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See detailChanges in Serum Concentrations of Steroids During Embryonic and Post-Hatching Development of Male and Female Japanese Quail (Coturnix Coturnix Japonica)
Schumacher, M.; Sulon, Joseph ULg; Balthazart, Jacques ULg

in Journal of Endocrinology (1988), 118(1), 127-34

Serum concentrations of testosterone, 5 alpha-dihydrotestosterone, oestradiol and progesterone were measured by radioimmunoassay combined with Celite chromatography in male and female Japanese quail ... [more ▼]

Serum concentrations of testosterone, 5 alpha-dihydrotestosterone, oestradiol and progesterone were measured by radioimmunoassay combined with Celite chromatography in male and female Japanese quail (Coturnix coturnix japonica) during the second half of embryonic life (days 9-17 of incubation) and during the first 5 weeks after hatching. The mean level of each of the four steroids was significantly affected by the age of the birds. An overall effect of sex was detected by analysis of variance only on oestradiol concentrations, with females having higher serum concentrations than males during most of the age range studied. Significant peaks of testosterone and progesterone were also detected around hatching time. These results are consistent with the view that oestradiol is the major hormone implicated in the sexual differentiation of reproductive behaviour in the quail. The relationships between the circulating concentrations of oestradiol during ontogeny and the critical period of differentiation as postulated by currently accepted models is also discussed. [less ▲]

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See detailNeuroanatomical Distribution of Testosterone-Metabolizing Enzymes in the Japanese Quail
Schumacher, M.; Balthazart, Jacques ULg

in Brain Research (1987), 422(1), 137-48

We describe a very sensitive and precise assay which allows one to study the metabolism of testosterone (T) in small brain nuclei dissected out according to the method of Palkovits and Brownstein. With ... [more ▼]

We describe a very sensitive and precise assay which allows one to study the metabolism of testosterone (T) in small brain nuclei dissected out according to the method of Palkovits and Brownstein. With this method, the neuroanatomical distributions of aromatase, and 5 alpha- and 5 beta-reductase activities were studied in adult male quail (Coturnix coturnix japonica). The different enzymes show different neuroanatomical distributions. Production of estradiol-17 beta (E2) was highest in the sexually dimorphic nucleus preopticus medialis (POM). We showed previously that the preoptic aromatase activity is higher in male than in female quail. As the POM is a central and very large structure within the preoptic area, the present results suggest a relationship between the neuroanatomical and the biochemical sex differences. By contrast, the production of 5 alpha-DHT was highest in the lateral hypothalamic area (LHY), the bed nucleus of the pallial commissure (BPC) and the lateral septum (SL). The 5 beta-reductase activity was highest in the lateral septum and in the ventral part of the archistriatum (AV). Moreover, there was a rostral to caudal decrease in 5 beta-reductase activity in the hypothalamus. [less ▲]

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See detailCentral and Peripheral Metabolism of 5 Alpha-Dihydrotestosterone in the Male Japanese Quail: Biochemical Characterization and Relationship with Reproductive Behavior
Deviche, P.; Delville, Y.; Balthazart, Jacques ULg

in Brain Research (1987), 421(1-2), 105-16

An in vitro radioenzymatic assay and purification procedure by thin-layer chromatography were used to study the metabolism of dihydrotestosterone (DHT) into 3 alpha- and 3 beta-androstanediols by the ... [more ▼]

An in vitro radioenzymatic assay and purification procedure by thin-layer chromatography were used to study the metabolism of dihydrotestosterone (DHT) into 3 alpha- and 3 beta-androstanediols by the brain and cloacal gland of Japanese quail. Kinetic studies showed that these 2 metabolites are produced in a linear fashion with respect to time of incubation for up to 15 min but that they continue to accumulate for up to 4 h. The maximum velocity of these reactions is high (nmol/mg protein/15 min), but the affinities of the enzymes for DHT are low (in the microM range). The enzymatic activities are not evenly distributed in the brain: they are high in the tuberal hypothalamus and lobus parolfactorius but low in the preoptic area and anterior hypothalamus. Enzyme activities are not markedly affected by treatment of the birds with either testosterone or DHT. The activity of these enzymes is lower in the preoptic area and tuberal hypothalamus of DHT-treated birds which display female-directed sexual behavior than in the same brain areas of birds which are sexually inactive. We discuss the relationships between this reductive metabolism of DHT and the activational effects of the steroid on sexual behavior. [less ▲]

