REGENERATION OF ADRENAL-CORTICAL TISSUE AFTER ADRENAL AUTOTRANSPLANTATION

This study tested the possibility of adrenal autotransplantation in ra ts. Since the cortex and the medulla of the adrenal gland were from di fferent origin embriologically, either whole adrenal glands (ADR), or capsule and cortex (CAP) or medulla (MED) were autotransplanted in the subcutaneous tissue. The functions of regrated adrenal nodules were t ested by measuring plasma corticosterone levels every fortnight. At th e end of 9 weeks the rats were exposed to hypovolemic shock followed b y naloxone injection to reverse the shock response. Results showed tha t rats transplanted with either cortex or whole adrenal started secret ing corticosterone at 5 weeks post-transplantation (107.73 +/- 21.98 n g/ml, 126.04 +/- 48.41 ng/ml, respectively). Corticosterone levels inc reased to the value which were not significantly different from contro l by 9 weeks post-transplantation. However, rats transplanted with adr enal medulla showed very low corticosterone levels. Nine weeks post-tr ansplantation, the mean blood pressure (MBP) of the CAP group was 135 +/- 13 mmHg and was not significantly different from sham-operated con trols, whereas MBP of MED group was significantly lower than sham-oper ated animals (99 +/- 11 mmHg versus 141 +/- 9 mmHg). The MBP of the AD R group was also lower compared to sham-operated controls (112 +/- 17 mmHg P < 0.05). The MBP of the adrenal group was not statistically sig nificant compared to the CAP group. After 1% body weight haemorrhage, the MBP decreased significantly in ADR (45 +/- 5 mmHg, P < 0.05) and M ED group (36 +/- 9 mmHg, P < 0.001) compared to sham-operated rats (78 +/- 11 mmHg) but not in the CAP (56 +/- 9 mmHg). It was concluded tha t autotransplanted whole adrenal or adrenocortical tissues survived su bcutaneously and produced sufficient corticosterone to alleviate haemo rrhagic shock. Adrenal medullary tissue failed to regenerate subcutane ously and the presence of adrenal medullary tissue may suppressed the growth of transplanted adrenal gland.