Effect of streptozotocin-diabetes on thymus of normal and adrenalectomized rats

The injection of streptozotocin in intact or adrenalectomized rats produced a decrease in the number of thymus lymphoid cells. Bovine serum albumin gradient analyses of thymocytes from control, adrenalectomized, adrenalectomized-diabetic and diabetic animals showed variations in the mature/immature cell ratio. No remarkable changes in the distribution of the different thymocyte subpopulations were observed.     

Measurement of inactive renin in normal, nephrectomized, and adrenalectomized rats.

In a new method for measurement of inactive rat plasma renin, the trypsin generated angiotensin I immunoreactive material, which was HPLC characterized as similar to tetradecapeptide renin substrate, is removed by a cation exchange resin before the renin incubation step. The method also corrects for trypsin destruction of endogenous angiotensinogen by the addition of exogenous angiotensinogen. When measured with this method inactive renin in rat plasma decreased after nephrectomy and increased after adrenalectomy. This is in accordance with findings in humans. A sexual dimorphism of prorenin (inactive renin) in rat plasma, similar to that reported in humans and mice, was demonstrated. Thus, inactive renin in the rat is no exception among species, and the rat might be a suitable animal model for further studies dealing with the physiology of prorenin in plasma and tissues.     

Parathyroidectomy and the induction of thymic atrophy in normal, adrenalectomized and orchidectomized rats

Parathyroidectomy or thyroparathyroidectomy in the male rat results in the severe atrophy of the thymus gland. This effect is not mediated by a secondary release of the cytolytic adrenal or gonadal steroids since it also occurs in adrenalectomized and orchidectomized animals. The loss of the parathyroid gland decreases the flow of thymic lymphocytes into mitosis; this inhibition of cell production leads to the marked decline in thymic weight. The effect can be partially prevented by administration of parathyroid hormone or calcium gluconate.