Lamosová D, Zeman M, Macková M, Gwinner E
Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Ivanka pri Dunaji, Slovakia.
Experientia. 1995 Sep 29;51(9-10):970-5. doi: 10.1007/BF01921750.
The chick pineal gland exhibits circadian rhythms in melatonin synthesis under in vivo and in vitro conditions. A daily rhythm of melatonin production was first detectable in pineal glands isolated from chick embryos at embryonic day 16 and incubated under a LD cycle. All pineal glands isolated from 17-day-old and older embryos were rhythmic while no gland isolated at embryonic day 14 and 15 exhibited a daily rhythm in melatonin synthesis. Melatonin production in static cultures of embryonic pineal cells was rhythmic over 48 h if the cells were kept under a LD cycle. When embryonic pineal cells were incubated in constant darkness the rhythm in melatonin production was damped within 48 h. These results suggest that chick pineal cells from embryonic day 16 onwards are photosensitive but that the endogenous component of the melatonin rhythm is not completely developed at that age. A soluble analogue of cAMP stimulated and norepinephrine inhibited melatonin synthesis in cultured embryonic pineal cells. These findings indicate that the stimulatory and inhibitory pathways controlling melatonin synthesis in the mature pineal gland are effective in pineal cells isolated from chick embryos at least 2 days before hatching.
雏鸡松果体在体内和体外条件下，褪黑素合成呈现昼夜节律。首次在胚胎第16天从雏鸡胚胎分离出的松果体中检测到每日褪黑素产生节律，这些松果体在光暗循环条件下培养。从17日龄及以上胚胎分离出的所有松果体都有节律，而在胚胎第14天和15天分离出的松果体在褪黑素合成方面未表现出每日节律。如果胚胎松果体细胞在光暗循环条件下培养，其静态培养物中褪黑素产生在48小时内有节律。当胚胎松果体细胞在持续黑暗中培养时，褪黑素产生节律在48小时内减弱。这些结果表明，从胚胎第16天起雏鸡松果体细胞对光敏感，但在那个年龄褪黑素节律的内源性成分尚未完全发育。环磷酸腺苷（cAMP）的一种可溶性类似物刺激培养的胚胎松果体细胞中褪黑素的合成，而去甲肾上腺素则抑制其合成。这些发现表明，在孵化前至少2天从雏鸡胚胎分离出的松果体细胞中，控制成熟松果体中褪黑素合成的刺激和抑制途径是有效的。
