V. Mazzi

Prolactin and sexual behaviour in the crested newt (Triturus cristatus carnifex Laur.)

Abstract In an attempt to elucidate the possible prolactin involvement in sexual behaviour in the male crested newt, we have devised three experimental approaches: (1) hypophysectomy followed by replacement therapy with prolactin; (2) ectopic pituitary autograft; and (3) treatment with ergocryptine. After hypophysectomy (1), the percent time spent in courtship falls rapidly and is restored partially only by exogenous prolactin. In the short-term ectopic pituitary autograft (2), the enhanced release of endogenous prolactin triggered by the operation exerts a stimulatory effect on sexual behaviour. Courtship behaviour declines in the subsequent days. In long-term operated animals, spermatophore deposition is suppressed and concurrent testes regression takes place. After ergocryptine treatment (3), the percent of time spent in courtship decreases and is restored partially by exogenous prolactin. Hence prolactin appears to control sexual behavior in the crested newt, although other hormones seem to be involved in this mechanism. The occurrence of a synergism between prolactin and gonadal hormones in sustaining sexual behaviour in the crested newt is suggested. The action of prolactin on peripheral organs also is discussed.

Tail height, a prolactin-dependent ambisexual character in the newt (triturus cristatus carnifex Laur.) ☆

Abstract In castrated as well as in castrated and thyroidectomized Triturus cristatus carnifex adults from both sexes, prolactin administration alone (100 IU per newt), unlike LH or TSH, was seen to promote the increase in tail height, which is a seasonal gonadal hormones-independent ambisexual character. The same effects were seen to be exerted in the summer, or in aestivating normal newts by exogenous prolactin, or by treatments enhancing endogenous prolactin production, such as a drop in temperature and ectopic pituitary autografts. The naturally occurring seasonal variations in tail height parallel the circumannual prolactin level variations and water drive. Consistent changes are entailed by prolactin in both the fin connective axis (swelling and pigment redistribution in chromatophores) and the epidermis (acceleration of the mitotic rhythm and slowing down of keratinization processes). The present results lead us to conclude that the seasonal ambisexual character here investigated, the height of the tail, is prolactin dependent. The parallelism between water drive and tail height variations is stressed.

Antigonadal effects of prolactin in adult male crested newt (Triturus cristatus carnifex Laur.)

Abstract In adult estivating male newts ( Triturus cristatus carnifex Laur.) the administration of 100 IU of prolactin (ovine, N.I.H. P-S-7; “Luteolactin” Richter) elicits the same effects as those occurring naturally at the onset of the declining phase of spermatogenesis, i.e., water drive, and cessation of spermatogenesis following the pycnotic degeneration of spermatogonia that are about to change into primary spermatocytes. It is suggested that the latter phenomenon is due to the inhibition of the production of pituitary FSH by prolactin.

Identification by immunofluorescence of prolactin-producing cells in the hypophysis of the newt, Triturus cristatus carnifex Laur

Abstract In sections of the pituitary of the newt treated with fluorescent antiprolactin globulin, a green fluorescent antigen-antibody complex is present only in the acidophilic cells localized in the dorsocentral region of the distal lobe. These cells are identifiable with type I acidophils according to Mazzi (1949) and with type II acidophils according to van Oordt (1968) . These results are in keeping with the observation that purified newt prolactin obtained by polyacrylamide disc electrophoresis reacts immunologically with rabbit antisheep prolactin antiserum.

Gonadotropin stimulation by chronic administration of synthetic luteinizing hormone-releasing hormone in hypophysectomized pituitary grafted male newts

Abstract Chronic administration of synthetic LH-RH (0.5 μg/8 g body weight per day) directly into the graft area in hypophysectomized newts bearing a pituitary autograft results in an increase in testis volume and a recrudescence of spermatogenesis. In two cases round spermatids were formed. In LH-RH-treated animals the graft appears better preserved and richer in type II basophils (presumed gonadotropic cells). The height of the caudal fin (a prolactin-dependent ambisexual character), is more developed in saline-treated than in LH-RH-treated animals.

