ACTIVATION OF OXYTOCIN-CONTAINING NEURONS OF THE PARAVENTRICULAR NUCLEUS (PVN) FOLLOWING GENERALIZED SEIZURES

Due to the complex nature of generalized limbic seizures, marked distu rbances in physiological homeostasis occur Accompanying the motor mani festations which characteristically are associated with generalized li mbic seizures, alterations in neuroendocrine, behavioral, and autonomi c functions may be observed. The paraventricular nucleus (PVN) of the hypothalamus is known to play a significant role in such neuronal resp onses to stressful stimuli; however, the effect of seizures on hypotha lamic neurons is unknown. We have used the immunocytochemical detectio n of the Fos protein to anatomically identify neurons in the PVN which are activated following generalized limbic seizures. To induce seizur es, rats received intraperitoneal injections of kainic acid or were ki ndled ham the entorhinal cortex. We have demonstrated that elicitation of generalized Limbic seizures induces a dramatic number of neurons i n the PVN to express the Fos protein. Numerous Fos-immunolabeled neuro ns were identified in both the parvicellular and magnocellular compone nt of the PVN. In the latter, this study clearly reveals a preferentia l and selective activation of oxytocin-containing neurons, and it exte nds and supports the hypothesis that oxytocin plays a role in the body 's response to specific stress paradigms. Data suggest that an activat ion of the oxytocin neuronal system may be part of the adaptive mechan ism that enables the hypothalamus to modulate and maintain an adequate response to stressors (e.g., generalized seizures) to regain homeosta sis. (C) 1996 Wiley-Liss, Inc.