Abstract:

Objective To investigate the changes in structure and function of zona fasciculata and reticularis of adrenal cortex in castrated male rats, and explore the effect of low androgen on  the signal pathway of cyclooxgenase-2 (COX-2). Methods Thirty male SD rats aged 10 weeks were randomly divided into control group (n=8), castration group (n=11) and replacement group (n=11). Rats in control group received sham castration, those in castration group underwent castration, and those in replacement group were managed with testosterone undecanoate (50 mg/kg per month) after castration. Ten weeks later, serum samples were collected for determination of serum concentrations of testosterone (T), corticosterone (F), adrenocorticotrophic hormone (ACTH), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by radioimmunoassay, adrenal cortex tissues were obtained for observation of morphological changes in zona fasciculata and reticularis of adrenal cortex with HE staining by light microscopy and ultrastructural changes by transmission electron microscopy, and the expression of COX-2 mRNA in tissues of adrenal cortex and thoracoabdominal aorta was detected by RT-PCR. Results Serum T concentration in castration group was significantly lower than those in control group and replacement group （P<0.01）, and serum concentrations of F, ACTH, LH and FSH in castration group were significantly higher than those in control group and replacement group （P<0.05）. Cells in zona fasciculate and reticularis of adrenal cortex in castration group were larger, with bigger nuclei, more mitochondrion, better-developed smooth endoplasmic reticula and less lipid droplets. However, the morphology and ultrastructure of cells in zona fasciculata and reticularis of adrenal cortex in replacement group were similar to those in control group. The expression of COX-2 mRNA in adrenal cortex tissues in castration group was significantly lower than that in control group and replacement group (P<0.05), while the expression of COX-2 mRNA in aorta tissues in castration group was significantly higher than that in control group and replacement group (P<0.05). Conclusion There are hyperplasia and hyperfunction of zona fasciculate and reticularis of adrenal cortex and lower expression of COX-2 mRNA in adrenal cortex tissues in castrated male rats, and the increased expression of COX-2 mRNA in aorta tissues may be related to the vascular disease induced by low androgen.

Key words: low androgen, adrenal cortex, cyclooxgenase-2, blood vessel