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See detailInteraction of androgens and estrogens in the control of sexual behavior in male Japanese quail.
Balthazart, Jacques ULg; Schumacher, M.; Malacarne, G.

in Physiology & Behavior (1985), 35(2), 157-66

A series of 4 experiments was performed to study the relative contribution of androgens and estrogens in the activation of sexual behavior in castrated male quail. The synthetic androgen methyltrienolone ... [more ▼]

A series of 4 experiments was performed to study the relative contribution of androgens and estrogens in the activation of sexual behavior in castrated male quail. The synthetic androgen methyltrienolone (R 1881) which is not metabolized in androgen target tissues activated sexual behavior in castrated birds and at the dose level of 0.5-1 mg/day/animal had the same potency as testosterone (T). However R 1881 was much more active than T in the induction of cloacal gland growth and activation of crowing, two typically androgen-dependent responses. This suggests that sexual behavior is not controlled by exactly the same mechanism as crowing or cloacal gland growth. In another experiment, estradiol (E2) alone activated sexual behavior but it is only at very high doses which had clear toxic effects that a significant behavioral activation could be observed. This questions the role of E2 as the physiological agent stimulating copulation in intact birds unless it is assumed that centrally administered E2 would be much more active compared to peripheral E2 which is exposed to a very intense peripheral catabolism. In the last two experiments, a clear synergism could be detected between 5 alpha-dihydrotestosterone (5 alpha-DHT) and E2 in the activation of sexual activity and doses of hormones could be defined which had almost no activity by themselves but significantly stimulated sexual behavior when given simultaneously. It was however impossible to define a hormonal treatment with T metabolites which restored behavior to its precastration level, a result very easily achieved with T treatments. Taken together, these data suggest that activation of sexual behavior in quail does not depend only on E2, nor 5 alpha-DHT nor even on their combined action. Considering that specific T receptors which probably do not bind 5 alpha-DHT are present in the brain, it would seem justified to reconsider the possible role played by T itself in the activation of behavior. [less ▲]

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See detailThe effect of pinealectomy on plasma levels of gonadotrophins and growth hormone in the pigeon (Columba livia).
Rintamaki, H.; Hissa, R.; Balthazart, Jacques ULg et al

in Journal of Pineal Research (1984), 1(4), 381-9

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See detailSexual dimorphism in the hypothalamic metabolism of testosterone in the Japanese Quail (Coturnix coturnix japonica).
Schumacher, M.; Balthazart, Jacques ULg

in Progress in Brain Research (1984), 61

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See detailChanges in testosterone metabolism by the brain and cloacal gland during sexual maturation in the Japanese quail (Coturnix coturnix japonica).
Balthazart, Jacques ULg; Schumacher, M.

in Journal of Endocrinology (1984), 100(1), 13-8

Testosterone metabolism in the brain and pituitary and cloacal glands of male and female Japanese quail was studied in vitro during sexual maturation (from 1 day to 5 weeks after hatching). The production ... [more ▼]

Testosterone metabolism in the brain and pituitary and cloacal glands of male and female Japanese quail was studied in vitro during sexual maturation (from 1 day to 5 weeks after hatching). The production of 5 alpha-dihydrotestosterone in the hyperstriatum and cloacal gland and that of androstenedione in the cloacal gland of males was highest at 1 day after hatching, which could be related to the peak of plasma androgens previously demonstrated in neonatal quail. 5 beta-Reductase activity was very high in the brain, but not the pituitary or cloacal glands of young chicks and decreased markedly, especially in the hypothalamus, during sexual maturation. As 5 beta-reduced metabolites of testosterone are inactive androgens, it is suggested that the decrease of 5 beta-reductase activity with age corresponds to a potentiation of the effects of testosterone at the level of the brain. [less ▲]

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See detailRelative potencies of testosterone and 5 alpha-dihydrotestosterone on crowing and cloacal gland growth in the Japanese quail (Coturnix coturnix japonica).
Balthazart, Jacques ULg; Schumacher, M.; Malacarne, G.

in Journal of Endocrinology (1984), 100(1), 19-23

It has been suggested that testosterone is less effective at inducing crowing behaviour in young birds than in adults because of the presence of higher levels of steroid 5 beta-reductase in the young ... [more ▼]