Ricerche istochimiche e al micro scopio elettronico sui tubi malpighiani di Dacus oleae Gmel.

SummaryThe Dacus oleae larva possesses four Malpighian tubules, two anterior and two posterior ones, which in pairs enter into a ureter. Before opening into the gut, at the level of the transition zone between the mid- and hindgut, each ureter is dilated into an ampulla.The anterior tubules are divided into four regions: distal, transition, middle and proximal ones: while in the posterior tubules only middle and proximal segments are detectable. The distribution of the enzyme systems is indicated in Fig. 3, while the ultrastructural organization which is typical of the cells composing the different regions is schematically represented in Fig. 1. According to the ultrastructural and enzymatic findings, and the discussion on this subject in the literature, the authors are led to assume that in the distal segment occurs the segregation of uric acid, urates and calcium salts. In the transition segment, and still more in the intermediate one, an indiscriminate transport of water and solutes occurs from the haemocoel into the lumen of the tubule by pinocytosis. A fraction of the catabolites is precipitated as chromolipoidal pigments. The transition stages between cytosomes and pigment are described. Along with secretory phenomena the resorption of useful substances occurs in the proximal region. A similar function is performed by the ureter. In the ampulla, which is characterized by a conspicuous system of deep tubular infoldings both at the apical and basal surfaces of its cells, a massive water resorption is presumed to occur.

The effect of synthetic luteinizing hormone releasing hormone on ovulation in the crested new

Abstract Six micrograms of synthetic LH-RH administered by perifusion of the pituitary in situ caused ovulation in winter female newts. A minor effect was obtained through intraperitoneal injection of 24 μg of the hormone. No effect was obtained by means of perifusion of ectopic pituitary autograft or infusion of the hormone into the third ventricle.

Prolactin and Reproduction

In this review we set out to examine the state-of-the-art research into the effects of prolactin (PRL) on various aspects of reproduction in anamniote vertebrates and reptiles. As an introduction, we will examine our knowledge of PRL receptors from a comparative viewpoint (see also Ensor61).

A Golgi study of the hypothalamus of Actinopterygii

SummaryThe preoptic area of a primitive actinopterygian, the polypteriform, Calamoichthys calabaricus Smithi, and of the teleost, Anguilla anguilla L., have been studied by Golgi and other neurohistological and histochemical methods. In the preoptic area two regions can be recognized: a cell rich median region and a lateral one, composed mostly of fiber systems. After Golgi staining a varied population of neurons is seen, including: (1) magnocellular neurons, endowed with a number of dendrites and an axon emerging from the main dendritic shaft; (2) lophodendritic tufted or pyriform neurons of variable morphology (often of the midget type); (3) cerebrospinal fluid contacting neurons; (4) bipolar and horizontal neurons. Of relevant interest is also the observation of commissural neurons, of a distinct precommissural nucleus, and of bipolar neurons, the axons of which course toward the ventral hypopallium.

Sodium and potassium metabolism in the new (Triturus cristatus carnifex L.). IV. Investigations on hypophysectomized males bearing an adenohypophysial heterotopic chronic autograf

Changes in electrolyte metabolism and in renal alkaline phosphatase activity have been investigated in hypophysectomized male newts bearing an adenohypophysial heterotopic chronic autograft. After 4 months the neurohypophysis had regenerated and the interrenal glands showed conspicuous alterations as compared with control animals. In addition the following results were obtained in the operated animals: a significant increase in muscle water content; a significant increase in muscle sodium content; a decrease in muscle potassium content, which was statistically significant only when related to wet weight; no significant changes in total net sodium and potassium exchange; a significant decrease in renal alkaline phosphatase activity. These findings suggest that the release of neurohypophysial hormones in the hypophysectomized newts with an adenohypophysial autograft was almost normal, that glucocorticoid secretion decreased and that mineralocorticoid secretion may have increased. Normal release of mineralocorticoids, inadequately counterbalanced by glucocorticoids, is also a possibility.