Cerebral Neurochemical Mechanisms in Stress and Anxiety
Annual technical rept. 1 Feb 1993-31 Jan 1994
LOUISIANA STATE UNIV MEDICAL CENTER SHREVEPORT
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Investigations are concerned with the cerebral mechanisms involved in stress. Current experiments focused on the locus coeruleus noradrenergic LC-NE system. In vivo microdialysis studies showed that both hemodynamic stress induced by nitroprusside, and electric footshock increased the apparent release of norepinephrine NE In the hypothalamus and prefrontal cortex. The potential role of corticotropin-releasing factor CRF In the activation of the LC-NE system was investigated. CRF Infused into the LC, but not in surroyncring brain structures such as the par nucleus, increased the apparent synaptic release of cortical NE. This effect was largely ungateral, and to Involve CRF-receptors. We have performed preliminary studies using the new technique of In vivo voltammetry. These studies have confirmed the increased appearance of extracellular NE following nitroprusside infusion. The superior time resolution of this technique indicated that the NE response nitroprusside was short-lived. The classic benzodiazepine anxiolytic, chlorcgazepoxide CDP, appeared to diminish the. NE response to footshock and may also affect basal NE release. Behavioral studies indicated that activation of NE system with idazoxan almost completely inhibited stress-induced ultrasonic vocalization, with relatively small changes in stress-induced freezing. We failed to find any consistent effects of 6-hydroxydopamine-induced lesions of the dorsal noradrenergic bundle, although vocalization was slightly potentiated. Stress, Anxiety, Norepinephrine microdialysis, Benzodiazepine, Voltammetry, Behavior.
- Medicine and Medical Research