Neurohypophysial Hormones in the Pars Nervosa of the Mouse with Hereditary Nephrogenic Diabetes Insipidus

Abstract

Vasopressor and oxytocic activities were detectable in the pars nervosa of mice with hereditary diabetes insipidus (DI Os/+ strain). This finding shows that the diabetes insipidus of DI mice is due to a primary defect of the kidney and not to vasopressin deficiency. Both activities of the DI mice were significantly higher than in normal mice (VII +/+) when the activities were expressed in terms of the individual. However, when the activity was expressed per mg of dry weight of the pars nervosa, the difference in oxytocic activity of the two groups seemed to be no longer significant, although vasopressor activity was still greater in the DI mice.

Salt and Water Metabolism and Neurohypophyseal Vasopressor Activity in Mice With Hereditary Nephrogenic Diabetes Insipidus

“…Similarly, Stewart Sc Stewart (1969), have bioassayed the neurohypophysial hormones of DI +/+ and DI Os/ + mice and irrespective of groups, their activity is equivalent to 140-200 mU for vasopressin and 80-120 mU for oxytocin. As these results are for DI Os/ + and DI +/+ combined, we cannot compare these results to our earlier results (Naik Sc Kobayashi 1971), nor the present ones. However, we can conclude from the results of Stewart 8c Stewart (1969) that these values are higher than those of VII +/+ and VII Os/+ mice.…”

“…The present results and the evidences of others (Naik 8c Valtin 1969;Naik Sc Kobayashi 1971;Stewart Sc Stewart 1969), therefore suggest very strongly that the diabetes insipidus in the 3 genotypes of DI mice, unlike the familial diabetes insipidus in the Brattleboro rats {Valtin 1967) is not due to a failure in the synthesis of ADH. Also, Naik Sc Valtin (1969) showed that the DI mice do not suffer from primary polydipsia as do STR/N mice described by Silverstein et al (1961).…”

“…The individual dried tissue was carefully weighed on a sensitive Mettler balance (Model M-5 S/A) and the weight was recorded. Previous procedure was followed for the extraction and bioassay of the individual gland (Naik Sc Kobayashi 1971). Vaso¬ pressor activities of the neurohypophysis extracts were estimated with the rat pressor method (Dekanski 1952), 8-lysin vasopressin (Sandoz) being used as the reference standard.…”

“…Naik Sc Sokol (1970) made a comparison of the hypothalamo-hypophysial neurosecretory system in the above 4 genotypes of mice and observed that there is a parallelism between the severity of the diabetes insipidus and the extent of hypertrophy of the neurosecretory system. The hypertrophied neurosecretory system is also accompanied by an increase of oxytocin and vasopressin (ADH) in the pituitaries of the DI Os/+ mice as compared to those of VII +/+ normals (Naik Sc Kobayashi 1971).…”

“…In certain domestic as well as laboratory animals, the physiological and pathological aspects of diabetes insipidus are better understood (dogs, Sloper et al 1967;Richards Sc Sloper 1969;rats, Valtin 1967;Sawyer et al 1964;mice, Falconer et al 1964;Naik Sc Valtin 1969;Naik Sc Sokol 1970;Naik Sc Kobayashi 1971;Stewart Sc Stewart 1969). But in human diabetes insipidus (hypothalamic or nephrogenic) the exact disorders in the hypothalamic hypo¬ physial neurosecretory system are not well understood (Forssman 1945;Martin 1959;Sloper 1969).…”