Regulation of hypothalamic magnocellular neuropeptides and their mRNAs in the Brattleboro rat: coordinate responses to further osmotic challenge.

摘要: A paradigm was developed for the chronic osmotic stimulation of homozygous diabetes insipidus rats Brattleboro strain, a strain that fails to synthesize vasopressin. This study examines adaptation 2 sets coexisting peptide hormone magnocellular neurons in hypothalamoneurohypophyseal system (HNS) Long Evans (LE), heterozygote (HZ), and homozygote (DI) rats: (1) arginine8-vasopressin (AVP)/dynorphin (DYN) neurons, (2) oxytocin (OT)/cholecystokinin (CCK8) paraventricular supraoptic nuclei, which project posterior pituitary. The regimen intermittent salt-loading (CISL) involved replacement 2% saline normal drinking water 18 hr/d. protocol effectively increased plasma levels AVP OT LE HZ rats, DI maintained pituitary state depleted AVP, OT, CCK, peptides derived from pro-dynorphin: DYN 1-17, 1-8, B 1-13. ratio 1-17 1-8 content or LE, HZ, following 6 d CISL suggests preferential release during periods secretory activity. In response activity, mRNAs DYN, CCK 1.5-2-fold all 3 rat strains, with hormones displaying parallel increases. Mutant mRNA expressed at very low high levels, each these continuing be regulated by manner. These results suggest regulatory relationship between vasopressin are feedback-regulated most likely via osmolarity, modulated pro-dynorphin.