It has been suggested that testosterone is less effective at inducing crowing behaviour in young birds than in adults because of the presence of higher levels of steroid 5 beta-reductase in the young brain, which converts testosterone to inactive 5 beta-reduced metabolites. This hypothesis was tested indirectly by comparing the relative potencies of 5 alpha-dihydrotestosterone (5 alpha-DHT), which cannot be converted to 5 beta-metabolites, and testosterone at inducing crowing in young gonadectomized male and female quail. The promotion of cloacal gland growth by these treatments was also assessed since there are no age-related changes in 5 beta-reductase in this organ. Silicone elastomer implants (2 X 5, 5 and 10 mm) containing 5 alpha-DHT were more effective at stimulating crowing than similar implants of testosterone whilst there was little difference in their potency at inducing cloacal gland growth. These results are consistent with the hypothesis that brain steroid 5 beta-reductase regulates the behavioural activity of testosterone in the brain of young birds. [less ▲]

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See detailPartial characterization of testosterone-metabolizing enzymes in the quail brain.
Schumacher, M.; Contenti, E.; Balthazart, Jacques ULg

in Brain Research (1984), 305(1), 51-9

The properties of 5 beta-reductase, 5 alpha-reductase and aromatase, 3 testosterone metabolizing enzymes, were studied in the quail brain by an in vitro incubation technique. The results describe the ... [more ▼]

The properties of 5 beta-reductase, 5 alpha-reductase and aromatase, 3 testosterone metabolizing enzymes, were studied in the quail brain by an in vitro incubation technique. The results describe the changes in time of metabolite production and the effects of temperature, enzyme and cofactor concentrations. The apparent Km and Vmax were evaluated for the 3 enzymes. Aromatase and 5 alpha-reductase have a higher affinity but a lower capacity than 5 beta-reductase. The kinetics of the latter enzyme are complex and suggest the presence of two types of enzymes. These characteristics fit in well with the role probably played by the enzymes in vivo. [less ▲]

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See detailEffect of the presence of females on the pituitary-testicular activity in male Japanese quail (Coturnix coturnix japonica).
Delville, Y.; Sulon, J.; Hendrick, J. C. et al

in General and Comparative Endocrinology (1984), 55(2), 295-305

Five experiments were carried out to study the role of the presence of a female on the reproductive endocrinology of male Japanese quail. In the first three experiments, exposure of an adult male raised ... [more ▼]

Five experiments were carried out to study the role of the presence of a female on the reproductive endocrinology of male Japanese quail. In the first three experiments, exposure of an adult male raised in long days to a female for l0 min or l week failed to increase plasma testosterone and LH levels; in fact a significant transitory decrease in plasma testosterone was observed, associated with a preceding increase in plasma corticosterone. These changes are interpreted as a result of the stress caused by repeated bleeding or by the continuous presence of a female in a limited space. In the last two experiments, an increase in the maturation rate of immature males could be observed in birds maintained in the continuous presence of females by comparison with birds kept in isolation. The paired males had larger cloacal glands and testes and higher plasma levels of testosterone and LH than the isolated one. This effect of the female was observed in long days (l6L:8D) as well as in marginally stimulating short days (l2L:l2D). [less ▲]

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See detailAltered brain metabolism of testosterone is correlated with reproductive decline in aging quail.
Balthazart, Jacques ULg; Turek, R.; Ottinger, M. A.

in Hormones and Behavior (1984), 18(3), 330-45

In aging quail, an increasing proportion of males show no sexual behavior. A decrease in the mean size of the tests, cloacal gland, and sternotracheal muscles is also observed. In both sexually active and ... [more ▼]

In aging quail, an increasing proportion of males show no sexual behavior. A decrease in the mean size of the tests, cloacal gland, and sternotracheal muscles is also observed. In both sexually active and inactive males, plasma testosterone decreases with age but more so in inactive birds. The behavioral and morphological changes observed during aging are correlated with shifts in the intracellular testosterone metabolism resulting in a change in the ratio of active versus inactive metabolites. In the hypothalamus there is a steady decrease with age of 5 beta-reductase activity in all birds and an increase in 5 alpha-reductase activity only in the birds which remain sexually active. In the cloacal gland, the 5 beta-reductase activity markedly increases with age but more so in the birds which become sexually inactive. These data support the notion that the effects of testosterone are controlled by enzymatic shifts which could modulate the sensitivity to the hormone at the cellular level. [less ▲]

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See detailOrganization and activation of behavior in quail: role of testosterone metabolism.
Balthazart, Jacques ULg; Schumacher, M.

in Journal of Experimental Zoology (The) (1984), 232(3), 595-604

In quail, the hypothalamus enzymatically transforms testosterone (T) into estradiol (E2), 5 alpha-dihydrotestosterone (5 alpha-DHT), and 5 beta-dihydrotestosterone (5 beta-DHT). During the embryonic life ... [more ▼]

