Biosynthesis of neurohypophysial proteins in rats with hereditary hypothalamic diabetes insididus (brattleboro strain)

Abstract

The synthesis and axonal transport of neurohypophysial proteins were studied in rats with hereditary diabetes insipidus (DI) following injection of [35S]cysteine into the region of the supraoptic nucleus (SON). The defective rats possessed reduced amounts of neurophysin (mol. wt. 12,500) and of another polypeptide (mol. wt. 14,500), although their hypothalamic magnocellular neurones appeared to possess the normal mechanisms for axonal transport in the hypothalamo-neurohypophysial system. The synthesis and turnover of neurophysin are stimulated in DI rats. The pattern of incorporation of [35S]cysteine into neural lobe proteins in vitro differs between DI and control rats. The role of the neurophysin in DI rats as a vasopressin or an oxytocin ‘carrier’ is discussed.