The Counterbalancing Effect of Follicle-Stimulating Hormone on the Antigonadal Activity of Prolactin in the Male Newt Triturus Cristatus Carnifex (Laur.)

Abstract

The administration of 100 i.u. ovine prolactin to male crested newts has been shown to block spermatogenesis by producing a zone of degeneration in spermatogonia which are about to change into primary spermatocytes (Mazzi, Vellano & Toscano, 1967).Since signs of inhibited function of adenohypophysial type II basophils, which may be regarded as producing follicle-stimulating hormone (FSH) (Mazzi, Peyrot, Anzalone & Toscano, 1966), had been observed in prolactin-treated animals, it was assumed that the antigonadal effect of prolactin was secondary to the inhibition of FSH-producing cells. To test this hypothesis, experiments involving the simultaneous injection of prolactin and FSH were carried out.On 13 June 1967, 40 male newts in full spermatogenetic activity were divided into four groups of ten. The first group served as controls; the second group received 100\p=n-\120 i.u. prolactin (ovine, NIH-P-S7) in 0\m=.\6 % NaCl solution, divided into four injections of 0\m=.\1ml. given every other day. The third group received prolactin plus 0\m=.\5 mg. FSH (ovine, NIH-FSH-S3) in the same solution. The fourth group was injected with saline solution only. The animals were killed 48 hr. after the last in¬ jection. The testes were fixed in Sanfelice's fluid, cut at 7 p and stained with light gr een-safranin.In both the non-injected controls and the newts injected with the solvent alone, spermatogenesis was normal, without a trace of degeneration in the late spermatogonia. In seven out of the ten prolactin-treated animals the expected antigonadal effect was observed, with the formation of a zone of degeneration. Two animals had atrophie testes containing proliferating protogonia and spermatogonia.In the ten animals injected with prolactin plus FSH, spermatogenesis seemed quite normal and there was no degeneration among late spermatogonia : the spermatogonia showed a higher mitotic rate than those of the controls.These results make it very likely that in the male-crested newt as in the domestic fowl (Bates, Riddle & Lahr, 1937 ;Nalbandov, 1946 ; Lofts & Marshall, 1958) prolactin exerts its antigonadal effect by inhibiting the adenohypophysial FSH-producing gonadotrophs.

The annual reproductive cycle of the Smooth newt (Triturus vulgaris) in England

“…Prolactin also stimulates migration to water ('water drive') at the beginning of the breeding season (Grant & Cooper, 1965;Vellano, Peyrot & Mazzi, 1967), and increases the specific gravity of individuals such that they become negatively buoyant in water (Moriya, 1982). Prolactin has an adverse effect, however, on spermatogenesis, blocking the division of spermatogonia into spermatocytes (Mazzi & Vellano, 1968). It seems that prolactin exerts this effect by inhibiting gonadotropin secretion by the adenohypophysis, because the block can be reversed if prolactin and gonadotropin are administered concurrently (Mazzi & Vellano, 1968).…”

“…Prolactin has an adverse effect, however, on spermatogenesis, blocking the division of spermatogonia into spermatocytes (Mazzi & Vellano, 1968). It seems that prolactin exerts this effect by inhibiting gonadotropin secretion by the adenohypophysis, because the block can be reversed if prolactin and gonadotropin are administered concurrently (Mazzi & Vellano, 1968). In urodeles, there is little specificity between luteinizing hormone and follicle-stimulating hormone in controlling spermatogenesis (Licht, 1979).…”

Hormonal Control of Meiosis Initiation in the Testis from Japanese Newt, Cynops pyrrhogaster

“…Prolactin (PRL) is associated with various reproductive phenomena in urodeles such as adaptation to reproductive environment, sexual behavior, development of reproductive organs and sexual characters (Chadwick, 1941;Kikuyama and Toyoda, 1999;Kikuyama et al, 1975;Kikuyama et al, 1986). In the crested newt, administration of ovine PRL induces spermatogonial cell death, while co-injection of follicle-stimulating hormone (FSH) prevents it (Mazzi et al, 1967;Mazzi and Vellano, 1968). In the Japanese red-bellied newt, intraperitoneal injection of ovine PRL induces pyknotic degeneration of spermatogonia in the cysts situated adjacently to the boundary line between zones of spermatogonia and spermatocytes ( Fig.…”

Annual and daily serum aldosterone and catecholamine patterns in males of the Italian crested newt,Triturus carnifex(Amphibia, Urodela)

“…In T. carnifex, some studies evidence the presence of a correlation between some events of the reproductive cycle and the activity of the adrenal gland. Follicle-stimulating hormone (FSH), regulating spermatogenesis in amphibians (Galgano 1942(Galgano , 1943Mazzi & Vellano 1968) stimulated corticosteroid and catecholamine release from the newt adrenal gland, probably in order to produce the increase in metabolism necessary for spermatogenesis (Gay et al 2008). In this species, the presence of large amounts of epinephrine in the chromaffin cells coincides, during the February-April period, with the breeding season, and during the SeptemberNovember period with the beginning of both the luteinizing hormone (LH) synthesis cycle and the secondary sex characteristics cycle (Laforgia & Capaldo 1991).…”