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See detailEffects of Alpha-Methyl-Para-Tyrosine on Monoamine Levels in the Japanese Quail: Sex Differences and Testosterone Effects
Balthazart, Jacques ULg; Foidart, Agnès ULg; Sante, P. et al

in Brain Research Bulletin (1992), 28(2), 275-88

Experiments were performed to obtain more information on the regulation by steroids of catecholaminergic systems in the brain of Japanese quail. Dose-response and time-response experiments were first ... [more ▼]

Experiments were performed to obtain more information on the regulation by steroids of catecholaminergic systems in the brain of Japanese quail. Dose-response and time-response experiments were first performed to determine optimal conditions for measuring turnover in the quail brain. The norepinephrine and dopamine turnover were then estimated in microdissected brain nuclei of birds that were either sexually mature or gonadectomized or gonadectomized and treated with testosterone. Two major facts that bear direct relationship with the control of masculine reproductive behavior were demonstrated. On one hand, the dopamine turnover in the medial preoptic nucleus, a sexually dimorphic brain structure which is critically implicated in the control of copulatory behavior was much higher in male than in female quail irrespective of the hormonal condition of the birds. On the other hand, norepinephrine concentrations appeared to be higher in several nuclei of the female brain by comparison with males. These sex differences might represent part of the causal factors that underlie the sex dimorphism in reproductive behavior in quail. [less ▲]

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See detailThe Induction by Testosterone of Aromatase Activity in the Preoptic Area and Activation of Copulatory Behavior
Balthazart, Jacques ULg; Foidart, Agnès ULg; Hendrick, J. C.

in Physiology & Behavior (1990), 47(1), 83-94

A series of 4 experiments was designed to study the relationships between the activity of the aromatase (AA) in the preoptic area (POA) and the activation by testosterone (T) of copulatory behavior in ... [more ▼]

A series of 4 experiments was designed to study the relationships between the activity of the aromatase (AA) in the preoptic area (POA) and the activation by testosterone (T) of copulatory behavior in gonadectomized male and female Japanese quail. The induction of AA by T in the POA is dose- and time-dependent. Levels of AA seen in sexually mature males are restored in castrated birds by a treatment with 20 to 40 mm silastic T capsules which produce physiological levels of steroid in the plasma. The minimal dose of T (10 mm implant) which reliably restores copulatory behavior approximately doubles the AA in the POA. The induction of AA is significantly larger in males than in females. A significant increase in AA is observed within 16 hours after the start of the treatment with T and the induction is maximal after 48 hours. Activation of copulatory behavior follows a similar time course but occurs with a delay of 24-48 hours. These results thus suggest that, in male quail, the activity of the aromatase in the POA is a limiting factor in the activation of copulatory behavior. This idea is confirmed by direct experimentation using an aromatase inhibitor, androstatrienedione (ATD). If T-treated birds receive at the same time silastic implants filled with ATD, the activation of behavior is suppressed for at least one week. This behavioral inhibition is, as expected, accompanied and very probably caused by the inhibition of the aromatase activity in the preoptic area and anterior hypothalamus. No increase of enzyme activity over the level seen in castrates was actually detected during the first 8 days of exposure to T. A moderate increase in AA was seen on day 16 and is probably responsible for the behavioral activation which was observed at the end of the experiment. [less ▲]

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See detailEssais de localisation des RNA polymérases dans des cellules tumorales d'Ehrlich par immunocytochimie ultrastructurale
Thiry, Marc ULg; Hendrick, J C; Lepoint, Alain et al

in Biology of the Cell (1986), 57

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See detailEtude immunocytochimique ultrastructurale de cellules tumorales d'Ehrlich à l'aide d'anticorps dirigés contre la RNA polymérase d'E. Coli
Thiry, Marc ULg; Hendrick, J C; Lepoint, Alain et al

in Bulletin de l'Association des Anatomistes (1986), 70

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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 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 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 detailEndocrine effects of castration followed by androgen replacement and ACTH injections in the male domestic duck (Anas platyrhynchos L.).
Deviche, P.; Balthazart, Jacques ULg; Heyns, W. et al

in General and Comparative Endocrinology (1980), 41(1), 53-61

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See detailEffects of exogenous gonadotropic and steroid hormones on the social behaviour and gonadal maturation of male domestic ducklings Anas platyrhynchos L.
Balthazart, Jacques ULg; Hendrick, J. C.

in Archives Internationales de Physiologie et de Biochimie (1979), 87(4), 741-61

Male domestic ducklings were injected during their first month of life with mammalian gonadotrophins (ovine LH or FSH, HMG) or gonadal steroids (testosterone or oestradiol). LH and testosterone stimulated ... [more ▼]

Male domestic ducklings were injected during their first month of life with mammalian gonadotrophins (ovine LH or FSH, HMG) or gonadal steroids (testosterone or oestradiol). LH and testosterone stimulated sexual behaviour while oestradiol inhibited the increase of aggression observed in control birds during the experiment. The mammalian gonadotrophins did not increase plasma testosterone but nevertheless they all stimulated the testis growth. Several hypotheses which could explain this finding (stimulation of spermatogenesis without any apparent effect on testosterone) are discussed and the possibility of a direct action of LH on the sexual behaviour is analysed. Social displays were only moderately stimulated by testosterone and not at all by gonadotrophins. The hormonal controls of these behaviour patterns remains thus largely unknown. [less ▲]

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See detailSteroidal control of plasma luteiyizing hormone, comb growth and sexual behaviour in male chicks.
Balthazart, Jacques ULg; Hendrick, J. C.

in Journal of Endocrinology (1978), 77(1), 149-50

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See detailControle hormonal du comportement et de la croissance testiculaire chez la caille coturnix corturnix japonica
Balthazart, Jacques ULg; Hendrick, J. C.

in Comptes Rendus Biologies (1977), 171(3), 656-63

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See detailDiurnal variations of plasma gonadotrophins in male domestic ducks during the sexual cycle.
Balthazart, Jacques ULg; Hendrick, J. C.; Deviche, P.

in General and Comparative Endocrinology (1977), 32(4), 376-89

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See detailDosage radioimmunologique de l'hormone folliculo-stimulante (FSH) hypophysaire de canard a l'aide d'un systeme de mammiferes
Croix, D.; Hendrick, J. C.; Balthazart, Jacques ULg et al

in Comptes Rendus des Séances de la Société de Biologie et de ses Filiales (1974), 168(1), 136-40

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