The effect of cervical sympathectomy on the pituitary and pineal endocrine system

: It was reported previously that continuous exposure to light in male rats increased serum luteinizing hormone (LH) and bilateral cervical sympathectomy inhibited such a change. In the present report, to examine the effect of cervical sympathectomy on the pineal endocrine function, 30 male rats were assigned to five groups. The control (C) group and the light (L) group underwent sham sympathectomy as well as sham pinealectomy. The sympathectomy (S) group underwent sympathectomy and sham pinealectomy. The pinealectomy (P) group and pinealectomy-melatonine (PM) group underwent sympathectomy and pinealectomy. The C group was kept under a normal circadian rhythm for 10 days, and the other groups were kept under continuous exposure to light for the same period. The PM group received subcutaneously 10 mg.kg-1 of melatonine every day. Serum LH levels were measured 10 days following these experiments. With regard to serum LH levels, the differences among C group, L group, and S group were similar to those previously reported. It was higher in P group (2.53 +/- 0.40 ng.ml-1) than in S group (1.58 +/- 0.61 ng.ml-1), and lower in PM group (2.08 +/- 0.31 ng.ml-1) than in P group. In conclusion, it is suggested that the endocrine activity of melatonine from the pineal gland plays an important role in the appearance of the effect of cervical sympathectomy.