Male Gonadal Hormones Research Articles

Development of the anal fin appendicular support in the western mosquitofish, Gambusia affinis affinis (Baird and Girard, 1854): a reinvestigation and reinterpretation.

Development of the sexually dimorphic anal fin appendicular support of an internal fertilizing bony fish Gambusia affinis affinis was investigated by staining whole-mounted embryos, immature, and adult female and male G. a. affinis with alizarin red S and alcian blue. The tissue was examined histologically to assess development of the amphicelous centrum and to verify specificity of the stains. Our data confirm earlier claims about the development of the male and female characteristics in this species, and we provide for the first time direct embryonic evidence suggesting that development of the sexually dimorphic anal fin appendicular support is biphasic: (1) anteriorization of the most anterior caudal segments, and (2) growth and elongation of hemal arches of vertebrae 14-16. The first process involves a sequential homeotic transformation of hemal arches of vertebrae 11-13 through resorption of mineralized connective tissue, thus forming parapophyses that bear pleural ribs. This process begins in undifferentiated embryos and proceeds similarly in postnatal males and females. During the same period, the second process, likely induced by male gonadal hormones, causes the addition of mineralized connective tissue at the hemal arches of vertebrae 14-16. This second process, which occurs only in males, elongates the hemal arches of vertebrae 14-16 anteriorly. This elongation apparently translocates the anal fin appendicular support (including parts of the hemal spine of the hemal arch of vertebra 13) to the level of vertebra 11. It appears that the developmental programs of both female and male G. a. affinis create an area of 6 vertebrae which are markedly different from any vertebrae anterior to 11 and posterior to 16. We propose to term the area including these vertebrae and the associated anal fin, the genital area. We also propose that the first process, homeotic transformation of caudal into precaudal segments, is regulated by differential expression of control genes, such as homeobox genes, whereas the second process is regulated by gene expression under the control of male gonadal hormones. Conflicting data in the literature can be resolved with this model. Appropriate tests of the model are proposed.

Circulating gonadal steroid hormones regulate estrogen receptor mRNA in the male rat forebrain

In male rats, the conversion of testosterone to estrogen via aromatization is a critical step in a number of androgen-mediated functions, especially reproductive behavior. Within the central nervous system (CNS), locally formed estrogen binds to its cognate estrogen receptor protein. Little is known about what factors regulate the expression of estrogen receptors in the male rat CNS. This study examined whether circulating male gonadal steroid hormones have a role in the regulation of estrogen receptor mRNA in brain regions critical for the expression of male reproductive behavior. Male rats were gonadectomized or sham operated, and 3 days later were sacrificed. Their brains were fixed by perfusion, frozen, and sectioned. Tissue sections were hybridized to an 35S-labeled 850 base cDNA probe, complementary primarily to the steroid binding domain of the estrogen receptor mRNA. Following post-hybridization washes, slides were dipped in photographic emulsion and exposed for 2 weeks. Estrogen receptor mRNA-containing neurons were observed in all brain regions previously shown by steroid hormone autoradiography to concentrate estrogen. Gonadectomy did not alter the number of estrogen receptor mRNA-producing neurons, but did produce a two-fold increase in the relative amount of estrogen receptor mRNA per cell in the medial preoptic nucleus, periventricular preoptic area, and bed nucleus of the stria terminalis. This study shows that circulating gonadal steroids down-regulate steady state levels of estrogen receptor mRNA within specific brain regions, and thereby have the potential to regulate the sensitivity of particular target regions in the CNS to estrogen.

Oxytocin, a male intragonadal hormone.

It is now well recognised that oxytocin is not confined to the hypothalamo-neurohypophysial system but present elsewhere in the body. However, the significance of the peptide in these peripheral sites is still unclear. This paper considers the evidence for oxytocin to be a male gonadal hormone and focusses on three of the criteria which need to be fulfilled for it to earn this title: oxytocin must be produced within the gonads; have a physiological action and be regulated by factors which alter gonadal function.

The same myosin isoforms are found in the female and male sexually dimorphic levator ani muscle of the rat, but their postnatal transitions are not synchronous

The levator ani of the female adult rat is greatly atrophied in comparison to the same muscle in males. In the present study, the female levator ani was, nevertheless, found to contain type IIb myosin isoforms similar to those contained in the male muscle. These adult type isoforms were, however, synthesized later in the female than in the male levator ani: the half-transition times of the myosin transition curve were 20 days postnatal in the male and 35 days postnatal in the female. The transition curves for castrated and uncastrated male rats were the same. Thus, the presence of male gonadal hormones apparently did not affect the myosin transition.

