Diurnal rectal temperatures and body weight as homeostatic indices in unilaterally adrenalectomized female Wistar rats

Abstract

There is growing interest in the investigation of the homeostatic adjustment of the remnant adrenal gland following unilateral adrenalectomy. This adjustment which is characterized by diverse physiological indices is critical to the survival of animals with unilateral adrenalectomy. This work studied the diurnal rectal temperature and body weight changes as physiologic indices for the evaluation of homeostasis in apparently healthy unilaterally adrenalectomized female Wistar rats. A total of twenty Wistar rats comprising ten adults (24 weeks) and ten growers (9 weeks) were used for this study. Each age class was randomly assigned into two groups of five rats each. The rats in one group from each age class were unilaterally adrenalectomized while the rats in the remaining groups were sham-operated (laparotomy only). The rats were weighed just before the surgery and at days 21 and 30 post-surgery. Also, from day 21 post-adrenalectomy, the morning and evening rectal temperatures were measured for 10 consecutive days. Body weight changes and the mean, maximum, minimum and ranges of morning and evening rectal temperatures were recorded. The results showed that after 21 days post-adrenalectomy, diurnal rectal temperature variations remained stable between 34.42±0.09 to 34.65±0.08 for the growers and 34.48±0.13 to 35.45±0.10 for the adults. Both adrenalectomized groups recorded increase in body weight. The increase in body weight of the adult adrenalectomized group occurred more within the first 21 days post-surgery (5.59±0.98 to 9.16±1.90) and stabilized by day 30 post-surgery (9.16±1.90 to 9.64±1.52). For the grower rats also, the unilaterally adrenalectomized rats showed a greater increase in weight gain (76.99±2.87) than their sham counterparts (control) (64.08±5.25) by day 30 post-adrenalectomy, but the difference was not statistically significant (p>0.05). We conclude that the result of this study has demonstrated that body weight changes could be a major homeostatic adjustment to unilateral adrenalectomy in rats.