| Budget Amount *help |
¥15,900,000 (Direct Cost: ¥15,900,000)
Fiscal Year 2005: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2004: ¥12,900,000 (Direct Cost: ¥12,900,000)
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| Research Abstract |
To understand thermal regulation of neonatal chicks, the contribution of thyrotropin-releasing hormone (TRH), a key regulator of the hypothalamus-pituitary-thyroid axis, was investigated. Intracerebroventricular (i.c.v.) injection of TRH increased body temperature, but did not change plasma triiodothyronine (T_3) and thyroxine (T_4) concentrations. Intraperitoneal (i.p.) injection of T_3 and T_4 did not influence body temperature. Thereafter, the relationships between TRH and the hypothalamus-pituitary-adrenal axis and sympathetic nervous system were further investigated. Central TRH stimulated both corticosterone and epinephrine release. The i.c.v. injection of a corticotropin-releasing factor receptor antagonist attenuated the change in body temperature and corticosterone concentration caused by TRH, but did not influence plasma T_3 and T_4 concentrations. The i.p. injection of epinephrine did not induce hyperthermia. Therefore, the thermoregulatory response to TRH may differ in neonatal stages being dependent upon the stimulation of the hypothalamus-pituitary-adrenal axis rather than the hypothalamus-pituitary-thyroid axis. Heat production during embryonic stages were influenced by genetic selection. On the other hand, nutrients influencing chick behaviors were found out. Carnosine inhibited food intake and iduced hyperactiveity. The constituents of carnosine, β-alanine (β-Ala) and L-histidine (His), also inhibited food intake, whereas β-Ala plus His induced hypoactivity manifested as sleep-like behavior. Central creatine, phosphatidylserine, L-serine and (-)-epigallocatechin gallate reduced the stress responses in chicks.
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