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See detailSteroid Hormones, Behavior and Sexual Dimorphism in Animals and Men: The Nature-Nurture Controversy
Schumacher, M.; Legros, Jean-Jacques ULg; Balthazart, Jacques ULg

in Experimental & Clinical Endocrinology (1987), 90(2), 129-56

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See detailHormonal Control of Female Sexual Behavior in the Japanese Quail
Delville, Y.; Balthazart, Jacques ULg

in Hormones & Behavior (1987), 21(3), 288-309

Four experiments were carried out to study the hormonal control of female receptivity and proceptivity in Japanese quail. Both aspects of reproductive behavior can be activated in a dose-dependent manner ... [more ▼]

Four experiments were carried out to study the hormonal control of female receptivity and proceptivity in Japanese quail. Both aspects of reproductive behavior can be activated in a dose-dependent manner by injections of estradiol benzoate (EB). Progesterone (P) given in addition to suboptimal doses of EB has little additional stimulatory effect. Other aspects of the reproductive physiology such as enlargement of the cloacal diameter and growth of the oviduct also seem to be controlled primarily by estrogens with little or no additive effect of P. These conclusions were confirmed by injecting egg-laying females with an antiestrogen, tamoxifen, or an antiprogestin, RU38486. Only the former had marked effects on sexual receptivity, cloacal diameter, and oviduct weight. The inhibiting effects of tamoxifen could easily be reversed by injecting females with large doses of estrogen, which demonstrates that tamoxifen acts on an estrogen-dependent mechanism and not through nonspecific effects. [less ▲]

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See detailEffect of the injection solvent on steroid activity.
Deviche, P.; Balthazart, Jacques ULg

in General and Comparative Endocrinology (1987), 65(2), 199-202

The effects of testosterone, 5 alpha-dihydrotestosterone, and androstenedione on cloacal gland and sternotracheal muscle growth and on luteinizing hormone plasma levels were studied in Japanese quail. The ... [more ▼]

The effects of testosterone, 5 alpha-dihydrotestosterone, and androstenedione on cloacal gland and sternotracheal muscle growth and on luteinizing hormone plasma levels were studied in Japanese quail. The steroids were given to the animals in daily intramuscular injections and were dissolved either in propylene glycol or in ethanol:saline (1:1). The three steroids had significant effects on the responses which were measured, but the magnitude of this effect was clearly related to the type of vehicle in which the steroids were dissolved. Furthermore there was a significant interaction between the effects of solvents and of steroid; for example, testosterone was much less androgenic than 5 alpha-dihydrotestosterone when dissolved in propylene glycol, but both had similar effects when dissolved in ethanol:saline. The effects of the mode of administration of different steroids on a given physiological response should be taken into consideration. [less ▲]

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See detailInteractions des androgenes et des oestrogenes dans le controle de la reproduction
Schumacher, M.; Alexandre, Corine; Balthazart, Jacques ULg

in Comptes Rendus de l'Académie des Sciences. Série III, Sciences de la Vie (1987), 305(14), 569-74

Castrated male quail were injected with the synthetic oestrogen, diethylstylbestrol (DES) or the synthetic androgen, methyltrienolone (R 1881) or both compounds simultaneously. Both R 1881 and DES ... [more ▼]

Castrated male quail were injected with the synthetic oestrogen, diethylstylbestrol (DES) or the synthetic androgen, methyltrienolone (R 1881) or both compounds simultaneously. Both R 1881 and DES activated male sexual behaviour, inhibited LH and FSH secretion and increased hypothalamic aromatase activity. Additive effects between R 1881 and DES were observed for the induction of brain aromatase and for the inhibition of FSH secretion. As a consequence, mechanisms mediated by androgen and estrogen receptors must be involved in the control of these reproductive characteristics. [less ▲]

