Chan Jessica J, Farmer Pam J, Southwell Bridget R, Sourial Magdy, Hutson John M
Douglas Stephens Surgical Research Laboratory, Murdoch Childrens Research Institute, Melbourne, Victoria 3052, Australia.
J Pediatr Surg. 2009 Aug;44(8):1497-501. doi: 10.1016/j.jpedsurg.2008.11.039.
Testicular descent is proposed to occur in 2 stages. During the second stage, calcitonin gene-related peptide (CGRP) released from the genitofemoral nerve (GFN) causes maximal mitosis in the gubernacular bulb. As normal development requires a balance between cell proliferation and apoptosis, this study explored the effect of CGRP on apoptosis in the rat gubernacular bulb.
Gubernacula were collected from male Sprague-Dawley rats at birth (D0) or 2 days post birth (D2), and placed in organ culture for 24 hours with or without CGRP (0.001 mol/L). The D2 rats were pretreated with capsaicin (sensory nerve toxin) or flutamide (antiandrogen) or untreated. D0 rats were untreated (n = 64). Sections of the bulb were stained using the TUNEL method to identify apoptotic cells. Apoptosis was calculated as the percentage of positive cells per hundred cells.
Normal Sprague-Dawley rat gubernacula showed reduced apoptosis when cultured with CGRP, in D0 (7.0% vs 4.8%, P < .05) and D2 (4.9% vs 2.3%, P < .001). Greater apoptosis occurred at D0 compared to D2, without CGRP added (7.0% vs 4.9%, P < .05) and with CGRP (4.8% vs 2.3%, P < .001). For D2 gubernacula, capsaicin treatment increased apoptosis compared to controls, without CGRP added (4.9% vs 7.3%, P < .05) and with CGRP (2.3% vs 6.7%, P < .001). There was no difference in apoptosis when cultured with or without CGRP (7.3% vs 6.7%, nonsignificant) after capsaicin treatment. Flutamide treatment increased apoptosis compared to controls, but only with CGRP (2.3% vs 7.3%, P < .001). There was no difference in apoptosis when cultured with or without CGRP (7.1% vs 7.3%, nonsignificant) after flutamide.
Calcitonin gene-related peptide (CGRP) acts as a survival factor in the rat gubernaculum, possibly to steer cells away from a defined apoptotic pathway. Greater apoptosis occurs earlier in development. However, in vivo CGRP released from the genitofemoral nerve may be required to prevent apoptosis, as shown by pretreatment with the sensory nerve toxin capsaicin. Androgen is also involved in the pathway controlling apoptosis, as androgen blockade with flutamide inhibited the action of CGRP.
睾丸下降过程被认为分两个阶段进行。在第二阶段，从生殖股神经（GFN）释放的降钙素基因相关肽（CGRP）会使提睾肌球部出现最大程度的有丝分裂。由于正常发育需要细胞增殖和凋亡之间保持平衡，本研究探讨了CGRP对大鼠提睾肌球部细胞凋亡的影响。
从出生时（D0）或出生后2天（D2）的雄性Sprague-Dawley大鼠收集提睾肌，并在有或无CGRP（0.001 mol/L）的情况下进行器官培养24小时。对D2大鼠用辣椒素（感觉神经毒素）或氟他胺（抗雄激素）进行预处理或不进行处理。D0大鼠不做处理（n = 64）。使用TUNEL法对球部切片进行染色以识别凋亡细胞。凋亡率以每百个细胞中阳性细胞的百分比计算。
正常Sprague-Dawley大鼠提睾肌在与CGRP一起培养时，凋亡减少，在D0时（7.0%对4.8%，P <.05）和D2时（4.9%对2.3%，P <.001）。在不添加CGRP时，D0时的凋亡比D2时更多（7.0%对4.9%，P <.05），添加CGRP时也是如此（4.8%对2.3%，P <.001）。对于D2提睾肌，与对照组相比，辣椒素处理增加了凋亡，不添加CGRP时（4.9%对7.3%，P <.05），添加CGRP时（2.3%对6.7%，P <.001）。辣椒素处理后，无论有无CGRP培养，凋亡均无差异（7.3%对6.7%，无统计学意义）。氟他胺处理与对照组相比增加了凋亡，但仅在添加CGRP时（2.3%对7.3%，P <.001）。氟他胺处理后，无论有无CGRP培养，凋亡均无差异（7.1%对7.3%，无统计学意义）。
降钙素基因相关肽（CGRP）在大鼠提睾肌中起存活因子的作用，可能引导细胞远离特定的凋亡途径。在发育早期凋亡更多。然而，如用感觉神经毒素辣椒素预处理所示，可能需要生殖股神经释放的体内CGRP来预防凋亡。雄激素也参与控制凋亡的途径，因为用氟他胺阻断雄激素会抑制CGRP的作用。
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