TY - JOUR
T1 - Are rapid changes in gonadal testosterone release involved in the fast modulation of brain estrogen effects?
AU - Cornil, Charlotte A.
AU - Stevenson, Tyler J.
AU - Ball, Gregory F.
N1 - Funding Information:
The authors thank Drs. Jacques Balthazart and Mélanie Taziaux for their helpful discussions and advices throughout this study as well as Dr. Thierry D. Charlier and two anonymous reviewers for their thorough reading and comments on a previous version of this manuscript. This work is supported by a grant from the NIH (R01 MH 50388). C.A.C. is a F.N.R.S. Postdoctoral Researcher and T.J.S. is supported by an NSERC PGS-D 334570.
PY - 2009/9/15
Y1 - 2009/9/15
N2 - Estradiol facilitates the expression of male sexual behavior in Japanese quail within a few minutes. These rapid behavioral effects of estradiol could result from rapid changes in its local production in the preoptic area by aromatase, the enzyme converting testosterone into estradiol. Alternatively, aromatase activity may remain constant but fluctuations of local estradiol production could arise from rapid changes in the concentration of the enzymatic substrate, namely testosterone. Rapid increases of circulating testosterone levels have been observed in males of various species following social encounters. Surprisingly, in quail, the interaction with a female seems to result in a decrease in circulating testosterone levels. However, in that study conducted in quail, the samples were collected at intervals longer than the recently observed rapid effects of estradiol on sexual behavior. In the present study we investigated whether plasma testosterone concentrations fluctuate on a shorter time-frame. Eleven male were tested 5 min before and 5, 15 or 30 min after being allowed to have visual access to a female or to copulate with a female for 5 min. Both types of interactions resulted in a significant decline in circulating testosterone levels at latencies as short as 5 min. These data demonstrate that the decrease in testosterone levels is initiated shortly after sexual encounters. Because visual interactions with a female did not result in a rapid increase in testosterone concentrations, these findings rule out the possibility that a rapid rise in circulating testosterone levels participates in the rapid increase in brain estrogen synthesis and its facilitatory effects on copulatory behavior.
AB - Estradiol facilitates the expression of male sexual behavior in Japanese quail within a few minutes. These rapid behavioral effects of estradiol could result from rapid changes in its local production in the preoptic area by aromatase, the enzyme converting testosterone into estradiol. Alternatively, aromatase activity may remain constant but fluctuations of local estradiol production could arise from rapid changes in the concentration of the enzymatic substrate, namely testosterone. Rapid increases of circulating testosterone levels have been observed in males of various species following social encounters. Surprisingly, in quail, the interaction with a female seems to result in a decrease in circulating testosterone levels. However, in that study conducted in quail, the samples were collected at intervals longer than the recently observed rapid effects of estradiol on sexual behavior. In the present study we investigated whether plasma testosterone concentrations fluctuate on a shorter time-frame. Eleven male were tested 5 min before and 5, 15 or 30 min after being allowed to have visual access to a female or to copulate with a female for 5 min. Both types of interactions resulted in a significant decline in circulating testosterone levels at latencies as short as 5 min. These data demonstrate that the decrease in testosterone levels is initiated shortly after sexual encounters. Because visual interactions with a female did not result in a rapid increase in testosterone concentrations, these findings rule out the possibility that a rapid rise in circulating testosterone levels participates in the rapid increase in brain estrogen synthesis and its facilitatory effects on copulatory behavior.
KW - Bird
KW - Male sexual behavior
KW - Radioimmunoassay
KW - Testosterone
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U2 - 10.1016/j.ygcen.2009.04.029
DO - 10.1016/j.ygcen.2009.04.029
M3 - Article
C2 - 19416729
AN - SCOPUS:67649577473
SN - 0016-6480
VL - 163
SP - 298
EP - 305
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
IS - 3
ER -