In quail, the hypothalamus enzymatically transforms testosterone (T) into estradiol (E2), 5 alpha-dihydrotestosterone (5 alpha-DHT), and 5 beta-dihydrotestosterone (5 beta-DHT). During the embryonic life, the 5 beta-reductase activity is very high, which probably protects the brain of males from being behaviorally demasculinized by their endogenous T. 5 beta androstanes are inactive androgens. The decrease of 5 beta reductase with age during sexual maturation corresponds to a potentiation of the effects of T as shown by experiments that compared the effects of T and 5 alpha-DHT in adult and young quail. T metabolism is also involved in the activation of male behavior in the adult. T aromatization is probably essential for behavioral activation, but nonaromatizable androgens such as methyltrienolone, and to some extent 5 alpha-DHT, can also stimulate sexual behavior in castrates. These enzymatic activities show a clear neuroanatomical localization and are sexually dimorphic. Males produce more active metabolites (E2, 5 alpha-DHT) than females, which could explain the male's greater sensitivity to T treatments. It thus appears that T metabolism is involved in the differentiation and activation of behavior in quail. [less ▲]

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See detailThe postnatal demasculinization of sexual behavior in the Japanese quail (Coturnix coturnix japonica).
Schumacher, M.; Balthazart, Jacques ULg

in Hormones and Behavior (1984), 18(3), 298-312

Three experiments were performed to analyze the time course of demasculinization in the Japanese quail and to test the activating and organizing effects of estradiol (E2) in adult sexually active birds ... [more ▼]

Three experiments were performed to analyze the time course of demasculinization in the Japanese quail and to test the activating and organizing effects of estradiol (E2) in adult sexually active birds. In Experiment 1, males and females were castrated at the age of 1 day or 1, 2, 4, and 6 weeks and treated as adults with testosterone (T). The age of castration had no effect on behavior and morphology in males. Plasma gonadotrophins (LH and FSH) were, however, higher in males castrated at or before than in those castrated after 2 weeks of age. This suggests that postnatal testicular secretions have organizing effects on the pituitary activity. Females which were castrated before 1 week of age were less sensitive to the activating effects of T than males, but were not fully demasculinized. The demasculinization of different reproductive characteristics such as male sexual behavior, cloacal gland size, and weight of the syringeal muscles is achieved in females at different times posthatching. In Experiment 2, castration of male and female quail at the ages of 4 days or 4 weeks confirmed that postnatal ovarian secretions contribute to the full behavioral and morphological demasculinization of females. It is easier to elicit mounting in T-treated females when they are tested in their home cage instead of a test arena. This difference was not observed in males. During Experiment 3, it was impossible to demasculinize sexually active adult males or females by treatment with Silastic implants of E2. E2 did not maintain sexual behavior in ovariectomized females showing male sexual behavior when treated with T but maintained the behavior in males. [less ▲]

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See detailEstradiol contributes to the postnatal demasculinization of female Japanese quail (Coturnix coturnix japonica).
Balthazart, Jacques ULg; Schumacher, M.

in Hormones and Behavior (1984), 18(3), 287-97

Two experiments were performed to characterize the process of postnatal demasculinization in Japanese quail. In the first experiment, it was shown that estradiol (E2) can complete female demasculinization ... [more ▼]

Two experiments were performed to characterize the process of postnatal demasculinization in Japanese quail. In the first experiment, it was shown that estradiol (E2) can complete female demasculinization during the first 4 weeks of life. By contrast, E2 did not demasculinize sexual behavior and cloacal gland in neonatally castrated males. Neonatally gonadectomized females preferentially performed mount attempts when tested in their home cage by comparison to a test arena. In Experiment 2, E2 Silastic implants (40-mm) maintained full copulatory behavior in castrated males but not in females. This large dose of E2 did not demasculinize adult sexually active birds (males or females) even if treatment lasted for 1 month. It is concluded that E2 can demasculinize sexual behavior only in females and only if treatment is performed in very young birds. [less ▲]

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See detailTestosterone metabolism and testosterone-dependent characteristics in Japanese quail.
Delville, Y.; Hendrick, J. C.; Sulon, J. et al

in Physiology & Behavior (1984), 33(5), 817-23

In 2 independent experiments, we measured and correlated in maturing male Japanese quail the individual variations in sexual and aggressive behavior, cloacal gland size, testes weight, plasma testosterone ... [more ▼]

