Holmes M M, Wade J
Neuroscience Program, Michigan State University, East Lansing, MI 48824-1101, USA.
J Neuroendocrinol. 2005 Sep;17(9):560-9. doi: 10.1111/j.1365-2826.2005.01339.x.
Androgens regulate the expression of male reproductive behaviour in diverse vertebrate species, often acting on androgen receptors (AR) to induce structural or functional changes in the nervous system and periphery. Male green anoles possess two sexually dimorphic neuromuscular systems, one controlling throat fan (dewlap) extension, which occurs during courtship, and the other mediating copulatory organ function. Although androgens are required for behavioural activation in both systems, testosterone has differential effects on the neuromuscular morphology. It increases the size of copulatory muscle fibres during the breeding season, but significant effects on dewlap muscle fibre size and motoneurone soma size in either system have not been detected. Corresponding to the lack of testosterone-induced morphological effects in the courtship system, relatively low levels of AR are expressed in the associated motoneurones. The present experiment had two goals, aiming to determine whether: (i) the other courtship and copulatory neuromuscular tissues express AR and (ii) testosterone and/or seasonal environmental changes regulate AR expression. The percentage of AR+ nuclei was evaluated in both the breeding and nonbreeding seasons in gonadally intact adult males (Experiment 1) and in castrated males treated with either testosterone or vehicle (Experiment 2). AR was extensively expressed in the dewlap and copulatory muscles, and in a high percentage of the copulatory motoneurones, but immunoreactivity did not vary across season. Testosterone increased the percentage of AR+ nuclei in the copulatory muscles of both breeding and nonbreeding males but not in the dewlap muscle or copulatory motoneurones. Finally, the target structures for both systems (cartilages and hemipenes) expressed AR in all animals. Therefore, the effects of testosterone on AR immunoreactivity suggest that up-regulation of the receptors may be important for morphological change. However, because all structures investigated in the present experiment expressed AR, the data also indicate that the receptors are involved with other functions.
雄激素调节多种脊椎动物物种中雄性生殖行为的表达，通常作用于雄激素受体（AR），以诱导神经系统和外周的结构或功能变化。雄性绿安乐蜥拥有两种性别二态性神经肌肉系统，一种控制求偶时出现的喉部扇动（喉扇）伸展，另一种调节交配器官功能。虽然两种系统中的行为激活都需要雄激素，但睾酮对神经肌肉形态有不同影响。它在繁殖季节增加交配肌纤维的大小，但在任何一个系统中均未检测到对喉扇肌纤维大小和运动神经元胞体大小有显著影响。与求偶系统中缺乏睾酮诱导的形态学效应相对应，相关运动神经元中AR的表达水平相对较低。本实验有两个目标，旨在确定：（i）其他求偶和交配神经肌肉组织是否表达AR，以及（ii）睾酮和/或季节性环境变化是否调节AR表达。在性腺完整的成年雄性（实验1）以及用睾酮或载体处理的去势雄性（实验2）的繁殖和非繁殖季节中，评估AR + 细胞核的百分比。AR在喉扇肌和交配肌以及高比例的交配运动神经元中广泛表达，但免疫反应性在不同季节没有变化。睾酮增加了繁殖和非繁殖雄性交配肌中AR + 细胞核的百分比，但在喉扇肌或交配运动神经元中没有增加。最后，两个系统的靶结构（软骨和半阴茎）在所有动物中均表达AR。因此，睾酮对AR免疫反应性的影响表明，受体的上调可能对形态变化很重要。然而，由于本实验中研究的所有结构都表达AR，数据还表明这些受体参与其他功能。
