Glass J D, Ferreira S, Deaver D R
Department of Biological Sciences, Kent State University, Ohio 44242.
Endocrinology. 1988 Aug;123(2):1119-27. doi: 10.1210/endo-123-2-1119.
This study was undertaken to examine short photoperiod (SD; 8 h of light, 16 h of darkness)-induced alterations in reproductive endocrine and neuroendocrine parameters in the male white-footed mouse, Peromyscus leucopus. Exposure to SD for 8 weeks caused dramatic reductions in testis and seminal vesicle weights, decreased circulating LH and testosterone levels, and lowered the content of LH in the pituitary gland relative to those in mice under long photoperiod (LD; 16 h of light, 8 h of darkness). These changes were associated with significant increases in content of radioimmunoassayable GnRH in the mediobasal hypothalamus (MBH) and anterior hypothalamus at two time points in the light/dark cycle: 2100 h (dark phase) and 0900 h (light phase), respectively. Exposure to SD also caused an increase in radioimmunoassayable beta-endorphin in the MBH and preoptic area of the hypothalamus (POA) at 2100 h, but not at 0900 h. Mice exposed to SD also had a significantly higher metabolism of serotonin in the MBH at 0900 and 2100 h compared to mice under LD. The concentration of noradrenaline in the hypothalamus was unaffected by exposure to SD. However, the metabolism of dopamine (DA) in the POA at 0900 h was significantly increased relative to that in mice maintained under LD at this time. This increase in DA metabolism was associated with enhanced immunocytochemical staining for tyrosine hydroxylase in nerve fibers of the POA. Conversely, staining for tyrosine hydroxylase in tuberoinfundibular DA cell bodies of the arcuate nucleus was less intense under SD exposure. From these data it is concluded that exposure to SD caused regional and time-dependent alterations in the activities of hypothalamic amines (serotonin and DA) and neuropeptides (beta-endorphin and GnRH). These changes may be part of the neuroendocrine mechanism for SD-induced seasonal adaptations.
本研究旨在检测短光照周期（SD；8小时光照，16小时黑暗）对雄性白足鼠（白足鼠属）生殖内分泌和神经内分泌参数的影响。暴露于SD环境8周会导致睾丸和精囊重量显著减轻，循环促黄体生成素（LH）和睾酮水平降低，与长光照周期（LD；16小时光照，8小时黑暗）下的小鼠相比，垂体中LH含量也降低。这些变化与中基底下丘脑（MBH）和下丘脑前部在明暗周期的两个时间点（分别为21:00时（黑暗期）和09:00时（光照期））可通过放射免疫测定的促性腺激素释放激素（GnRH）含量显著增加有关。暴露于SD还会导致MBH和下丘脑视前区（POA）在21:00时可通过放射免疫测定的β-内啡肽增加，但在09:00时无此现象。与LD组小鼠相比，暴露于SD的小鼠在09:00和21:00时MBH中血清素的代谢也显著更高。下丘脑去甲肾上腺素浓度不受SD暴露影响。然而，与此时处于LD环境下的小鼠相比，POA在09:00时多巴胺（DA）的代谢显著增加。DA代谢的这种增加与POA神经纤维中酪氨酸羟化酶免疫细胞化学染色增强有关。相反，在SD暴露下，弓状核结节漏斗部DA细胞体中酪氨酸羟化酶的染色较弱。从这些数据可以得出结论，暴露于SD会导致下丘脑胺类（血清素和DA）和神经肽（β-内啡肽和GnRH）活性出现区域和时间依赖性变化。这些变化可能是SD诱导的季节性适应神经内分泌机制的一部分。
