Deterioration of male reproductive functions in hyperprolactinaemia

Since the early seventies, chronic hyperPRLaemia due to hypothalamic-pituitary disorders, drug abuse, hypothyroidism or other causes, has been recognized as a cause of reproductive dysfunctions in both women and men. Possible mechanisms by which PRL exerts its effects on male reproductive functions have been extensively studied during the last two decades, but the mode of PRL action on reproductive functions has not been clarified by these studies. Mter an introduction on the physiological significance of PRL in vertebrates and the possible molecular processes involved in PRL action (chapter I), experimental models are discussed to study the effects of hyperPRLaernia on male reproductive functions in the rat (chapter II). This animal was used in the experiments presented in this thesis, because of the resemblance between the effects of hyperPRLaernia observed in rats and humans. During the experiments, the transplantable PRL-secreting tumour 7315b was employed as an experimental model to induce high serum PRL levels (2000- 5000 ng/rnl), comparable to those found in humans with hyperPRLaernia-associated impotence. Preceding the presentation of the data obtained from the experiments discussed in this thesis (chapters IV, V, VI, VII and VIII), male reproductive dysfunctions during hyperPRLaernia in the rat are reviewed (chapter III). Subsequently, aims and questions which are dealt with in this thesis are described.