Effects of serotonin injected into the third ventricle on prolactin and growth hormone secretion in Holstein steers |
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| Authors: | Etsuko KASUYA Shiro KUSHIBIKI Ken-ichi YAYOU Shuichi ITO Toshiyuki SAITO Koichi HODATE Madoka SUTOH |
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| Institution: | National Institute of Agrobiological Sciences,;National Institute of Livestock and Grassland Science, Tsukuba,;Department of Animal Science, Kyushu Tokai University, Minamiaso, and;School of Veterinary Medicine, Kitasato University, Towada, Japan |
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| Abstract: | In order to clarify the role of serotonin (5-HT) in the regulation of pituitary hormones, the effects of 5-HT injected into the third ventricle (3V) on prolactin (PRL) and growth hormone (GH) release were investigated in Holstein steers. A chronic cannula was implanted in 3V by stereotaxic surgery under general anesthesia. After sufficient recovery from surgery, 5-HT (0, 0.1, 1.0, 2.0 mg) was injected into via the cannula and blood samples were collected over 4 h. Plasma PRL and GH concentrations were determined by radioimmunoassay. PRL release was significantly stimulated by the injection of 5-HT. The increase in PRL was observed at 20 min after the injection at three doses and the highest dose (2.0 mg) was the most effective in stimulating PRL release. The injection of 5-HT into 3V, at all doses tested, did not alter GH release significantly. Our results suggest that 5-HT is involved in the regulation of PRL release partly through the hypothalamus in cattle. |
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| Keywords: | growth hormone prolactin serotonin steer third ventricle |
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