Influence of Prolactin and Pituitary Isografts on Spermatogenesis in Dwarf Mice and Hypophysectomized Rats

Abstract

This work was undertaken to study the influence of purified prolactin on spermatogenesis in hypophysectomized rats with or without testosterone propionate maintenance therapy and in prolactin-deficient hereditary dwarf mice. In addition some dwarf mice were given heterotopic isografts of non-dwarf mice pituitaries. In rats, 25 i.u. ovine prolactin given daily for 33 days had no effect on the maintenance of spermatogenesis. In untreated dwarf mice spermatogenesis progressed to completion but had a low yield due to cell loss, especially during premeiotic divisions. Both 10 i.u. prolactin daily for 28 days and pituitary grafts resulted in marked stimulation of spermatogenesis. The number of preleptotene and pachytene spermatocytes and step 7 spermatids was significantly increased in both inbred and F1 dwarf mice regardless of age. Since seminal vesicles were also considerably heavier in treated dwarfs, it was concluded that the observed stimulation of spermatogenesis was most likely due to elevated testicular androgen production indicating that, in the male mouse, prolactin may be involved in pituitary regulation of Leydig cell function.

Studies on the Minimal Dosage of Melatonin Required to Inhibit Pineal Antigonadotrophic Activity in Male Golden Hamsters

“…A number o f recent reports have proposed that prolactin may act synergistically with LH or testosterone to stimulate growth o f the sexual organs (Bartke et al, 1970;Moger and Geschwind, 1972). Without sufficient titers o f prolactin these organs in the male hamster may involute.…”

Prolactin and Leydig Cell Responsiveness to LH/hCG in the Rat

“…The dwarf mouse has a genetically linked deficiency in prolactin and growth hormone secretion, a condition which is associated with testicular failure including a complete arrest of spermatogenesis [2]. Prolactin treatment was found to reverse these changes and initiate spermatogenesis [5] an effect which was associated with the stimulation of certain key steroidogenic enzymes in the Leydig cell [IS, 191, and an assumed elevation of plasma testosterone levels. Subsequently the concept developed that prolactin was not acting alone but synergistically with LH, since the combined treatment with prolactin and LH in hypophysectomized rats stimulated the weight of the accessory sex glands [ 171 and plasma testosterone levels [ 141 significantly more than with either alone.…”

Hypoprolactinemia as Related to Seminal Quality and Serum Testosterone

“…animals restores their fertility [5]. In hypophysectomized, castrated, adult male rats, prolactin enhances the response of prostate to androgen treatment [28].…”