Influence of male gonadal hormones and familiarity on pregnancy interruption in prairie voles.

Pregnancy interruption (PI) was examined in female prairie voles, Microtus ochrogaster, exposed to stimuli from males 7 to 12 days after pairing. Urine from unfamiliar males interrupted pregnancy when placed directly on the external nares of newly mated females, but urine from familiar stud males was without effect. Castration of males did not reduce the efficacy of unfamiliar male urine in interrupting pregnancy. The neuroendocrine system of female prairie voles responded selectively to male urine as a function of its familiarity; the efficacy of male stimuli leading to PI was not dependent on gonadal hormones.

Gender differences in two forms of cold-water swim analgesia

Female rats display lower shock thresholds and less morphine analgesia than male rats, differences which are sensitive to gonadal manipulations. Baseline pain thresholds and morphine analgesia also vary across the estrous cycle of female rats. The first experiment demonstrated that 'nonopioid' continuous cold-water swim (CCWS: 2 degrees C for 3.5 min) analgesia and 'opioid' intermittent cold-water swim (ICWS: 2 degrees C, 18 10-sec swims and 10-sec rests over 3 min) analgesia are subject to gender-specific effects. The magnitudes of CCWS and ICWS analgesia were significantly lower in female rats as compared to either age-matched or weight-matched male rats. The jump test displayed a more consistent pattern than the tail-flick test. The second experiment failed to show differences in the magnitude of CCWS analgesia across the female estrous cycle. These data demonstrate that both opioid (ICWS) and nonopioid (CCWS) forms of stress-induced analgesia are sensitive to gender differences, and suggest that male gonadal hormones may enhance analgesic responsivity.

Play soliciting behavior in prepubertal and postpubertal male rats

Pre- and postpubertal play soliciting behavior was observed in intact males, castrate males, sham-operated males, and female controls. Although play soliciting decreased markedly with age in all groups, male treatment groups did not differ reliably on pre- or postpubertal tests. Males, however, engaged in reliably greater play soliciting than females on all measures in both preand postpubertal tests. These results suggest that the major decrease in social play associated with the attainment of sexual maturity is apparent in the play soliciting behavior of both sexes and may be attributed to maturation effects other than that associated with gonadal hormones. The results are discussed in reference to organizational and activational effects of male gonadal hormones on measures of social play behavior.

Sex-dependent endorphinergic and adrenergic control mechanisms of luteinizing hormone secretion in immature rats.

Previous studies in male and female immature rats have revealed striking sex differences as concerns endorphinergic and adrenergic control of luteinizing hormone (LH) secretion. The present study examines in 10 days old male and females rats whether these differences result from sexual differentiation of the brain, or acute effects of male and female gonadal hormones. The techniques employed to manipulate these mechanisms were gonadectomy immediately post-partum and androgenization. Androgenization on the 1st and 2nd day of life reduces the ability of naloxone to elevate serum LH levels in females, but failed to modify the LH-elevating effect of clonidine in males. Experiments with castrates showed that testosterone is critical for these sex-related differences. Treatment with testosterone on the 9th day of life of intact or gonadectomized rats revealed the ability of this hormone to modify LH-release acutely. We conclude that sexual differentiation of the brain may be of minor significance for the sex-related LH-control mechanisms in prepubertal rats. Of importance is the acute presence of testosterone, since in its absence male characteristics disappear.

Effect of castration and subsequent substitution with testosterone, dihydrotestosterone and oestradiol on sexual preference behaviour in the male rat

In the present study effects of castration and subsequent hormonal substitution on the partner-preference behaviour of the male rat are investigated. For the determination of this behaviour a residential plus-maze is used. Castration of a male rat leads to the disappearance of preference behaviour after a few weeks. Subsequent administration of testosterone by means of a silastic implant restores this behaviour within a few weeks. Castrated male rats with a silastic implant containing dihydrotestosterone will not seek contact with the oestrous female rat. Oestradiol-implanted castrated male rats show the same behaviour in the residential plus-maze as do intact male rats. It is concluded that in the male rat gonadal hormones have an effect on the processing of the signals which an oestrous female rat emits to attract a male.

Chemosensory and hormonal mediation of social memory in male rats.

