RT Journal Article
SR Electronic
T1 Release of Vasopressin within the Rat Paraventricular Nucleus in Response to Emotional Stress: A Novel Mechanism of Regulating Adrenocorticotropic Hormone Secretion?
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 7725
OP 7732
DO 10.1523/JNEUROSCI.16-23-07725.1996
VO 16
IS 23
A1 Carsten T. Wotjak
A1 Masaharu Kubota
A1 Gudrun Liebsch
A1 Alexandra Montkowski
A1 Florian Holsboer
A1 Inga Neumann
A1 Rainer Landgraf
YR 1996
UL http://www.jneurosci.org/content/16/23/7725.abstract
AB The effects of emotional stressors on the release of arginine vasopressin (AVP) and oxytocin (OXT) within the rat hypothalamus and the origin and physiological significance of AVP released within the hypothalamic paraventricular nucleus (PVN) were investigated. First, adult male Wistar rats with a microdialysis probe aimed at the PVN or the supraoptic nucleus were exposed to either a dominant male rat (social defeat) or a novel cage. Release of AVP within the PVN was significantly increased in response to social defeat but not to novelty. In contrast to an activation of the hypothalamic–pituitary–adrenal (HPA) system, neither stressor stimulated the hypothalamic–neurohypophysial system (unchanged plasma AVP and OXT and unchanged release within the supraoptic nucleus [AVP] and the PVN [OXT]). Next, we demonstrated by simultaneous microdialysis of the suprachiasmatic nucleus and the PVN that AVP measured in PVN dialysates during social defeat was probably of intranuclear origin. Finally, a mixture of a V1 AVP and the α-helical corticotropin-releasing hormone (CRH) receptor antagonists administered via inverse microdialysis into the PVN caused a significant increase in the plasma adrenocorticotropic hormone (ACTH) concentration compared with vehicle-treated controls both under basal conditions and during social defeat, indicating inhibitory effects of intra-PVN-released AVP and/or CRH on HPA system activity. The antagonists failed to affect anxiety-related behavior of the animals as assessed with the elevated plus-maze. Taken together, our results show for the first time that AVP is released within the PVN in response to an emotional stressor. We hypothesize that this intranuclear release provides a negative tonus on ACTH secretion.