothesis that CA induces a persisting neural maladaptation that supports the stress induction of cytokines in selected brain regions associated with dysfunctional responses, facilitates stress and cytokine-induced alcohol drinking in models of relapse, alters factors that can affect stress-induced expression of brain cytokines, and intensifies cytokine responses from neurons in the central amygdala (CeA)—a brain site that supports stress-induced negative affect. The innovative strategies to be undertaken will allow testing this hypothesis. Studies will first assess if adolescent and adult rats with differing CA exposures induce a common increase in the regional distribution cytokines in brain, but differing durations of the stress-induced increase in cytokines after CA. Subsequently, to test further that cytokines have a role in stress, determinations will define whether cytokines will substitute for stress facilitation of the alcohol deprivation effect (ADE) and enhancement of operant responding for alcohol. To explore possible means by which the degree of brain cytokines is increased by stress alone or after CA, investigations will determine if the alteration in the cytokine increase during stress alone and/or after CA exposure relates to CRF activity, to an indirect involvement of an endogenous agonist on TLR4 receptors, or to induction of HPA axis dysfunction. To explore neural actions of cytokines released by stress after CA, changes in neural excitability, pre-synaptic release of GABA and/or glutamate, as well as post-synaptic changes of CeA neurons by cytokines will be explored in controls and after CA exposure. A particularly innovative component is characterization of cell-types sensitive to actions of cytokines in the lateral or medial portions of the CeA with either oxytocin or vasopressin, respectively, and exploration of whether neural actions of cytokines on CeA neurons depend upon CRF. With these important processes to resolve issues concerning cytokine neuromediation in brain, a rational basis is expected to emerge that cytokine action initiated by stress after CA exposure contributes to the negative consequences associated with stress in the abstinent alcoholic. This innovative effort should be critical for redirecting the focus of drug discovery initiatives so that therapeutic approaches for treating alcohol abuse associated with stress can be improved.
|Effective start/end date||2/10/14 → 1/31/19|
- NIH National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Toll-Like Receptor 4
Magnetic Resonance Imaging