The persistence with which adult male rats investigated a juvenile conspecific was significantly reduced following preexposure to either the juvenile or chemosensory stimuli (soiled bedding or urine) from that juvenile. The reduced persistence did not occur when the chemosensory stimulus came from a juvenile different from the one with which the subject was subsequently tested, which suggests the presence of a chemosensorily mediated social memory. It is suggested that any such memory may have adaptive value in that it permits a male rat to more readily identify a novel conspecific. Also, the lack of reduced persistence of social investigatory behavior in castrated subjects demonstrates the importance of male gonadal hormones in the formation, storage, and/or retrieval of the proposed chemosensorily mediated social memory.

Gonadectomy attenuates turning behavior produced by electrical stimulation of the nigrostriatal dopamine system in female but not male rats

Rotational behavior induced by electrical stimulation of ascending dopamine neurons is used as a behavioral model to investigate gender and hormonal influences on extra-hypothalamic dopamine systems. Steroid hormones influence the metabolism of many dopaminergic drugs, and therefore this approach avoids the complications inherent in drug-induced behavior models of dopamine activity. We found that gonadectomy of female, but not male, rats severely attenuates electrical stimulation-induced rotational behavior. This suggests that some female gonadal steroid hormone(s) may modulate the activity of ascending dopamine neurons, while male gonadal hormones do not.

Androgen effects on responsiveness to aggression and stress-related odors of male mice

The effect of male gonadal hormones on responsiveness to the aggression and stress-related odors of male mice was examined. The initial experiment indicated that intact male mice would avoid an area of an open field that had been spotted with the urine of aggressive male donors, while castration of the subjects eliminated the response. Hormone replacement was effective in reinstating the aversion, clearly demonstrating the androgen-dependent nature of the response. A second experiment determined that the effects of castration do not generalize to another type of aversive odor, namely the alarm odors of castrate donors. That is, both intact and castrate males exhibited a pronounced aversion to the urine odors of castrates that had been subjected to a prolonged period of stress. These results suggest that gonadal hormone effects on olfactory responsivity are somewhat specific, and more interestingly, that the mechanism behind the effects of gonadal hormones on rodent aggression may lie in their influence on the nature of the response to the relevant olfactory stimuli.

Influence of gonadal hormones and social housing conditions on agonistic, copulatory, and related socio-sexual behaviour in the Mongolian gerbil ( Meriones unguiculatus)

The Mongolian gerbil is colonial, but its social organization within its colonies is not known. Pair formation has been suggested by breeders and has been observed under semi-natural conditions. Family units remain stable under such conditions. In the solitary-living hamster ( Cricetus auratus), agonistic behaviour decreases in male-female encounters during female heat. This report concerns the influence of female and male gonadal hormones on agonistic behaviour in gerbils studied in cagemate and non-cagemate encounters. Further, the occurrence of mating, marking, and drumming was studied in the same situations. No effects were found of either the female or the male endocrine condition on the low amount of agonistic behaviour between cagemates. A reduction in the high amount of agonistic responses in encounters between non-cagemates was indicated. It was related to the castrated-male and induced-oestrous female conditions. Copulatory behaviour was not influenced by social maintenance conditions. Marking and drumming were most frequent in females in oestrous and intact males. The occurences in the females were influenced by the individual's endocrine condition, but not by the opponent's. Intact males in encounters with non-cagemates marked more frequently when the females were in anoestrous. Drumming in the intact males increased in tests with oestrous versus anoestrous females but occurred more frequently in encounters with non-cagemates than in those with cagemates. The behaviour of castrated males was not influenced by the endocrine or by social housing conditions. The limited variation in agonistic behaviour relative to the endocrine conditions may reflect a non-solitary social organization.

The role of neonatal androgen in the expression of hormonally induced maternal responsiveness in the adult rat

The role of neonatal androgen in the expression of hormonally induced maternal responsiveness in rats was investigated. Four to six hours postnatally male rats were either castrated or sham-castrated, while females were injected with testosterone propionate or oil, or were noninjected controls. When 90 days old the subjects were assigned either to a 21-day maternal hormone or to a vehicle regimen. Following these adult treatments subjects were tested for maternal responsiveness by means of a retrieving test in the home cage and in a T-maze. In the home cage test the adult hormone treatment caused a significant reduction in the time to sensitization in all neonatal treatment groups. In the T-maze only subjects with no androgen postnatally and with hormones in adulthood retrieved significantly more than their adult vehicle controls. It was concluded that the development of the potential to respond fully to the hormonal changes of pregnancy is inhibited by the postnatal presence of the male gonadal hormone.

Sexual dimorphism in the primary immune response of the Syrian hamster.