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See detailInhibition of testosterone metabolism in the brain and cloacal gland of the quail by specific inhibitors and antihormones.
Alexandre, Corine; Balthazart, Jacques ULg

in Journal of Endocrinology (1987), 112(2), 189-95

The effects of antioestrogens, antiandrogens and of various inhibitors of testosterone metabolism on testosterone metabolism in the quail hypothalamus and cloacal gland were studied by an in-vitro ... [more ▼]

The effects of antioestrogens, antiandrogens and of various inhibitors of testosterone metabolism on testosterone metabolism in the quail hypothalamus and cloacal gland were studied by an in-vitro radioenzymatic assay. It was found that antioestrogens and antiandrogens generally had little or no effect on aromatase and 5 alpha- and 5 beta-reductases of testosterone, except when used at very high doses. The 5 alpha-reductase inhibitor, 17 beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5 alpha-androstan-3-one, inhibited both 5 alpha- and 5 beta-dihydrotestosterone production without markedly affecting aromatase activity. Surprisingly, the aromatase inhibitor, 1,4,6-androstatriene-3,17-dione, inhibited not only the production of oestradiol but also that of 5 beta-dihydrotestosterone and, to a lesser extent, 5 alpha-dihydrotestosterone. These unexpected properties should be taken into account when interpreting the results of in-vivo experiments using these compounds. [less ▲]

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See detailSexual differentiation and hormonal control of the sexually dimorphic medial preoptic nucleus in the quail.
Panzica, G. C.; Viglietti-Panzica, C.; Calacagni, M. et al

in Brain Research (1987), 416(1), 59-68

We recently identified a sexually dimorphic nucleus in the preoptic region of the Japanese quail, the medial preoptic nucleus (POM), which is significantly larger in males than in females. In the present ... [more ▼]

We recently identified a sexually dimorphic nucleus in the preoptic region of the Japanese quail, the medial preoptic nucleus (POM), which is significantly larger in males than in females. In the present study, we investigated the hormonal control of this morphological neuroanatomical difference and the possible relationships between the sexual dimorphism in POM volume and in copulatory behavior. Treatments which are known to affect sexual behavior were thus applied to different groups of birds and the POM volume was then measured. In one experiment, male and female quails were either gonadectomized, gonadectomized and treated with testosterone or left intact. The larger size of the POM in males was confirmed and treatments significantly affected the nucleus size which was decreased by gonadectomy and restored by testosterone treatment in both sexes to a level similar to that seen in intact males. In two other experiments, eggs were injected with estradiol benzoate on day 9 of incubation and the POM volume was measured in adulthood either in intact birds or in gonadectomized birds receiving a replacement therapy with testosterone. Despite the fact that estradiol benzoate treatment completely suppressed copulatory behavior, it did not affect the volume of the POM or slightly increased it. These data thus show that the POM volume is controlled by testosterone levels in adulthood and could thus be an interesting model for the study of the effects of steroids on the brain. [less ▲]

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See detailSeasonal changes in some plasma hormones in pigeons: diurnal variation under natural photoperiods with constant or seasonally changing ambient temperature.
Rintamaki, H.; Hissa, R.; Etches, R. J. et al

in Comparative Biochemistry and Physiology (1986), 84(1), 33-8

The diurnal variations of several plasma hormones and free fatty acids (FFA) were studied during periods in summer and winter for pigeons reared either outdoors or indoors. The latter were subjected to ... [more ▼]

The diurnal variations of several plasma hormones and free fatty acids (FFA) were studied during periods in summer and winter for pigeons reared either outdoors or indoors. The latter were subjected to constant temperature and naturally varying photoperiods. A significant seasonal variation in the mean daily levels of triiodothyronine (T3), thyroxine (T4), corticosterone (B), lutropin (LH) and FFA was seen in the outdoor birds and in the T4 and B levels of indoor birds. The diurnal variation of hormone levels was generally more pronounced in winter in both groups. Cold ambient temperature significantly decreased the plasma LH level and potentiated the increasing effect of short photoperiod on plasma B level. Diurnal variation of plasma FFA level seems to be under the control of photoperiod, without any effects due to the ambient temperature. No significant correlation was found between FFA and GH concentrations. [less ▲]

