UP-REGULATION OF VASOPRESSIN MESSENGER-RNA IN PARAVENTRICULAR HYPOPHYSIOTROPHIC NEURONS AFTER ACUTE IMMOBILIZATION STRESS

Cellular levels of vasopressin (VP) and corticotropin-releasing factor (CRF) mRNAs were determined in the rat hypothalamic paraventricular n ucleus after acute immobilization stress. Messenger RNA levels were me asured by in situ hybridization histochemistry using S-35-labeled synt hetic DNA oligonucleotide probes and quantitative autoradiography. Ana lysis of histograms related to density values revealed that two hours after immobilization the average cellular VP and CRF mRNA levels were significantly increased (145 +/-30.3 and 68 +/- 21.3%, respectively, a bove control values). Moreover, the number of VP-expressing parvicellu lar neurons was doubled in stressed rats relative to controls. These r esults indicate that single acute immobilization stress is sufficient to up-regulate VP as well as CRF mRNA production in the hypothalamic C RF-neurosecretory system.