Mammalian Gonadotropins Research Articles

Competition for the in vitro binding of radioiodinated human follicle-stimulating hormone in reptilian, avian, and mammalian gonads by nonmammalian gonadotropins

Abstract Radioiodinated human FSH (125I-hFSH) was used to study the specificity of the gonadotropin binding sites of various reptilian, avian, and mammalian gonadal tissues by examining competitive interactions with several nonmammalian gonadotropins. All preparations of nonmammalian gonadotropins showed some activity in these radioligand assays, but wide variations in activities were evident depending on the source of the tissue and source of the hormone. Several cases of marked species specificity in binding were apparent: Nonmammalian hormones were relatively inactive with porcine granulosa cells; frog and snake hormones were relatively inactive in turtle tissues; and frog hormones were essentially inactive in avian tissues. FSH-LH specificity of binding determined with hormones of nonmammalian origin differed significantly from that previously described with the aid of mammalian gonadotropins. In particular, when tested with some tissues, three preparations of LH, from the turkey, sea turtle, and frog, were in some cases more active in competing for 125I-hFSH binding than preparations of FSH from the same species; this activity could not be readily accounted for by FSH contamination. These comparative data demonstrate the existence of considerable overlap in the binding characteristics of some species of FSH and LH; the observed differences probably reflect evolutionary changes in both gonadotropin binding sites and in the structure of the gonadotropins.

Introductory class exercises in experimental embryology usingXenopus laevis

Abstract This paper describes classical experiments of experimental embryology which may be repeated at class level using the early embryos of Xenopus laevis. The experiments demonstrate the effects of lithium on the early development of the nervous system, and the use of hypertonic salt solutions to produce exogastrulation. Both experiments involve the removal of the jelly coats around the embryo, and for this purpose a rapid chemical method using a cysteine hydrochloride/papain solution is described. Both experiments are theoretically important: the effects of lithium are used as evidence for the existence of an anterior-posterior gradient in the early embryo, while exogastrulation provides a convenient system for interfering with the primary inductive effect of the chordo-mesoderm, necessary for ectodermal neuralization. The procedure for obtaining fertile eggs from mature Xenopus specimens by injection of mammalian chorionic gonadotrophin is described.

Induced maturation and development of pinfish eggs

Pelagic eggs of pinfish ( Lagodon rhomboides), a common marine teleost found along the Atlantic coast of the southeastern United States, were induced to mature with mammalian gonadotropins and steroid hormones. The eggs were artificially fertilized and subsequent development of the eggs and yolk-sac larvae appeared normal. Yolk-sac larvae at 18°C utilized 50% of the yolk stores in 15 h, and of the oil droplet in 17.4 h.

Endocrine Control of Ovulation in Medaka (Oryzias latipes) and Ayu (Plecoglossus altivelis)

This study was undertaken to elucidate the endocrine control of ovulation in the medaka (Oryzias latipes) and the ayu (Plecoglossus altivelis). Among gonadotropins, salmon gonadotropin gave the best response in inducing in vitro ovulation of Oryzias oocytes and demonstrated a higher potency than mammalian gonadotropin, suggesting a degree of zoological specificity. Of the steroids, cortisol was very effective in inducing in vitro ovulation of Oryzias oocytes. Furthermore, ovulation cannot be induced in Oryzias oocytes dissected from their follicular tissues prior to exposure to gonadotropin, suggesting that the hormone acts first on the follicular envelope to produce effective agents (corticoids?) which are then responsible for ovulation. Application of a specific inhibitor (SU-4885) of 11β-hydroxylase resulted in inhibition of gonadotropin-induced ovulation, but did not affect ovulation induced by cortisol. The results suggest that corticosteroidogenesis in the follicular tissues is required for gonadotropin-induced ovulation. However, cortisol failed to induce in vitro ovulation of Oryzias oocytes removed from their follicular tissues. Thus, ovulation may be induced by secondary agents that are produced during corticoid biosynthesis or metabolism within the follicular envelope. Hirose et al. showed in 1974 that gonadotropin-treated mature ayu imbibed a greater quantity of water than control ayu, and that body weight increased by 3% in the hormone-treated fish. These results indicate that water ingestion and hydration of oocytes induced by gonadotropin may be an important process at ovulation. It has also been shown that during maturation and ovulation hydration is associated with ion movement (Na+). These phenomena may be related to the action of gonadotropin and/or corticoids and also occur at ovulation in the medaka. Such information may possibly yield additional clues regarding the mechanism of ovulation in fish and provide a solution to the practical problems of regulating ovulation.

