Reiter R J, White T, Lerchl A, Stokkan K A, Rodriguez C
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78284-7762.
J Pineal Res. 1991 Oct-Nov;11(3-4):156-62. doi: 10.1111/j.1600-079x.1991.tb00472.x.
Day and nighttime melatonin production in the pineal gland was compared in normal and cardiomyopathic (polydystrophic) adult male Syrian hamsters. These strains of hamsters were selected for comparison because the cardiomyopathetic hamster displays a deficient transmembrane Ca(2+)-pump in a number of tissues, and intracellular CA2+ concentrations ([Ca2+]i) play a central role in the nocturnal increase in pineal melatonin synthesis. Daytime levels of all constituents measured, i.e., pineal N-acetyltransferase (NAT) activity, pineal and serum melatonin levels, and pineal 5-hydroxytryptophan (5-HTP), serotonin, and 5-hydroxyindole acetic acid (5-HIAA) contents, were comparable in control and dystrophic hamsters. In contrast, the nighttime rises in pineal NAT activity and pineal and serum melatonin levels were significantly attenuated in the dystrophic hamsters. By comparison, the pineal contents of 5-HTP, serotonin, and 5-HIAA were essentially the same in both groups of hamsters with both pineal serotonin and 5-HIAA values exhibiting the usual nighttime drop. It is presumed that the alterations in nocturnal melatonin production in the pineal gland of the cardiomyopathic hamster may relate to a generalized deficiency in the Ca(2+)-pump in pinealocyte plasma membranes, which leads to unusually high [Ca2+]i, causing a depression of NAT activity; this leads to the commensurate decline in pineal and serum melatonin levels. Harderian gland NAT activity and melatonin levels were essentially similar in the two groups of animals, although NAT activity was slightly depressed in the dystrophic hamsters killed during the day. The reduced amounts of intrascapular brown fat in the cardiomyopathic hamster is speculated to be a result of the diminished amount of melatonin produced in these animals.
在正常和患心肌病（多营养不良型）的成年雄性叙利亚仓鼠中，对松果体白天和夜间褪黑素的分泌情况进行了比较。选择这两种品系的仓鼠进行比较，是因为患心肌病的仓鼠在许多组织中表现出跨膜钙泵缺陷，而细胞内钙离子浓度（[Ca2+]i）在松果体褪黑素合成的夜间增加中起核心作用。所测量的所有成分的白天水平，即松果体N-乙酰转移酶（NAT）活性、松果体和血清褪黑素水平，以及松果体5-羟色氨酸（5-HTP）、血清素和5-羟吲哚乙酸（5-HIAA）含量，在对照仓鼠和患营养不良仓鼠中相当。相比之下，患营养不良仓鼠松果体NAT活性以及松果体和血清褪黑素水平的夜间升高显著减弱。相比之下，两组仓鼠松果体中5-HTP、血清素和5-HIAA的含量基本相同，两组仓鼠的松果体血清素和5-HIAA值均出现了通常的夜间下降。据推测，患心肌病仓鼠松果体夜间褪黑素分泌的改变可能与松果体细胞质膜钙泵普遍缺乏有关，这导致细胞内钙离子浓度异常升高，从而抑制NAT活性；这导致松果体和血清褪黑素水平相应下降。两组动物的哈德氏腺NAT活性和褪黑素水平基本相似，尽管白天处死的患营养不良仓鼠的NAT活性略有降低。推测患心肌病仓鼠肩胛间棕色脂肪量减少是这些动物褪黑素分泌减少的结果。
