THE EFFECTS OF BROMOCRIPTINE AND PROLACTIN ON PORPHYRIN BIOSYNTHESIS AND MORPHOLOGY IN THE FEMALE HAMSTER HARDERIAN-GLAND

Porphyrin biosynthesis was examined in the Harderian gland of the fema le golden hamster by fluorometric assays of gland porphyrin content an d by measuring the activity of a rate-limiting enzyme for haem biosynt hesis, delta-aminolaevulinic acid synthase. Both porphyrin content and enzyme activity are high in normal female glands. Enzyme activity was lowered in females ovariectomised for 6 weeks, and both enzyme activi ty and porphyrin content were greatly lowered in ovariectomised female s given the dopamine agonist bromocriptine; this suppression could be prevented by simultaneous prolactin administration. Bromocriptine (but not ovariectomy alone) also masculinised the morphology of the Harder ian gland, resulting in the appearance of type II cells and polytubula r complexes; again, the simultaneous administration of prolactin preve nted masculinisation. The results support the hypothesis that while an drogens have an inhibitory effect on porphyrin synthesis within this m odel, prolactin may have a major facilitatory role.