Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Angiotensin II (Ang) injected intracerebroventricularly stimulates neurohypophyseal vasopressin (AVP) release into the peripheral circulation. As we have shown previously, central actions of Ang II in the rat forebrain are mediated by the AT1A receptor subtype. In the present paper, we attempted to clarify the cellular localization of the AT1A receptor mRNA in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei, in order to reappraise the conflicting data on the nature of the angiotensin II receptor involved in Ang induced vasopressin release. For this purpose, double in situ hybridization was performed using a radioactive AT1A receptor riboprobe and a digoxygenin labeled AVP oligoprobe, and immunohistochemical localization of the glial marker glial fibrillary acidic protein (GFAP) on the same brain slice. The results show neuronal expression of AT1A receptor mRNA mainly in dorsal and medial parvocellular parts of the PVN, its localization in some magnocellular PVN neurons and the absence of its expression in AVP producing neurons either in the PVN or in the SON. Thus, while indirect evidence indicates the involvement of the AT1A receptor subtype in the regulation of CRH and oxytocin release, the stimulation of vasopressinergic neurons is likely due to indirect mechanisms, or to a yet unknown type of angiotensin receptor.
 ...
PMID:Comparative expression of vasopressin and angiotensin type-1 receptor mRNA in rat hypothalamic nuclei: a double in situ hybridization study. 875 Aug 69

The subfornical organ and organum vasculosum laminae terminalis represent neuroglial circumventricular organ structures bordering the anterior third cerebral ventricle. Owing to the absence of the blood-brain barrier, the cellular elements of the subfornical organ and the organum vasculosum laminae terminalis can be reached by circulating messenger molecules transferring afferent information. As demonstrated for the control of extracellular fluid composition, the circulating hormone angiotensin II acts on these sensory circumventricular organs to induce drinking, elevated peripheral resistance and neurohypophyseal hormone release via interaction with membrane-spanning receptor proteins. To characterize the cell-specific distribution of angiotensin II receptors within the circumventricular organs, primary cell cultures derived from the subfornical organ or organum vasculosum laminae terminalis of five- to six-day-old rat pups were used to measure alterations in intracellular calcium at the single cell level. Neurons and astrocytes were identified by immunocytochemical staining for specific marker proteins. Bath application of angiotensin II (10(-10)-10(-6) M) dose-dependently induced calcium transients in neurons (19.6%) and astrocytes (15.7%), and angiotensin II threshold concentrations to elicit intracellular calcium signalling proved to be one order of magnitude higher in astrocytes as compared to neurons (10(-9) M). At angiotensin II concentrations higher than 10(-7) M, pronounced desensitization of the angiotensin II receptor occurred. Employing the angiotensin II receptor antagonists losartan (DUP-753; AT1-receptor) and PD-123319 (AT2-receptor), exclusive expression of the AT1 receptor subtype coupled to intracellular calcium concentration signalling could be demonstrated for neurons and astrocytes. In all cells examined, the angiotensin II-evoked increase in intracellular calcium concentrations could be fully suppressed in the absence of extracellular calcium. Co-activation by angiotensin II and other agents (vasopressin, its fragment 8-arginine-vasopressin(4-9), oxytocin, endothelin) was indicated for subfornical organ neurons and organum vasculosum laminae terminalis astrocytes.
 ...
PMID:Angiotensin II-induced calcium signalling in neurons and astrocytes of rat circumventricular organs. 962 48