The primary immune response patterns of young adult male and female hamsters injected with SRBC cells were studied and compared. The females were shown to produce higher numbers of PFC per spleen than did males. Similar results were obtained using aged males and females. These results were found to be independent of circadian rhythm for the males tested. Effects of pre- and post-pubertal gonadectomy on the primary immune response suggest that female advantage in terms of specific immunoglobulin synthesis depends primarily on the relative absence of male gonadal hormones.

Inhibition of pituitary gonadotrophic activity in the viviparous seaperch Cymatogaster aggregata Gibbons by a dithiocarbamoylhydrazine derivative (I.C.I. 33 828).

A suspension of Methallibure (I.C.I. Compound 33 828) was added regularly for about 6 weeks to aquaria housing males of the teleost Cymatogaster aggregata. The testis atrophied and the gametogenetic processes of maturation were suspended. Histochemically demonstrable 3β-hydroxysteroid dehydrogenase and sudanophilic lipids diminished and the interstitial cells of Leydig regressed. At the end of the experiments the fleshy modifications on the male anal fin (secondary sex structures which develop under the influence of male gonadal hormones) were in a state characteristic of immature fish. Methallibure treatment resulted in these changes, which were characteristic of hypophysectomy, without the marked antithyroid activity histologically evident in thiourea treatment. All thiourea-treated and control animals remained in breeding condition. It is concluded that the addition of Methallibure to the aquarium water will directly block the production and (or) release of pituitary gonadotropins and thus inhibit spermatogenesis and testicular steroidogenesis.

Inhibition of the pituitary gonadotropic activity of fishes by a dithiocarbamoylhydrazine derivative (I.C.I. 33,828)

Three teleost fishes, Carassius auratus, Gasterosteus aculeatus, and Cymatogaster aggregatus, have been injected for periods of about 4 weeks with a suspension of Methallibure (I.C.I. Compound 33,828). Although division of the primary germ cells continued, the gametogenetic processes of maturation were suspended in the gonads of both sexes of all three species. The brush border segments of the kidney tubules of Gasterosteus, a secondary sex character which increase in thickness under the influence of male gonadal hormones, remained in a state characteristic of immature fish; control animals showed changes characteristic of the breeding season. It is concluded that this compound blocks the action of pituitary gonadotropins on both the gametogenetic and the endocrine tissues of the testis.

Development of Nippostrongylus brasiliensis in gonadectomized and hormone-treated hamsters

Gonadectomy of male hamsters from 2 weeks to 1 day (27–30 hours) prior to infection was followed by a significant decrease in the recovery of adult worms, whereas gonadectomy during the infection period had no apparent effect on adult worm burdens. Gonadectomy before infection did not increase the adult worm burdens of female hamsters. Testosterone propionate injections in doses of 5, 10, or 20 mg shortly before infection reversed the effects of gonadectomy in mature male hamsters; recoveries of adult worms varied with the dose. Testosterone injections also increased the susceptibility of normal male and gonadectomized and normal female hamsters. Preliminary studies indicated that progesterone was as effective as testosterone in increasing the susceptibility of normal female hamsters, whereas estradiol benzoate, cholesterol, and cortisone had no effect on adult worm burdens under the conditions studied. The effect of gonadectomy on the migration of larvae from the site of intracutaneous inoculation to the lungs and intestines generally supported the findings of the studies on adult worms, although it was found that the necropsy time selected was of importance. Significantly fewer larvae were recovered from the lungs of gonadectomized males than from those of sham controls at 15, 27, and 39 hours after infection; however, there was no significant difference in larval recoveries from the lungs of gonadectomized and sham-operated animals at 3, 6, and 9 days. After injections of testosterone at 16 and 8 hours prior to infection, larvae arrived more rapidly in the lungs of gonadectomized males and normal females than in those of the sesame oil controls, and considerable numbers reached the intestines by the third day of infection. The present findings strongly suggest that male gonadal hormones can act to condition the integument of the hamster, thereby facilitating the penetration and migration of Nippostrongylus brasiliensis larvae. Removal of the gonads from the male would remove the major source of androgens and permit changes in the integumentary structures (i.e., ground substances) sufficient to slow down initially the migration of larvae; injections of testosterone into the male or female would put the animal into a relatively highly susceptible state. The importance of the lung barrier in the gonadectomized host was also considered in relation to timing mechanisms and internal secretions. Whether testosterone can act directly on the worms or indirectly while the worms are still in the lungs is not yet known.