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See detailSeasonal changes in some plasma hormones in pigeons from different environments.
Saarela, S.; Hissa, R.; Etches, R. et al

in Comparative Biochemistry and Physiology (1986), 84(1), 25-31

Seasonal variation in the plasma concentration of lutropin (LH), follitropin (FSH), prolactin (PRL), thyroxine (T4), triiodothyronine (T3) and corticosterone (B) were measured in the pigeon by RIA methods ... [more ▼]

Seasonal variation in the plasma concentration of lutropin (LH), follitropin (FSH), prolactin (PRL), thyroxine (T4), triiodothyronine (T3) and corticosterone (B) were measured in the pigeon by RIA methods. Pigeons were maintained indoors under constant ambient temperature (Ta) and simulated natural daylight (LD), 12:12 L:D regimens or outdoors exposed to seasonal variations in temperature and photoperiod at Oulu, Finland. Only slight changes of gonadotropins (LH, FSH) were observed throughout the year, without any clear photosensitive or photorefractory period. In the indoor (natural LD) group, LH stayed elevated from May until October. Interdependence between the circannual hormonal fluctuation and photoperiod could not be shown, although the amplitude of FSH, T4 and T3 fluctuation of pigeons maintained in laboratory conditions were greater than that of natural LD and outdoor pigeons, whose circannual rhythms were similar. A high concentration of plasma PRL in autumn and the peak value of B in winter for all groups are thought to be correlated to lipid metabolism. Two peaks, the first in winter and the second in autumn, observed in T4 and T3 hormone profiles, may be due to molting of the pigeons. [less ▲]

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See detailA two-step model for sexual differentiation.
Balthazart, Jacques ULg; Schumacher, M.

in Annals of the New York Academy of Sciences (1986), 474

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See detailA sexually dimorphic nucleus in the quail preoptic area.
Viglietti-Panzica, C.; Panzica, G. C.; Fiori, M. G. et al

in Neuroscience Letters (1986), 64(2), 129-34

The cytoarchitectural analysis of the preoptic-anterior hypothalamic region of the Japanese quail reveals a sexual dimorphism in the total volume of the medial preoptic nucleus (significantly larger in ... [more ▼]

The cytoarchitectural analysis of the preoptic-anterior hypothalamic region of the Japanese quail reveals a sexual dimorphism in the total volume of the medial preoptic nucleus (significantly larger in males than in females). Different nuclei of the region (dorsal preopticus, suprachiasmaticus) do not show any statistically significant difference. The sex-related difference is more consistent comparing the distribution of dark volume. This last is due to a larger number of cells containing high amount of Nissl's substance in male than in female. Present findings represent the first example of sexual dimorphism in the avian hypothalamus. [less ▲]

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See detailAltered endocrine and behavioral responses with reproductive aging in the male Japanese quail.
Ottinger, M. A.; Balthazart, Jacques ULg

in Hormones and Behavior (1986), 20(1), 83-94

Experiments were conducted to further characterize the age-related decline in reproductive capability previously described in the male Japanese quail. Behavioral testing of a large number of males in ... [more ▼]

Experiments were conducted to further characterize the age-related decline in reproductive capability previously described in the male Japanese quail. Behavioral testing of a large number of males in several age groups confirmed earlier results that showed a significant reduction in courtship and mating behavior by 80 weeks of age. Intact males, 78 weeks of age, that showed no reproductive behavior were given Silastic implants containing testosterone. This treatment restored behavior in 80% of the males. Gonadal regression induced by exposure to shortened photoperiod followed by transfer to a stimulatory photoperiod did not successfully restore the endocrine or behavioral components of reproduction. Males of two age groups, 42 and 208 weeks of age, were categorized as behaviorally active or inactive and then castrated. Eight weeks later they were given implants containing testosterone. Older males required longer exposure time to the exogenous steroid and in some cases, an additional implant to restore mating behavior as compared to younger males. The presence or absence of behavioral activity prior to castration did not affect the length of time required for restoration of behavior. Challenge with exogenous luteinizing hormone-releasing hormone revealed that there was reduced release of luteinizing hormone in aged, behaviorally inactive males as compared to young males. Results of these experiments in addition to previous data give evidence that age-related changes occur at the level of the hypothalamus and pituitary as well as at the level of the gonads. [less ▲]

