Blockade of Testosterone-Induced Mounting Behavior in the Male Rat with Intracranial Application of the Aromatization Inhibitor, Androst-l,4,6-triene-3,17-dione

Christensen, L. W.; Clemens, Lynwood G.

doi:10.1210/endo-97-6-1545

Cited by 163 publications

(50 citation statements)

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“…This result agrees with other studies that directly demonstrated that the conversation of T to E 2 in MPOA of adult male rats is important for activation of male sexual behavior [33, 34]. The finding that E 2 , but not T, stimulated equivalent levels of mounting in males and females suggests that the previously established sexual dimorphism in the capacity for aromatization in the rat brain [8]is functionally related to sex differences in motivational responses to T. These results support the hypothesis that locally formed estrogens contribute to sexual motivation in males.…”

Section: Discussionsupporting

confidence: 93%

Sex Differences in Male-Typical Copulatory Behaviors in Response to Androgen and Estrogen Treatment in Rats

Roselli

Chambers

1999

Neuroendocrinology

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The present experiment was performed to test the hypothesis that gender differences in the capacity for brain estrogen synthesis could constitute a sexually dimorphic mechanism that limits the activational effects of testosterone (T) in females, and enhances them in males. We determined the effects of treatments with equivalent levels of either T or estradiol (E₂) on olfactory behavior and mounting in age-matched heterosexually naive gonadectomized male and female rats that were genitally ansthetized with lidocaine paste in order to minimize the contribution of sexually dimorphic somatosensory inputs to the expression of copulatory behavior. We found that T stimulated mounting to a greater extent in males than in females, but had equivalent effects on mount latency and genital investigation in the two sexes. On the other hand, E₂ stimulated equivalent levels of mounting in males and females and reduced mount latency to a similar extent in males and females. However, E₂ had a pronounced effect on the levels of genital investigation in males but not in females. Serum steroid levels and the levels of nuclear steroid receptor occupation in the brain were not different between males and females, suggesting that the behavioral differences between males and females cannot be attributed to differences in peripheral steroid metabolism or brain uptake. The results obtained corroborate previous studies suggesting that female rats normally undergo considerable male-typical behavioral masculinization during fetal development. However, such male-typical features of normal development in female rats do not extend to the regulation of preoptic aromatase activity or to the capacity of females to display olfactory behaviors in response to adult E₂ exposure, functions which are sexually dimorphic even in the rat. The present results support the view that gender differences in the capacity for brain estrogen synthesis contribute to the sexually dimorphic display of T-stimulated male-typical sexual motivation and copulatory behavior in rats.

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Section: Discussionsupporting

confidence: 93%

Sex Differences in Male-Typical Copulatory Behaviors in Response to Androgen and Estrogen Treatment in Rats

Roselli

Chambers

1999

Neuroendocrinology

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“…However, oestradiol has been demonstrated to mimic the effects of testosterone (Davis & Barfield 1979, Vagell & McGinnis 1997. Furthermore, administration of dihydrotestosterone, a non-aromatizable androgen, was ineffective in restoring male sexual behaviour in castrated rats (McDonald et al 1970) and treatment of neonatal male rats with androst-1,4,6-triene-3,17-dione, an aromatase inhibitor, resulted in modulation of androgen-induced sexual behaviour (Christensen & Clemens 1975, Beyer et al 1976, Booth 1978. These studies proposed a hypothesis that, in rodents, testosterone of testicular origin is aromatized in the brain to oestradiol, which acts as the principle biologically active molecule responsible for brain sexual differentiation at the perinatal stage in the male (Arnold & Gorski 1984, Lephart 1996.…”

Section: Introductionmentioning

confidence: 99%

Oestrogen at the neonatal stage is critical for the reproductive ability of male mice as revealed by supplementation with 17beta-oestradiol to aromatase gene (Cyp19) knockout mice

Toda¹,

Okada²,

Takeda³

et al. 2001

Journal of Endocrinology

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Aromatase P450 (CYP19) is an enzyme responsible for the conversion of androgens to oestrogens. We generated CYP19 knockout (ArKO) mice by targeted disruption of Cyp19 and studied the role of oestrogens in male reproductive ability. Approximately 85% of ArKO males were unable to sire offspring. However, no obvious difference was found in testicular and epididymal weights, numbers of sperm in the epididymis or the ability of sperm to fertilize eggs in vitro between wild-type and ArKO males. An examination of mating behaviour demonstrated that ArKO males showed an impairment in mounting behaviour against sexually mature females. The inability of more than 90% of ArKO males to sire offspring was reversed by repeated subcutaneous injections of 17 -oestradiol when initiated on the day of birth. The effects of 17 -oestradiol on reproduction were concentration dependent and evident when supplementation was initiated on day 7, but not on day 15 after birth. These findings suggest that oestrogens acting during neonatal life are required for normal mating behaviour in adulthood.

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“…The behavioral relevance of these two pathways depends on the species and the behavior. For example, neural aromatization of T is required for the complete expression of masculine copulatory behavior in rats (Davidson, 1969;Christensen and Clemens, 1975) and Japanese quail (Watson and Adkins-Regan, 1989). For other species, 5␣-reduction of T appears to be more critical.…”

Section: Introductionmentioning

confidence: 99%

Androgen Metabolism in the Brain of the Green Anole Lizard (Anolis carolinensis): Effects of Sex and Season

Rosen

Wade

2001

General and Comparative Endocrinology

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Blockade of Testosterone-Induced Mounting Behavior in the Male Rat with Intracranial Application of the Aromatization Inhibitor, Androst-l,4,6-triene-3,17-dione

Cited by 163 publications

References 1 publication

Sex Differences in Male-Typical Copulatory Behaviors in Response to Androgen and Estrogen Treatment in Rats

Sex Differences in Male-Typical Copulatory Behaviors in Response to Androgen and Estrogen Treatment in Rats

Oestrogen at the neonatal stage is critical for the reproductive ability of male mice as revealed by supplementation with 17beta-oestradiol to aromatase gene (Cyp19) knockout mice

Androgen Metabolism in the Brain of the Green Anole Lizard (Anolis carolinensis): Effects of Sex and Season

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