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

The hypothalamus is one of the most studied areas of the central nervous system. Many of its functions are understood and there is an extensive literature on its role in the control of pituitary hormone secretion, autonomic nervous system activity, regulation of salt, water and food ingestion, body temperature regulation and aspects of behaviour. Although the role of the hypothalamus in the control of pituitary secretion was postulated in the early 1900s, the chemical nature of these control mechanisms has only been documented in the last few years. The opioid peptides represent one particular family of chemical compounds which have been shown to have many effects on pituitary hormone secretion. Exogenous opioids inhibit the neurosecretion of both vasopressin and oxytocin from the posterior pituitary neurosecretory terminals of hypothalamic cell bodies. Opioids also have major actions on the secretory activity of the anterior pituitary which has no innervation from the hypothalamus, but which is regulated by blood-borne factors in the hypophyseal portal circulation which runs from the median eminence of the hypothalamus. It was therefore of considerable interest when it was discovered that endogenous opioid peptides could be detected both in the neurohypophyseal system and in cells which project into the median eminence. The simple presence of a peptide in a neurone does not necessarily imply a function. If, however, we can demonstrate that regulation of the synthesis of the peptide occurs in a manner which corresponds with the expected role of the agent, this provides powerful data in support of a genuine physiological function. The elucidation of the genomic structure of the precursors for the three endogenous opioid peptides has provided us with the ability to measure mRNA for these peptides in defined areas of the brain and to assess their response to appropriate stimuli. Not only does mRNA for the endogenous opioid dynorphin coexist in the same cells as vasopressin but we have now been able to demonstrate that stimuli to vasopressin secretion also result in a markedly increased accumulation of dynorphin mRNA. Similarly, previous studies have shown that opioid peptides derived from another precursor--pro-enkephalin A--coexist with corticotrophin releasing factor in a different group of hypothalamic cells. We have now been able to demonstrate that stresses which result in an accumulation of corticotrophin releasing factor mRNA also result in increased pro-enkephalin mRNA in the same area. This considerably strengthens the hypothesis that endogenous opioids do play a significant role in the control of hypophyseal secretion.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The neuroendocrine paraventricular hypothalamus: receptors, signal transduction, mRNA and neurosecretion. 285 Mar 37

The distribution of FMRFamidelike peptides was studied in the nervous system of the lobster Homarus americanus by using immunocytochemical and radioimmunological techniques. By radioimmunoassay FMRFamidelike immunoreactivity (FLI) was found in low levels (ca. 1 pmol/mg protein) throughout the ventral nerve cord and in much higher amounts (60-100 pmol/mg protein) in the neurosecretory pericardial organs. Immunocytochemical studies showed FLI in approximately 300-350 cell bodies, and in distinct neuropil regions, neuronal fiber tracts, and varicose endings. Specificity of the immunostaining was tested by preabsorbing the antiserum with FMRFamide, with peptides having similar carboxyl termini to FMRFamide (Met-enkephalin-Arg-Phe, Phe-Met-Arg-Tyr-amide), with several amidated peptides (alpha-melanocyte-stimulating hormone, substance P, oxytocin), and with proctolin, a peptide found widely distributed in the lobster nervous system. Of these substances, only FMRFamide blocked the staining. In addition to the pericardial organs, significant levels of FLI were found in neurosecretory regions associated with thoracic second roots and in the connective tissue sheath that surrounds the ventral nerve cord. In all three regions, immunocytochemical studies showed the FLI to be localized to fine fibers and associated terminal varicosities lying close to the surface of the tissue, with no obvious target in their immediate vicinity. When examined at the ultrastructural level, the immunoreactive varicosities of the thoracic second roots and of the ventral nerve cord sheaths were found a few microns from the surface of the tissue and contained electron-dense granules. In the immunoreactive nerve cord sheath endings, in addition to the large, dense granules, small, clear vesicles were found. The appearance and location of these terminals suggest a neurohormonal role for FMRFamidelike peptides in lobsters. The observation that low levels of FLI are found in the hemolymph supports this suggestion. In addition, the localization of FLI to particular neuronal somata, fiber tracts, and neuropil regions suggests possible functional roles for these peptides in (1) integration of visual and olfactory information, (2) function of the anterior and posterior gut, and (3) the control of exoskeletal muscles.
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PMID:FMRFamidelike peptides of Homarus americanus: distribution, immunocytochemical mapping, and ultrastructural localization in terminal varicosities. 332 67