The effect of the pineal gland on liver regeneration in rats

We investigated the influence of pinealectomy on liver regeneration after partial hepatectomy in rats. Methods: Thirty rats were allocated into four groups as follows: group 1 in which no operation was done (control), group 2 in which only midline scalp incision and craniotomy was performed (sham operation), group 3 in which pinealectomy was performed and pineal transplantation. Eight weeks later all the rats underwent 70% hepatectomy. Results: Hepatic regenerative capacity was observed 24 h after PH by bromodeoxyuridine incorporation into DNA and the mitotic index of hepatocytes. The bromodeoxyuridine labeling indices were 45.4, 35.8, 19.9 and 36.8 in groups 1, 2, 3 and 4, respectively. The mitotic indices of the same groups were 31.2, 28.7, 8.3 and 13.4, respectively. Both the bromodeoxyuridine labeling and mitotic indices were significantly lower in the pinealectomized rats than in the control and sham operation groups. Conclusions: These results suggest that the pineal gland stimulates liver regeneration after partial hepatectomy in rats.