著者

Yasuhiko Kondo Yasuo Sakuma

出版者

THE PHYSIOLOGICAL SOCIETY OF JAPAN

雑誌

The Japanese Journal of Physiology (ISSN:0021521X)

巻号頁・発行日

pp.0601160021, (Released:2006-01-17)

被引用文献数

19 29

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Partner preference and paced mating tests were accomplished in ovariectomized female rats following bilateral radiofrequency lesions in the medial amygdala. Open field behavior and passive avoidance learning were also examined to investigate the underlying behavioral mechanism. Partner preference was determined in a chamber located between castrated and sexually active males. Airborne olfactory cues were presented to the female through small holes on the partition. The lesion diminished preference for the odor of sexually active males over that of castrated males, even after injection with high-dose of estrogen. On the other hand, in a paced mating test, the lesioned females without estrogen treatment showed a significantly shorter latency for entering the male's compartment in a two-compartment apparatus, which allowed the females, but not the males, to cross the barrier through a narrow opening at the bottom. However, administration of estrogen and progesterone reduced the effect. The lesion had no effect on emotionality or exploratory behavior in an open field test, but impaired passive avoidance learning capability. We suggest that a male poses an inherent threat to a female. The seemingly incompatible results of partner preference and paced mating tests can be compromised if the male is inherently aversive to the female; this emotional response can be removed by the medial amygdala lesion.

著者

Shun Sato Chengzhu Yin Akira Teramoto Yasuo Sakuma Masakatsu Kato

出版者

PHYSIOLOGICAL SOCIETY OF JAPAN

雑誌

The Journal of Physiological Sciences (ISSN:18806546)

巻号頁・発行日

vol.58, no.5, pp.317-322, 2008 (Released:2008-10-29)

参考文献数

47

被引用文献数

7 16

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Gonadotropin-releasing hormone (GnRH) neurons represent the final output neurons in the central control of reproduction. γ-Amino butyric acid (GABA), one of the major regulators of GnRH neurons, depolarizes GnRH neurons isolated from adult rats via GABAA receptors. The presence of GABAA receptors in GnRH neurons has also been demonstrated morphologically. Furthermore, the pineal hormone melatonin is involved in the regulation of reproductive function, including the timing of the luteinizing hormone surge. The suprachiasmatic nucleus and the GABAergic system in the medial preoptic area are considered as possible sites of the action of melatonin. Until now, however, a direct action of melatonin on GnRH neurons has not been reported. Therefore we examined the effect of melatonin on GABAA receptor currents in GnRH neurons isolated from GnRH-EGFP transgenic rats by means of perforated patch-clamp experiments. The GABAA receptor currents were modulated by melatonin in a sex-specific manner. In GnRH neurons from adult males, melatonin augmented these currents in 67% of the neurons examined, but attenuated the currents in only 19% of them. These modulations were blocked by the melatonin receptor antagonist luzindole, suggesting an involvement of melatonin receptors. The modulation by melatonin was not observed in GnRH neurons isolated from infantile rats. These findings indicate that GABA affects the excitability of GnRH neurons in adult rats through GABAA receptors, and that melatonin modifies this excitability via melatonin receptors in a sex-specific manner.