CONCOMITANT CHANGES OF MESSENGER-RIBONUCLEIC-ACID LEVELS OF SECRETOGRANIN-II, VGF, VASOPRESSIN AND OXYTOCIN IN THE PARAVENTRICULAR NUCLEUS OF RATS AFTER ADRENALECTOMY AND DURING LACTATION

In situ hybridization was used to study the mRNA levels for secretogra nin II and VGF in comparison with those of oxytocin and vasopressin in the hypothalamus of rats. VGF is a widespread constituent of large de nse core vesicles which is selectively induced in PC12 cells by nerve growth factor. After adrenalectomy the mRNA levels of secretogranin II , VGF and vasopressin were increased 4- to 5-fold in the parvocellular neurons of the paraventricular nuclei. In lactating rats the message for oxytocin and secretogranin II were significantly elevated in the m agnocellular neurons of the paraventricular and supraoptic nuclei, whe reas for VGF only a smaller non-significant increase was observed. As shown by immunoelectron microscopy secretoneurin (a peptide derived fr om secretogranin II) and oxytocin are co-stored in the large dense cor e vesicles of the hypothalamo-neurohypophysial neurons. These results demonstrate that stimulation of both parvo- and magnocellular neurons of the hypothalamus induces a concomitant increase of the messages for secretogranin II and VGF together with those of vasopressin and oxyto cin.