Stimulation of In vitro steroid production in turtle ovarian tissue by reptilian, amphibian, and mammalian gonadotropins

Purified gonadotropins (FSH and LH) from a reptile, the snapping turtle, ( Chelydra serpentina), sheep, and bullfrog ( Rana catesbeiana) were used to investigate the hormonal control of ovarian steroidogenesis in vitro in four species of turtles ( Kinosternon, Sternotherus, Gopherus, and Chelydra). Follicle wall membrane (FW) from large follicles and stromal connective tissue (stroma) interspersed with small follicles were incubated separately for 4–16 hr, and steroids in extracted medium measured by radioimmunoassay after chromatography. Both FSH and LH from the turtle, mammal, and amphibian stimulated progesterone production in the four species of turtles. Turtle and ovine hormones also stimulated estradiol secretion. Experiments with LH antisera indicated that the steroidogenic actions of turtle and ovine FSH are intrinsic to the molecule.

Hormonal control of the nuchal hump in the cichlid fish Cichlasoma citrinellum

A nuchal hump (forehead swelling) develops in both male and female Cichlasoma citrinellum prior to spawning, and subsides shortly after spawning. Hump development is due to edema of the modified nuchal hypodermis. Fat stored in the same tissue does not contribute to prespawning hump development, although it may cause a residual, enduring hump. Plasma water increases slightly in fish with a nuchal swelling, indicating systemic water retention. The prespawning nuchal edema resembles preovulatory sexual skin swelling in monkeys. Nuchal hump development in males is gonad dependent. A hump could be induced with mammalian gonadotropins (HCG or ovine LH) in intact males but not in castrates. However, the steroid hormones testosterone, 11-ketotestosterone, 17β-estradiol benzoate, progesterone, hydrocortisone acetate, and aldosterone failed to induce a hump. A decline in the hump comparable to that occurring after spawning was induced by homogenate of C. citrinellum rostral pars distalis (8 r. p. d. per male fish); and a slight effect was obtained with ovine prolactin (2 daily injections of 7.5 μg/g). These results suggest that PRL secretion may inhibit the hump during the parental period.

Purification of turkey gonadotropins.

Turkey pituitaries, like mammalian pituitaries, were found to contain two gonadotropic factors. Highly purified LH was prepared and partially characterized. A potent turkey FSH was also prepared. Both gonadotropins were found to be similar to mammalian, turtle, and frog gonadotropins in terms of chromatographic behavior and the presence of carbohydrate. The turkey LH was found to be similar to ovine LH in amino acid composition but to contain significantly less carbohydrate than ovine LH. The sedimentation behavior of the turkey LH in neutral and acidic solutions suggested that this material is composed of subunits. Turkey gonadotropins appear to be more potent when assayed in non-mammalian systems than when tested in standard mammalian bioassays for LH and FSH. Study of the comparative endocrinology of pituitary gonadotropins requires the availability of purified hormones to obtain direct evidence on the number of gonadotropins and the nature of their physiological actions within each species, as well as the evolution of the gonadotropin molecule and the specilicities of hormone actions between species. There is considerable information on mammalian gonadotropins, but at present, information on purified non-mammalian gonadotropins is very limited. Reports have appeared on the purification of gonadotropins

Temperature dependence of the actions of mammalian and reptilian gonadotropins in a lizard

1. 1. The same marked temperature dependence is evident in the actions of both reptilian (snapping turtle) gonadotropin and mammalian gonadotropin (ovine FSH) when tested in the lizard Anolis carolinensis. 2. 2. Steroidogenic processes (androgen production) in the lizard testis is less temperature sensitive than is spermatogenesis. 3. 3. The temperature dependence of the lizard's response to gonadotropins is evidently a characteristic of the reptile's gonadal system rather than a property of the hormone's structure.