In 2 independent experiments, we measured and correlated in maturing male Japanese quail the individual variations in sexual and aggressive behavior, cloacal gland size, testes weight, plasma testosterone concentrations and intracellular testosterone metabolism by hypothalamus and cloacal gland. Cloacal gland area was only weakly related to plasma testosterone levels but was positively correlated with the production of active androgenic metabolites and negatively related to the production of 5 beta-reduced androgens (inactive) in the glandular tissue. Several measures of behavior were correlated with aspects of the testosterone metabolism in the anterior hypothalamus. In both experiments, the behavior of the birds was also strongly correlated with their testes weight and their cloacal gland area but weakly or not at all with their plasma testosterone levels. These studies suggest that testosterone metabolism is involved in the control of hormone action in maturing animals. [less ▲]

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See detailThe effects of testosterone and its metabolites on sexual behavior and morphology in male and female Japanese quail.
Schumacher, M.; Balthazart, Jacques ULg

in Physiology & Behavior (1983), 30(3), 335-9

Adult Japanese quail are sexually dimorphic. Even when implanted with testosterone (T), ovariectomized females fail to copulate and their cloacal glands are smaller than those of males. This may be due to ... [more ▼]

Adult Japanese quail are sexually dimorphic. Even when implanted with testosterone (T), ovariectomized females fail to copulate and their cloacal glands are smaller than those of males. This may be due to a reduced capacity of the females to transform testosterone into active metabolites (estradiol-17 beta and 5 alpha-dihydrotestosterone). Indeed, in the male quail, estradiol-17 beta (E2) activates copulation whereas 5 alpha-dihydrotestosterone (5 alpha-DHT) activates crowing, strutting and the development of the cloacal gland. To test this hypothesis, we studied the effects of in vivo treatments of male and female quail with the different T-metabolites. Forty-one castrated male and female quail were implanted with subcutaneous silastic implants of T, 5 alpha-DHT, E2 and E2 in combination with 5 alpha-DHT. When implanted with these metabolites, females failed to copulate and their cloacal glands remained less developed than those of males. Sexual differences in behavior and morphology thus cannot be entirely explained by sexual dimorphism of the metabolism. [less ▲]

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See detailAnnual variation in the concentrations of circulating hormones in capercaillie (Tetrao urogallus).
Hissa, R.; Saarela, S.; Balthazart, Jacques ULg et al

in General and Comparative Endocrinology (1983), 51(2), 183-90

Seasonal variation in the levels of immunoreactive lutropin (LH), follitropin (FSH), prolactin (PRL), corticosterone (B), thyroxine (T4), and triiodothyronine (T3) was measured in the plasma of male and ... [more ▼]

Seasonal variation in the levels of immunoreactive lutropin (LH), follitropin (FSH), prolactin (PRL), corticosterone (B), thyroxine (T4), and triiodothyronine (T3) was measured in the plasma of male and female capercaillies (Tetrao urogallus, Galliformes) in captivity (latitude N 67 degrees). In male capercaillies there was an increase in the concentrations of LH and FSH beginning in March and reaching their maxima in May, which correlated with the nesting period. The concentration of plasma PRL increased from the end of April and reached its highest level simultaneously with the rapid fall of plasma LH and FSH concentrations. It remained elevated until August, Plasma T4 level was depressed after levels of plasma FSH and LH had reached their maxima and was correlated to simultaneous elevation of plasma PRL level. No dramatic seasonal changes in plasma T3 level were noted. In the female capercaillie no marked changes in plasma FSH and LH concentrations were observed. Although four of six females laid eggs only one of them managed to terminate its nesting successfully; five eggs hatched. Changes in prolactin concentration in females parallel those in males. No marked variations were observed in plasma corticosterone concentrations. On the basis of these results it seems probable that captive female capercaillie show depressed gonadotrophin secretion, resulting in unsuccessful nesting. On the other hand it has to be emphasized that gonadotrophin assays may not be sensitive enough, especially in the female, to measure LH and FSH in the volumes of plasma put in the assays. [less ▲]

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See detailSexual differences in the Japanese quail: behavior, morphology, and intracellular metabolism of testosterone.
Balthazart, Jacques ULg; Schumacher, M.; Ottinger, M. A.

in General and Comparative Endocrinology (1983), 51(2), 191-207

Three experiments were carried out to study whether differences in the intracellular metabolism of testosterone (T) can explain sexually differential responses to T in Japanese quail. In the first ... [more ▼]

