Rubin B S, King J C
Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, Mass. 02111, USA.
Neuroendocrinology. 1995 Sep;62(3):259-69. doi: 10.1159/000127012.
Computer-assisted analysis was used to examine LHRH reaction product in the median eminence of young and middle-aged rats prior to and after the expected peak of the LH surge on proestrus. The area of LHRH reaction product was analyzed in 5 rostral-caudal levels (A-E) of the median eminence. The relative depletion of LHRH in the median eminence of young females on the evening compared to the afternoon of proestrus suggested LHRH neurosecretion in conjunction with the preovulatory LH surge. The pattern of depletion observed further suggested that LHRH release may occur preferentially from restricted regions of the median eminence or in a coordinated wave-like pattern. Four of the five levels of the median eminence exhibited a relative decrease in LHRH on the evening of proestrus in young females, and this time-related difference in LHRH reaction product was statistically significant in median eminence levels B and C. In contrast, little evidence of a relative depletion in LHRH reaction product from early to late proestrus was observed in the median eminence of aging animals. Moreover, the concentration of the densest LHRH reaction product appeared diminished in the median eminence of middle-aged compared to young females at the time points examined in the present study. The age-related differences observed in LHRH reaction product in the median eminence may contribute to the attenuated LH surge documented in middle-aged female rats. Whether these changes in LHRH immunoreactivity can be attributed to age-related alterations in afferents received by LHRH neuronal cell bodies or terminals or to intrinsic deficits in signalling mechanisms within LHRH neurons remains to be determined. Computer-assisted analysis of the immunocytochemical data enabled the assessment of relative changes in reaction product within specific elements of LHRH neurons in precise regions of the median eminence.
采用计算机辅助分析技术，检测年轻和中年大鼠在发情前期促黄体素峰预期出现之前及之后，其正中隆起部位的促性腺激素释放激素（LHRH）反应产物。在正中隆起的5个头-尾水平（A-E）分析LHRH反应产物的面积。与发情前期下午相比，年轻雌性大鼠在发情前期晚上正中隆起部位LHRH的相对减少，提示LHRH神经分泌与排卵前促黄体素峰有关。观察到的这种减少模式进一步表明，LHRH释放可能优先从中位隆起的受限区域或以协调的波浪状模式发生。年轻雌性大鼠发情前期晚上，正中隆起的5个水平中有4个显示LHRH相对减少，且LHRH反应产物的这种时间相关差异在正中隆起水平B和C具有统计学意义。相比之下，在老龄动物的正中隆起部位，未观察到从发情前期早期到晚期LHRH反应产物相对减少的明显证据。此外，在本研究检测的时间点，与年轻雌性相比，中年雌性大鼠正中隆起部位最密集的LHRH反应产物浓度似乎有所降低。在正中隆起部位观察到的LHRH反应产物的年龄相关差异，可能导致中年雌性大鼠促黄体素峰减弱。LHRH免疫反应性的这些变化是否可归因于LHRH神经元细胞体或终末所接收传入信号的年龄相关改变，或LHRH神经元内信号机制的内在缺陷，仍有待确定。对免疫细胞化学数据的计算机辅助分析，能够评估正中隆起精确区域内LHRH神经元特定元件中反应产物的相对变化。
