Lemaire V, Taylor G T, Mormède P
Génétique du Stress et Neurobiologie de l'Adaptation, INSERM-INRA-Université de Bordeaux II, Institut François Magendie de Neurosciences, France.
Psychoneuroendocrinology. 1997 Nov;22(8):563-73. doi: 10.1016/s0306-4530(97)00051-6.
Stress in males via the hypothalamic-pituitary-adrenal (HPA) axis may set into motion varied physiological alterations, including dysfunction of the hypothalamic-pituitary-gonadal (HPG) axis. However, the influence of the HPA on the HPG axis may not always be inhibitory. Presence or absence of stimuli of sexual significance that typically activates the HPG axis may alter the influence of the adrenal axis on gonadal axes. In this project, we used male rats and chronic social stimulation that included brief or extended periods with female rats to examine HPA-HPG axes interactions. In experiment 1, we used intact males and a 'chronic social stress' paradigm developed in our previous research that induces social instability by daily changing the membership of group-housed males with females. Thymus weight was reduced and corticosterone levels were marginally increased by chronic social stress, indicating a HPA axis hyperactivity. The HPG axis was also activated as shown by the increased weight of the androgen-sensitive sex structures. These results indicate that when these two axes are stimulated together, neither interferes with nor suppresses activities of the other. Implants of corticosterone pellets to adrenalectomized animals that maintained constant, high corticosterone levels failed to reverse the gonadal hyperactivity induced by sexual stimulation. In a second experiment, we studied the influence of different intensity of sexual stimulations on HPA-HPG axes interactions. Increased corticosterone levels and adrenal weight, indicating a HPA hyperactivity, failed to inhibit HPG hyperactivity as measured by the increased sexual organs weight, whatever the sexual intensity of the stimulation. This work demonstrates that the gonadal axis is freed from suppression when sexual stimulation occurs together with stress. The general conclusion is that the nature of complex social settings is important in determining interactions between the two neuroendocrine axes.
雄性通过下丘脑 - 垂体 - 肾上腺（HPA）轴产生的应激可能引发多种生理改变，包括下丘脑 - 垂体 - 性腺（HPG）轴功能障碍。然而，HPA对HPG轴的影响并非总是抑制性的。具有性意义的刺激的存在与否（通常会激活HPG轴）可能会改变肾上腺轴对性腺轴的影响。在本项目中，我们使用雄性大鼠和慢性社会刺激（包括与雌性大鼠短暂或长时间相处）来研究HPA - HPG轴的相互作用。在实验1中，我们使用了完整的雄性大鼠以及我们之前研究中开发的“慢性社会应激”范式，该范式通过每天改变与雌性大鼠同笼饲养的雄性大鼠群体成员来诱导社会不稳定。慢性社会应激使胸腺重量减轻，皮质酮水平略有升高，表明HPA轴功能亢进。HPG轴也被激活，表现为雄激素敏感的性器官重量增加。这些结果表明，当这两个轴同时受到刺激时，它们既不会相互干扰也不会抑制对方的活动。给肾上腺切除的动物植入维持恒定高皮质酮水平的皮质酮丸剂，未能逆转性刺激诱导的性腺功能亢进。在第二个实验中，我们研究了不同强度的性刺激对HPA - HPG轴相互作用的影响。皮质酮水平和肾上腺重量增加，表明HPA功能亢进，但无论刺激的性强度如何，都未能抑制以性器官重量增加衡量的HPG功能亢进。这项工作表明，当性刺激与应激同时发生时，性腺轴不受抑制。总体结论是，复杂社会环境的性质在决定这两个神经内分泌轴之间的相互作用方面很重要。
