Antidiuretic activity in the neurohypophysis of rats after adrenalectomy and replacement therapy.

Abstract

SUMMARY 1. The content of antidiuretic hormone in the neurohypophysis, the weight of the neurohypophysis and the daily output of urine were studied in the following groups of rats: intact rats which received 2 g NaCl/100 ml. as drinking fluid; adrenalectomized rats; sham-adrenalectomized rats; adrenalectomized rats injected with deoxycorticosterone acetate or aqueous adrenocortical extract, lipo-adrenal extract, cortisone or cortisone and noradrenaline; adrenalectomized rats to which sodium chloride had been administered; and adrenalectomized rats which received both sodium chloride and adrenocortical hormones. 2. The antidiuretic hormone content of the pars nervosa (per mg wet gland) of intact rats to which salt had been given was about half of that of controls without extra salt. There was no significant difference between the mean daily urine volumes of the two series. 3. In adrenalectomized and sham-adrenalectomized rats, 2 days after the operation, the hormone content of the pars nervosa was reduced. In adrenalectomized animals this decrease in antidiuretic activity persisted; in sham-operated rats the antidiuretic activity had increased 5 days after the operation and was fully restored after 7. The daily urine output of the adrenalectomized animals was about one-third of that of intact controls. 4. No significant increase in antidiuretic hormone content of the neurohypophysis occurred when adrenocortical preparations were injected into adrenalectomized rats, but the urine volume of these animals increased. 5. Salt alone, in low or high doses, both orally or subcutaneously administered, increased the amount of antidiuretic principle in the pituitaries of adrenalectomized rats, but control levels were not attained. The daily urine volume of these animals returned to normal. 6. Combined treatment of adrenalectomized rats with salt and adrenocortical extract or cortisone, but not with salt and deoxycorticosterone acetate, led to full restoration of the antidiuretic hormone content of the neurohypophysis. These treatments also produced a rise of the daily urine volume above that of intact controls. 7. In adrenalectomized rats a close relationship was found between the degree to which the various treatments raised the hormone content of the gland and that to which they increased the daily output of urine. 8. The significance of the results is discussed, and the impossibility of drawing conclusions from them about neurohypophysial function in adrenocortical deficiency is stressed.