Influences of the gonad on the thymus in the mouse

In mice of an inbred Japanese dd-strain, age changes in the thymus weight were studied for both sexes from 5 days until 300 days of age. Further studies were made on effects of gonadectomy on the thymus in both male and female mice which were gonadectomized at 35 days and 100 days of age. 1. The thymus grows markedly at the same rate in both sexes in early life until at about 35 days it reaches a maximum in weight. Then it decreases in weight due to age involution. During adolescence and early maturity until about 100 days the decrease in thymus weight is relatively rapid, and it is more prominent in males than in females. During sexual maturity after 120 days until 300 days so far examined, the decrease in the thymus weight is very slow, and the thymus is significantly heavier in females than in males. 2. The sex difference in the thymus weight is no longer evident in gonadectomized mice. The thymus of the male responds to castration by a remarkable increase in weight, while the thymus of the female is little influenced by ovariectomy. From these considerations it is surmised that the sex difference in the thymus weight is due to that the thymus in the male is suppressed by the testis, namely, the male gonadal hormone.

Hormones and Secondary Sex Characters in the Minnow, Hyborhynchus

Previous articleNext article No AccessHormones and Secondary Sex Characters in the Minnow, HyborhynchusL. S. Ramaswami and Arthur D. HaslerL. S. Ramaswami Search for more articles by this author and Arthur D. Hasler Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 28, Number 1Jan., 1955 Article DOIhttps://doi.org/10.1086/physzool.28.1.30152180 Views: 2Total views on this site Citations: 12Citations are reported from Crossref Journal History This article was published in Physiological Zoology (1928-1998), which is continued by Physiological and Biochemical Zoology (1999-present). Copyright 1955 The University of ChicagoPDF download Crossref reports the following articles citing this article:Matthew B. Dugas, Nathan R. Franssen, Maya O. Bastille, Ryan A. Martin Morphological correlates of river velocity and reproductive development in an ornamented stream fish, Evolutionary Ecology 30, no.11 (Aug 2015): 21–33.https://doi.org/10.1007/s10682-015-9790-7Stephanie C. McMillan, Zhe T. Xu, Jing Zhang, Cathleen Teh, Vladimir Korzh, Vance L. Trudeau, Marie-Andrée Akimenko Regeneration of breeding tubercles on zebrafish pectoral fins requires androgens and two waves of revascularization, Development 140, no.2121 (Nov 2013): 4323–4334.https://doi.org/10.1242/dev.095992L. M. Unger, R. C. Sargent Allopaternal care in the fathead minnow, Pimephales promelas: females prefer males with eggs, Behavioral Ecology and Sociobiology 23, no.11 (Jul 1988): 27–32.https://doi.org/10.1007/BF00303054David O. Norris Regulation of Male Gonaducts and Sex Accessory Structures, (Jan 1987): 327–354.https://doi.org/10.1007/978-1-4613-1869-9_11Lawrence M. Unger Nest defense by deceit in the fathead minnow, Pimephales promelas, Behavioral Ecology and Sociobiology 13, no.22 (Aug 1983): 125–130.https://doi.org/10.1007/BF00293802N.R. Liley, N.E. Stacey 1 Hormones, Pheromones, and Reproductive Behavior in Fish, (Jan 1983): 1–63.https://doi.org/10.1016/S1546-5098(08)60301-5D. Sasse, W. Pfeiffer, M. Arnold Epidermale Organe am Kopf von Morulius chrysophakedion (Cyprinidae, Ostariophysi, Pisces), Zeitschrift f�r Zellforschung und Mikroskopische Anatomie 103, no.22 (Jan 1970): 218–231.https://doi.org/10.1007/BF00337313S. K. Nayyar, Bangalore I. Sundararaj Response of the seminal vesicles of the hypophysectomized catfish Heteropneustes fossilis (Bloch) to exogenous androgens, estrogen and corticosteroid+, Journal of Fish Biology 2, no.11 (Jan 1970): 69–78.https://doi.org/10.1111/j.1095-8649.1970.tb03260.xH. Gottfried The occurrence and biological significance of steroids in lower vertebrates. A review, Steroids 3, no.22 (Feb 1964): 219–242.https://doi.org/10.1016/0039-128X(64)90080-7G.J. VAN OORDT Male Gonadal Hormones, (Jan 1963): 154–207.https://doi.org/10.1016/B978-0-12-395549-4.50010-7William S. Hoar Hormones and the reproductive behaviour of the male three-spined stickleback (Gasterosteus aculeatus), Animal Behaviour 10, no.3-43-4 (Jul 1962): 247–266.https://doi.org/10.1016/0003-3472(62)90049-0L.S. Ramaswami Endocrinology of reproduction in fish and frog, General and Comparative Endocrinology 1 (Jan 1962): 286–299.https://doi.org/10.1016/0016-6480(62)90099-0