Rates of disappearance from blood and biological potencies of mammalian gonadotropins (HCG and ovine LH) in the toad Bufo bufo bufo (L.)

In hypophysectomized toads Bufo bufo bufo (L.), daily subcutaneous injections of human chorionic gonadotropin (HCG) effectively stimulate vitellogenic growth of oocytes whereas ovine luteinizing hormone (LH) is almost inactive. This difference in potency of the two chemically closely related hormones is correlated with the rates at which the hormones disappear from the blood. In hypophysectomized toads the circulatory half-life of ovine LH was about 40 min. Injected HCG disappcared at decreasing rates, from half-lives of about 3 hr to about 30 hr. It is suggested that the different potency of HCG and LH in stimulating vitellogencsis in hypophysectomized female toads can be due to the different length of time hormone is available to the organism, rather than to different affinities of the ovarian receptors toward the two hormones.

Comparative activities of mammalian, reptilian, and piscine gonadotropins in monkey granulosa cell cultures

Gonadotropic preparations from the pituitaries of a reptile (snapping turtle, Chelydra serpentina) and a teleost fish (Chinook salmon, Oncorhynchus tshawytscha) were examined for biological activity in cultures of granulosa cells obtained from pregnant mare's serum gonadotropin-treated rhesus monkeys. Turtle gonadotropin that was inactive in several of the standard in vivo mammalian assays for gonadotropins clearly brought about morphological luteinization and stimulated progestin secretion in the primate granulosa cell cultures. A 10 μg/ml dose of the turtle gonadotropin consistently brought about a 20–50-fold stimulation and a 1 μg/ml dose brought about a 1–3-fold stimulation in progestin secretion compared to control cultures after a 12-day culture period. Thus, contrary to earlier findings, the reptilian hormone has the requisite structure for recognition by mammalian gonadotropin receptors and demonstrates a lack of zoological specificity in its actions. In contrast, the piscine gonadotropin preparation was inactive at doses between 1 and 100 μg/ml in monkey granulosa cell cultures sensitive to 0.1 μg NIH-FSH-S1 or less than 0.01 μg NIH-LH-S1. Thus, the potency of this preparation was less than 0.0001 × NIH-LH-S1 or 0.001 × NIH-FSH-S1. In view of its potency in other assay systems (piscine, reptilian, and avian), the salmon gonadotropin demonstrated a marked specificity in its action with regard to the mammalian receptors.

Elevation of plasma gonadotropin concentration in response to mammalian gonadotropin releasing hormone (GRH) treatment of the male brown trout as determined by radioimmunoassay.

Rapid increase of the plasma gonadotropin concentration as measured by radioimmunoassay has been demonstrated in response to GRH treatment of the sexually mature male brown trout. Peak gonadotropin values were observed within 15 minutes of GRH treatment, however, the return to baseline values was prolonged compared with the mammalian response. These data support the concept that the brain, operating via releasing hormones, plays a role in the control of pituitary hormone secretion in fish.

Effects of pituitary hormones, melatonin, and thyroidal inhibitors on radioiodide uptake by the thyroid glands of larval and adult tiger salamanders, Ambystoma tigrinum (Amphibia: Caudata)

Thyroidal uptake of radioiodide 24 hr after intraperitoneal injection of 131I was used as a measure of thyroidal function in the tiger salamander ( Ambystoma tigrinum). Larvae pretreated for 7 days with 2.5 or 25 μg TSH/day exhibited significantly greater 131I uptake than did untreated animals. Spontaneously metamorphosing animals accumulated 131I equivalent to larvae pretreated with 2.5 μg TSH. Fully metamorphosed animals were insensitive to pretreatment with 2.5 μg TSH/day, but did respond to 25 μg TSH/day. PTU or SCN pretreatment of larvae reduced TSH-stimulated 131I uptake to control levels, but prolactin, melatonin, and bovine pineal extract had no effect. Prolactin treatment of larvae (7 or 60 days) did not influence 131I uptake as compared to controls. Thyroidal 131I uptake in metamorphosed animals was not influenced by 7 days of treatment with prolactin. Daily pretreatment (7 days) with 25 μg LH or FSH or 0.25 μg TSH did not increase 131I accumulation by larvae. Mammalian prolactin and gonadotropins apparently are not heterothyrotropic factors in this species. The stimulation of metamorphosis by mammalian gonadotropins (Norris et al., 1973b) can be attributed to the amount of mammalian TSH present in these preparations.

