Effects of induced hypoprolactinaemia in the ram: plasma gonadotrophin levels, LH and FSH receptors and histology of the testis.
In order to investigate the effects of induced hypoprolactinaemia on gonadotrophin levels and testicular function in the ram, CB 154 was administered either in summer under natural photoperiod or in winter combined with a light regime stimulating prolactin release. Under natural photoperiod in summer, plasma FSH levels increased from 2.5 to 4 ng/ml in controls and from 2.5 to 8 ng/ml in CB 154-treated rams. Control and treated groups differed significantly (P less than 0.05) from the second week of treatment onwards. In the animals photostimulated in winter, treatment with CB 154 did not change plasma FSH levels; no effect of CB 154 on plasma LH levels was detected in either experiment. Treatment with CB 154 in summer led to an increase in the volumes of peritubular blood vessels and interstitial tissue. The number of Leydig cells per testis was significantly (P less than 0.05) increased in CB 154-treated rams. However, at the time of measurement, there was no change in the structure of the seminiferous tubules or in the production of germ cells. In winter in photostimulated animals, no effect of treatment with CB 154 was detected either on the structure of intestitial and tubular compartments or on spermatogenesis. The change in prolactin levels affected neither the number of LH receptors, expressed per Leydig cell, nor the number of FSH receptors, expressed per Sertoli cell, in the experiments. It is concluded that induced hypoprolactinaemia can modify the release of FSH in the ram and change the structure of the intertubular tissue but that it does not affect the number of LH and FSH receptors or impair spermatogenesis.
D000818:Animals; D001971:Bromocriptine / Q000494:pharmacology; D002452:Cell Count; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007985:Leydig Cells / Q000166:cytology; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D009929:Organ Size; D010775:Photic Stimulation; D011388:Prolactin / Q000097:blood*; D011956:Receptors, Cell Surface / Q000032:analysis*; D011962:Receptors, FSH; D011974:Receptors, LH; D012671:Seminiferous Tubules / Q000187:drug effects; D012756:Sheep / Q000097:blood*; D013091:Spermatogenesis / Q000187:drug effects; D013737:Testis / Q000187:drug effects / Q000473:pathology*
D011956:Receptors, Cell Surface; D011962:Receptors, FSH; D011974:Receptors, LH; D001971:Bromocriptine; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone