Effect of hyperprolactinemia induced by pituitary grafts or castration on porphyrin content of the mouse Harderian gland

The histology and porphyrin concentrations of Harderian glands and plasma prolactin levels were examined in B6C3F1 mice castrated or isografted with pituitaries in combination with the administration of bromocriptine (2-bromo-á-ergocryptine), a potent suppressor of prolactin. Four pituitaries were transplanted underneath the bilateral kidney capsules of each mouse. Furthermore, we investigated Harderian porphyrins and plasma testosterone levels in mice that were castrated or treated with neuroleptic butyrophenone (timiperone), a potent accelerator of prolactin, and treated concurrently with bromocriptine. Light microscopically, pituitary grafts increased the concretion of porphyrin pigments within the Harderian gland lumina. Pituitary grafts or castration increased both Harderian porphyrin concentrations and plasma prolactin levels compared with the intact control mice. In pituitary-grafted or castrated mice, bromocriptine distinctly prevented the rise in both porphyrins and prolactin levels. Administration of butyrophenone did not result in any marked change in testosterone levels, although Harderian gland porphyrins were significantly increased. The present results indicate that in mice prolactin stimulates the porphyrin production of the Harderian gland and has an important role in the regulation of Harderian gland porphyrins.