The effect of exogenous hormone treatment on spermiation and vitellogenesis in the grey mullet, Mugil cephalus L.

The effects of mammalian gonadotropins, methyltestosterone and partially purified salmon gonadotropin on spermiation and oocyte maturation were studied in adult grey mullet. Methyltestosterone was a potent spermiating agent in both prespawning and spawning trials. The most effective dose was 5 mg/100 g body weight. Human chorionic gonadotropin (HCG) was moderately effective at a dose rate of 20 IU/100 g body weight. Both hormones blocked resorption of milt in captive animals. The HCG, FSH/LH combination, Synahorin+mullet pituitary homogenate, and partially purified salmon gonadotropin were equally effective, at the doses used, in inducing oocyte maturation and preventing onset of atrophy before completion of vitellogenesis. Atrophy occurred in all experimental fish at mean oocyte diameter of 750 μ. The significance of this finding is discussed. (Oceanic Institute Contribution No. 98).

Differential effects of ovine LH and human chorionic gonadotropin on testicular interstitial cells of the lizard Leiolopisma laterale

Male Leiolopisma laterale were treated with 1.0 IU of either LH, HCG, FSH, FSH plus LH or PMSG at a season when the testicular interstitial cells are sparse and the epididymides and renal sexual segment quiescent. All of these mammalian gonadotropins, with the notable exception of LH, increased interstitial cell number, stimulated interstitial cell hypertrophy and cytoplasmic granulation, and increased epididymidal and sexual segment epithelial height. The differential effects of HCG and LH are discussed.

Relative potencies of purified mammalian gonadotropins on the uptake of radiophosphorus by chick testes

Tests with highly purified ovine FSH and LH confirm that the assay based on the uptake of 32P by the testes of day-old chicks does not discriminate between these two hormones. The two gonadotropins are approximately equipotent, and little, if any, synergism is evident between them. The relative potency of highly purified LH(2.7 × NIH-LH-S16) in the chick is in excellent agreement with potency estimates for the same preparation in mammalian bioassay. However, the relative potency of purified FSH in the chick (11 × NIH-FSH-S9) is only about 20% that observed in mammalian bioassay.

A vista of research on the mammalian gonadotropins. Carl G. Hartman Lecture.

A vista of research on the mammalian gonadotropins. Carl G. Hartman Lecture.

Cross-reaction in a chicken LH radioimmunoassay with plasma and pituitary extracts from various species

A radioimmunoassay for chicken luteinizing hormone (LH) was used to investigate possible cross-reactions with plasmas and pituitary extracts from a range of vertebrates. Dose-response curves parallel with that for chicken LH were found with the ten bird species tested and with pituitary extracts from three reptiles. Mammalian gonadotrophins showed little or no cross-reaction in the assay. Results with lower vertebrate material were more varied. The results are discussed in terms of the usefulness of the assay in avian reproductive endocrinology.

The influence of ovine follicle stimulating hormone (FSH) and luteinizing hormone (LH) on the male reproductive system and the skin of the Mediterranean blenniid fish Blennius sphinx (Valenciennes).