Three experiments were carried out to study whether differences in the intracellular metabolism of testosterone (T) can explain sexually differential responses to T in Japanese quail. In the first experiment, a series of dose-response curves in which length of Silastic testosterone implants was related to effects on several behavioral and physiological variables was established. In Experiment 2, adult males and females were assigned to six experimental groups: intact males and females (I-males and I-females), castrated males and females implanted subcutaneously with 40-mm Silastic implants of T (T-males and T-females), and castrated males and females without hormone treatment (CX-males and CX-females). No CX-bird (male or female) and no I-female exhibited male sexual behavior. However, I-males and T-males regularly copulated during the behavioral tests. No crowing was ever heard in CX-animals and I-females. T-females crowed less than T-males and their crowing sounded weaker than those of males. The cloacal glands of T-females were less developed than those of males. Radioimmunoassay of T and 5 alpha-DHT showed that T-males and T-females have similar plasma levels of androgens. No striking differences were observed in the way testosterone is metabolized by the pituitary gland and central nervous tissues of males and females. By contrast, the production of 5 alpha-dihydrotestosterone (5 alpha-DHT) and 5 alpha-androstane-3 alpha, 17 beta-diol (5 alpha, 3 alpha-diol) was higher in the cloacal glands of males than in those of females. These sex differences were not detected between T-males and T-females. In experiment 3, the cloacal gland of males produced more 5 alpha-reduced metabolites than those of females. The pituitary gland of females also produced more 5 beta-androstane-3 alpha, 17 beta-diol (5 beta, 3 alpha-diol). In syringeal muscles, the production of 5 beta-dihydrotestosterone (5 beta-DHT) and 5 beta, 3 alpha-diol was higher in females compared to males. [less ▲]

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See detailTestosterone metabolism in discrete areas of the hypothalamus and adjacent brain regions of male and female Japanese quail (Coturnix coturnix Japonica).
Schumacher, M.; Contenti, E.; Balthazart, Jacques ULg

in Brain Research (1983), 278(1-2), 337-40

The metabolism of testosterone in small regions of the hypothalamus was studied by an in vitro radioenzymatic assay in male and female Japanese quail. 5 beta-reduction was the most important metabolic ... [more ▼]

The metabolism of testosterone in small regions of the hypothalamus was studied by an in vitro radioenzymatic assay in male and female Japanese quail. 5 beta-reduction was the most important metabolic pathway. This enzymatic activity is not evenly distributed in the brain: it shows a rostral to caudal decrease. There is some suggestion that 5 beta-reduction could be more active in females than in males which could contribute to the behavioral dimorphism in this species. [less ▲]

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See detailThe role of nest-building activity of gonadotrophin secretions and the reproductive success of ring doves (Streptopelia risoria).
Cheng, M. F.; Balthazart, Jacques ULg

in Journal of Comparative and Physiological Psychology (1982), 96(2), 307-24

This study was undertaken to investigate the intricate relations between prelaying nest-building activity and preovulatory hormonal changes, and the effects of these events on breeding success. Pairs of ... [more ▼]

This study was undertaken to investigate the intricate relations between prelaying nest-building activity and preovulatory hormonal changes, and the effects of these events on breeding success. Pairs of ring doves were allowed to go through a complete breeding cycle under four conditions of nest-building opportunity. Nest were self-made, pre-made, pre-made and covered, or removed daily to generate various levels of building activity. Behavioral and hormonal changes were observed throughout the cycle. Blood levels of gonadotrophins were monitored by daily measurements with the method or radioimmunoassay. A depression of follicle-stimulating hormone (FSH) typically was associated with every preovulatory surge of luteinizing hormone (LH); an LH surge not accompanied by a FSH dip was not followed by ovulation. Moreover, the FSH depression was significantly correlated with the level of nest-building activity. These findings led to the proposal that nest-building activity stimulated preovulatory FSH change and, hence, ovulation. The constructed nest in turn appeared to promote incubation behavior. These results are discussed in the context of breeding success. [less ▲]

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See detailEffects of in vivo corticosterone treatment on the in vitro metabolism of testosterone in the comb and brain of the young male chicken.
Deviche, P.; Balthazart, Jacques ULg; Malacarne, G. et al

in General and Comparative Endocrinology (1982), 48(3), 398-402

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See detail5 beta-Dihydrotestosterone is weakly androgenic in the adult Japanese quail (Coturnix coturnix japonica).
Deviche, P.; Bottoni, L.; Balthazart, Jacques ULg

in General and Comparative Endocrinology (1982), 48(4), 421-4

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See detailStimulatory effects of 5 beta-dihydrotestosterone on the sexual behavior in the domestic chick.
Balthazart, Jacques ULg; Malacarne, G.; Deviche, P.

in Hormones and Behavior (1981), 15(3), 246-58

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