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See detailDiurnal variations of sexual receptivity in the female Japanese quail (Coturnix coturnix japonica).
Delville, Y.; Sulon, J.; Balthazart, Jacques ULg

in Hormones and Behavior (1986), 20(1), 13-33

A series of experiments was performed to study the changes during the day of female receptivity in Japanese quail. In each experiment, the frequency of squatting and the percentage of male approaches ... [more ▼]

A series of experiments was performed to study the changes during the day of female receptivity in Japanese quail. In each experiment, the frequency of squatting and the percentage of male approaches which were followed by squatting increased at the end of the day, approximately 11 to 13 hr after lights on (in a photoperiod of 16L:8D). In some cases this increased receptivity was associated with a significant decrease of the long-avoid frequency. Analyses are presented which demonstrate that the increased receptivity at the end of the day is not directly caused by the oviposition and does not result directly from changes in the behavior of the male stimuli. This is strongly supported by the observation that the increase in receptivity was observed at the same time after lights on (but different clock times) in two groups of females which were raised in two different photoperiods shifted by 6 hr and tested with the same group of males raised in one of the two photoperiods. The increase in receptivity coincides with an increase in plasma estradiol and progesterone. Considering that this behavior is suppressed by ovariectomy, it is argued that the daily changes in receptivity could be controlled by the hormonal changes associated with the ovulatory cycle. [less ▲]

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See detailTestosterone-induced brain aromatase is sexually dimorphic.
Schumacher, M.; Balthazart, Jacques ULg

in Brain Research (1986), 370(2), 285-93

Female quail are less sensitive than males to the activating effects of testosterone (T) on behavior. Testosterone induces hypothalamic aromatase activity more efficiently in males than in females (higher ... [more ▼]

Female quail are less sensitive than males to the activating effects of testosterone (T) on behavior. Testosterone induces hypothalamic aromatase activity more efficiently in males than in females (higher Vmax but similar Km). As the conversion of T to estradiol (E2) is important for the activation of male sexual behavior, we propose that the incapacity of the female hypothalamus to produce behaviorally active E2 contributes to their insensitivity to T. The 5 alpha-reductase, which converts T into 5 alpha-dihydrotestosterone (5 alpha-DHT), is induced by T specifically in the anterior hypothalamus of both sexes. [less ▲]

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See detailComparison of monoamine concentrations in the brains of adult male and female Japanese quail.
Ottinger, M. A.; Schumacher, M.; Clarke, R. N. et al

in Poultry Science (1986), 65(7), 1413-20

A fluorometric assay measuring brain tissue concentrations of norepinephrine, dopamine, and serotonin has been validated for Japanese quail. Accuracy, precision, specificity, and parallelism were ... [more ▼]

A fluorometric assay measuring brain tissue concentrations of norepinephrine, dopamine, and serotonin has been validated for Japanese quail. Accuracy, precision, specificity, and parallelism were determined. The sensitivity of the assays was 6 ng/tube, which allowed individual assay of 1 to 2 mg hypothalamic tissue. In Experiment 1, relatively large areas of brain from adult, reproductively active males and females were found to differ significantly in norepinephrine content in optic lobes and for dopamine in right telencephalon. A microdissection technique was used in Experiment 2 to sample small portions of hypothalamic tissue. Sex differences were observed for norepinephrine in the sections containing the lobus paraolfactorius and the preoptic, anterior, and medial hypothalamus. Differences in monoamine content were most apparent when smaller areas dissected by microdissection were analyzed. These results give evidence for sex differences in the monoamine content in specific areas of the brain. [less ▲]

