Studies on regulation of energy metabolism via central nervous system in neonatal chicks

为了解新生雏鸡的体温调节，研究了下丘脑-垂体-甲状腺轴的关键调节因子促甲状腺素释放激素（TRH）的作用。脑室内（i. c. v.）注射TRH可使体温升高，但对血浆T_3和T_4浓度无明显影响。腹膜内（i. p.）注射T_3、T_4对体温无影响。随后，进一步研究了TRH与下丘脑-垂体-肾上腺轴和交感神经系统的关系。中枢TRH刺激皮质酮和肾上腺素的释放。静脉注射促肾上腺皮质激素释放因子受体拮抗剂可减轻TRH引起的体温和皮质酮浓度的变化，但不影响血浆T_3和T_4浓度。腹腔注射肾上腺素不会引起体温过高。因此，TRH的体温调节反应在新生儿阶段可能不同，取决于下丘脑-垂体-肾上腺轴的刺激，而不是下丘脑-垂体-甲状腺轴。胚胎期产热受遗传选择的影响。另一方面，找出了影响雏鸡行为的营养成分。肌肽抑制食物摄入并引起多动。肌肽成分β-丙氨酸（β-Ala）和L-组氨酸（His）也能抑制摄食，而β-Ala和His联合作用则能引起活动减退，表现为睡眠样行为。中枢肌酸、磷脂酰丝氨酸、L-丝氨酸和（-）-表没食子儿茶素没食子酸酯降低雏鸡的应激反应。

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.