Abstract
The neurohypophyseal hormone arginine vasopressin (AVP) and oxytocin, are mainly synthesised in the magnocellular neurosecretory cells of the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) of the hypothalamus. Various kinds of stress cause neuroendocrine responses such as corticotrophin-releasing hormone (CRH) or AVP release from parvocellular neurosecretory cells in the PVN and activation of the hypothalamo-pituitary adrenal (HPA) axis. Recently, we generated transgenic rats expressing an AVP-enhanced green fluorescent protein (eGFP) fusion gene in AVP-containing neurosecretory cells. Stress-induced AVP-eGFP changes in the hypothalamus of this transgenic rats are regulated by glucocorticoid in negative feedback loop in the hypothalamus and vary accordingly. In endotoxin-shocked rat AVP-eGFP fluorescence appeared in the parvocellular CRH neurons of the PVN and formalin-induced nociceptive stress increased magnocellular neurons of PVN as well as parvocellular neurons. Although adjuvant arthritic (AA) rat also revealed an increased AVP-eGFP fluorescence in both magnocellular and parvocellular neurons of the PVN, intensity and area of the fluorescence differed with formalin-induced nociceptive stress. We propose that AVP-eGFP transgenic rats represent a useful animal model for further understanding of physiology and biology of AVP expression in the hypothalamo-pituitary system under various kinds of stress, in particular acute and chronic inflammatory stress.
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