AbstractThe Mediterranean Blenniid fish Blennius sphinx has a unique male reproductive system: the testes lie close to voluminous lipid bodies through which the sperm must pass. The tubules, through which the sperm travel, lead to a collection duct opening ventrally into locally enlarged sperm ducts. These taper off caudally and join in an unpaired terminal section which opens into a genital papilla. Slightly posterior to the union, the duct forms two blind pouches extending laterally to the caudal third of the testes. In addition, during spawning, Blennius sphinx shows a glandular system of unknown function in the first and second spines of the anal fin.In this paper, the reactions of the sex‐linked structures described above, and of the mucous cells in the epidermis of post‐spawning fishes, to injections of mammalian FSH and LH are studied. By LH‐treatment the proportion of the animals with fully active testes is increased from 36% (controls) to 83%. The height of the lipid body is increased about 26% by LH‐injections, as compared with the controls. This effect is correlated with an increase in the size of the lipid vacuoles of about 28%. In the epithelium of the paired portions of the sperm duct, LH promotes the formation of aldehyde fuchsin‐positive granules in the cells. The proportion of this type of secretion rises from 18% (controls) to 68% after LH‐treatment. In the terminal unpaired part of the sperm duct, within the genital papilla, the epithelium is thickened by about 38% by this hormone. Injections of LH decrease the height of the blind pouch epithelium, which is well developed, and actively secreting in most of the controls. They also suppress secretion and vascularisation in this structure. LH promotes the formation of the anal gland system, increasing the proportion of the animals with maximally developed glandular systems from 0% (untreated controls) or about 17% (H2O‐treated controls) to 91%. This effect is correlated with an increase of the diameter of the single glands of about 40%. This is also the case in FSH‐treated fishes (23%). The number of the mucous cells in the epidermis decreases by 46% and 45% after FSH‐ and LH‐treatment, respectively. In no case were the effects strictly correlated with the hormone dose. The problems of the action of mammalian gonadotrophins, especially FSH, in fishes; the possible functions of the organs associated with the male genital tract of Bl. Sphinx, and the possible role of the mucous cells in the osmoregulation of fishes are discussed.

The Control of the Reptilian Gonad

In reptiles, there is adequate evidence to indicate environmental control of the ovarian cycle through hvpothalamic pathways and the subsequent release of tropic hormone (s) from the anterior pituitary. The role of the pineal-parietal complex still remains to be elucidated. In the hypothalamus there appear to be steroid sensitive areas and both progesterone and estrogen appear to have important feedback influences upon gonadal growth ovulation, and ovarian steroid production. Cytological studies of the reptilian pituitary indicate similar cell types to those observed in mammalian pituitaries, but thus far, two gonadotrophs cannot be identified with any certainty. Chemical and biological studies of the action of mammalian gonadotropuis suggest that in reptiles hormones which are FSH-like in mammals are able to stimulate gonadal development, ovulation, and steroid biosynthesis under certain conditions. Preliminary studies of the chemistry of turtle gonadotropuis have so far demonstrated only one active principle, which is chemically similar to mammalian LH, but is far more active than the latter hormone in reptilian systems. Further, the hormone also has FSH-like activity in the reptile. Thus reptilian gonadal development can be stimulated by treatment with a variety of mammalian gonadotropins. Recent studies have indicited an important role for growth hormone, acting in concert with gonadotropin and estrogen in the regulation of vitellogenesis and ovarian growth. Piolactin appears to be an antigonadal agent in reptiles, as does progesterone. The exact manner in which these hormones exert their antigonadal action remains to be clarified, but at least one site of action is the central nervous system; other sites maybe the liver and the fat depot. Ovarian tissue from reptiles is able to synthesize and secrete steioid hormones by pathways similar to those present in mammalian ovaries. Circulating levels of estrogen have not been measured, but progesterone levels in the blood show distinct changes assocnted with pregnancy and the presence of corpora lutea in the ovary.

Effects of piscine and mammalian gonadotropins on gametogenesis in the catfish, Heteropneustes fossilis (bloch)

Salmon (SG-G100) and mammalian (ovine FSH and LH) gonadotropins were tested for their gonadotropic activity in the hypophysectomized catfish, Heteropmeustes fossilis, by evaluating induction of spermatogenesis and spermiation in the male, as well as vitellogenesis, ovarian maintenance, and ovulation in the female. In the male, SG-G100 was 10 times more potent than LH in reinitiating and restoring spermatogenesis; FSH was virtually ineffective, even at high dose levels. Spermiation was induced only by SG-G100. Vitellogenesis was induced by SG-G100 and carp pituitary Sephadex G100 fraction II, whereas LH and carp pituitary Sephadex G100 fractions I and III were inefective at comparable dose levels. SG-G100 was 5 and 2.5 times more potent than LH in ovarian maintenance and ovulation responses, respectively; FSH was only marginally effective even at high dose levels. Our data provide corroborative evidence for the tentative view that, in teleosts, only a single gonadotropin (physiologically similar to mammalian LH) may regulate the whole maturational phenomenon.