Department of Psychology, Rutgers University, Newark, NJ 07102, USA.
Horm Behav. 2011 Jun;60(1):94-104. doi: 10.1016/j.yhbeh.2011.03.008. Epub 2011 Apr 3.
The preoptic area of the hypothalamus is a key area that produces gonadotrophin-releasing hormone (GnRH). In birds, the chicken GnRH-I-form neurons are responsible for the hypothalamus-pituitary-gonadal system, which controls reproduction. In the ring dove, electrolytic lesion in the adult hypothalamus induces neurogenesis. In this study, we determined whether adult neurogenesis is involved in repairing GnRH neurons, specifically by generating newborn cells exhibiting GnRH-I immunoreactive properties. We selectively applied electrolytic lesions to three different regions of the diencephalon, including the preoptic area, which contains GnRH-I neurons, and identified new cells (BrdU-positive cells) that co-labeled with GnRH-I-immunoreactive cells. The BrdU(+)/GnRH(+) double labeled cells were then confirmed with confocal laser analysis. In brains of both male and female ring doves we found new neurons at the lesion site of the preoptic region that were GnRH-I immunoreactive. However, the total number of GnRH neurons in the lesioned brains was less than that of sham-lesioned brains. When two other regions of the diencephalon that contain GnRH-I neurons were damaged, no recruitment of new GnRH-I neurons was detected. The rate of neurogenesis depends on the bird's reproductive phase when the lesion was applied. We found BrdU(+)/GnRH(+) double-labeled cells almost exclusively during the pre-laying phase when birds are engaged in active courtship that leads to egg laying. Our observations suggest that recruitment of GnRH immunoreactive new neurons is restricted to the hypothalamic region and is sensitive to the reproductive stage of the birds.
下丘脑的视前区是产生促性腺激素释放激素 (GnRH) 的关键区域。在鸟类中，鸡 GnRH-I 形式神经元负责下丘脑-垂体-性腺系统，控制生殖。在斑鸠中，成年下丘脑的电解损伤会诱导神经发生。在这项研究中，我们确定了成年神经发生是否参与修复 GnRH 神经元，特别是通过产生表现出 GnRH-I 免疫反应性的新生细胞。我们选择性地对三个不同的间脑区域（包括含有 GnRH-I 神经元的视前区）施加电解损伤，并鉴定了与 GnRH-I 免疫反应性细胞共标记的新细胞（BrdU 阳性细胞）。然后通过共聚焦激光分析确认 BrdU(+)/GnRH(+)双标记细胞。在雄性和雌性斑鸠的大脑中，我们在视前区损伤部位发现了新的 GnRH-I 免疫反应性神经元。然而，损伤大脑中的 GnRH 神经元总数少于假损伤大脑。当损伤另两个包含 GnRH-I 神经元的间脑区域时，未检测到新的 GnRH-I 神经元的募集。神经发生的速度取决于应用损伤时鸟类的生殖阶段。当鸟类进行积极求偶导致产卵时，我们发现 BrdU(+)/GnRH(+)双标记细胞几乎只存在于产卵前阶段。我们的观察结果表明， GnRH 免疫反应性新神经元的募集仅限于下丘脑区域，并且对鸟类的生殖阶段敏感。