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See detailEffects of metabolism inhibitors, antiestrogens and antiandrogens on the androgen and estrogen induced sexual behavior in Japanese quail.
Alexandre, Corine; Balthazart, Jacques ULg

in Physiology & Behavior (1986), 38(4), 581-91

The relative contribution of androgenic and estrogenic metabolites of testosterone to the activation of sexual behavior was studied in Japanese quail by using inhibitors of testosterone metabolism ... [more ▼]

The relative contribution of androgenic and estrogenic metabolites of testosterone to the activation of sexual behavior was studied in Japanese quail by using inhibitors of testosterone metabolism, antiestrogens and antiandrogens. These compounds were tested in castrated birds whose sexual behavior had been activated by silastic implants of testosterone (T) or daily injections of testosterone propionate (TP) or diethylstilboestrol (DES). The aromatase inhibitor ATD only depressed T-induced behavior when injected at high doses and the 5 alpha-reductase inhibitor, 4MA was inactive in this respect. The antiestrogens, tamoxifen (TAM) and nitromifene citrate (CI-628) strongly depressed sexual behavior but they also drastically reduced the crowing behavior which is typically androgen-dependent which throws some doubts on the specificity of their action. The antiandrogens, flutamide and cyproterone acetate (CA), only had limited inhibitory effects on the copulatory behavior but similarly decreased only marginally the crowing. As they strongly depressed the cloacal gland growth, it can be ascertained that they were injected in sufficient amounts and their lack of action on crowing questions the ability of these compounds to inhibit brain processes even when they are androgen-dependent. Taken together with the results of previous experiments which tested the behavioral effects of the testosterone metabolites, the present data confirm the implication of both androgenic and estrogenic metabolites of testosterone in the activation of behavior. Their interaction remains, however, poorly defined and its understanding will probably require the identification of the biochemical processes which in the brain mediate the behavior. [less ▲]

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See detailBrain testosterone metabolism during ontogeny in the zebra finch.
Balthazart, Jacques ULg; Schumacher, M.; Prove, E.

in Brain Research (1986), 378(2), 240-50

The testosterone metabolism in different parts of the brain and in the syrinx was studied by an in vitro radioenzyme assay in male and female zebra finch (Taeniopygia guttata castanotis) at various ages ... [more ▼]

The testosterone metabolism in different parts of the brain and in the syrinx was studied by an in vitro radioenzyme assay in male and female zebra finch (Taeniopygia guttata castanotis) at various ages between 1 day post-hatch and adulthood. The 5 beta-reductase appeared in all experiments as the main enzyme involved in testosterone metabolism. Two experiments allowed to determine the kinetic parameters of the 5 beta-reductase. It was shown that the Vmax of the 5 beta-reduction is much higher in very young animals than in adults but that the Km of the enzyme is smaller (higher affinity) in the latter than in the former. A major decrease of 5 beta-reductase activity is observed during the ontogeny of both males and females in all the tissue samples which were studied including the hypothalamus and brain regions containing nuclei of the song system. This high reductase activity which produces behaviorally inactive compounds is likely to play a protective role during the sexual differentiation of the birds and in this way prevent the masculinization in females of the song system by the relatively high levels of circulating androgens. [less ▲]

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See detailHormonal correlates of gonadal regression and spontaneous recovery in Japanese quail exposed to short day-lengths.
Delville, Y.; Sulon, J.; Balthazart, Jacques ULg

in Archives Internationales de Physiologie et de Biochimie (1985), 93(2), 123-33

Adult male Japanese quail were transferred from long to short days. Plasma testosterone and dihydrotestosterone quickly decreased and this endocrine response was followed by a regression of the cloacal ... [more ▼]

Adult male Japanese quail were transferred from long to short days. Plasma testosterone and dihydrotestosterone quickly decreased and this endocrine response was followed by a regression of the cloacal gland, an androgen-target organ. After about a month, a spontaneous recovery of gonadal activity was observed in some but not all birds. It was not associated with obvious shifts in the circadian system. The physiological bases of this spontaneous recovery are discussed as well as the detailed relationships between plasma testosterone and cloacal gland size. [less ▲]

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