The influence of ACTH and cortisol upon skin homografts in the rat

Homografts of skin exchanged between two strains of rat survive for an average of 8·8 days.

Survival time is increased to 14·1 days by the daily administration (beginning on the day following operation) of 4·0 mg cortisol, but 2 i.u. ACTH (Cortrophin 'Z') daily has no effect (survival time = 9·0 days).

If, however, treatment with ACTH is begun 28 days before operation the homografts survive for 17 days (Cortrophin 'Z') and for 11·4 days (Acthar gel).

The normal processes of wound repair are slowed down in proportion to the influence of treatment on the immunity reaction.

The results conform to the view that prolonged treatment with ACTH alters the ratio of cortisol/corticosterone secreted by the adrenal cortex.

Effects of oestrogens and ACTH on the adrenals of the guinea-pig compared with those in the rat

1. In female guinea-pigs the total cholesterol in the adrenal glands was significantly depressed by stilboestrol (SB). Oestradiol (Oe) did not produce a significant fall in adrenal cholesterol, and the levels in the serum and liver were unchanged by either treatment.

2. The effects of SB and Oe have been compared in the guinea-pig and rat.

(a) In both species adrenocorticotrophic hormone (ACTH) caused a fall in adrenal ascorbic acid. In the rat, but not in the guinea-pig, there was also a fall after treatment with SB and Oe.

(b) In the rat SB caused severe morphological changes in the adrenal glands and great depletion of their lipid content. By contrast, in the guinea-pig, even using five times the dose given to the rat, morphological changes in the adrenals were minimal and there was little depletion of fat.

(c) Oe did not produce marked morphological changes in either species, but it caused great depletion of fat in the adrenal glands of the rat, and, by contrast, only a little depletion in the guinea-pig.

(d) No severe changes were observed in the livers and kidneys in either species following treatment with ACTH, SB or Oe.

These experiments emphasize the large differences in the response of these two species to treatment with oestrogens.