Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14049-900 Ribeirão Preto, SP, Brazil.
Brain Res Bull. 2010 Jul 30;82(5-6):271-8. doi: 10.1016/j.brainresbull.2010.05.009. Epub 2010 May 26.
arginine-vasopressin in the parvocellular neurons of the hypothalamic paraventricular nucleus is known to play an important role in the control of the hypothalamo-pituitary-adrenal axis. In the present study, we verify plasma corticosterone levels, the distribution of glucocorticoid receptor- and arginine-vasopressin-positive neurons, and the co-localization of both glucocorticoid receptors and arginine-vasopressin in neurons in the anterior and medial parvocellular subdivisions of the paraventricular nucleus after manipulations of the hypothalamus-pituitary-adrenal axis. Normal, sham surgery, and adrenalectomized male rats were subjected to intraperitoneal injections of saline or dexamethasone to measure plasma corticosterone levels by a radioimmunoassay. We also examined arginine-vasopressin and glucocorticoid receptor immunofluorescence in sections from the paraventricular nucleus. Our results showed that the immunoreactivity of arginine-vasopressin neurons increased in the anterior parvocellular subdivision and decreased in the medial parvocellular subdivision from adrenalectomized rats treated with dexamethasone. On the other hand, we showed that the immunoreactivity of glucocorticoid receptors increased in the anterior and medial parvocellular subdivisions of these same animals. However, the immunoreactivity of glucocorticoid receptors is higher in the medial parvocellular than anterior parvocellular subdivision. The co-localization of arginine-vasopressin and glucocorticoid receptors was found only in the medial parvocellular subdivision. These findings indicate that glucocorticoids have direct actions on arginine-vasopressin-positive neurons in the medial parvocellular but not anterior parvocellular subdivision. There is a differentiated pattern of arginine-vasopressin-positive neuron expression between the anterior and medial parvocellular subdivisions.
已知下丘脑室旁核的小细胞神经元中的精氨酸加压素在控制下丘脑-垂体-肾上腺轴中发挥重要作用。在本研究中，我们验证了下丘脑-垂体-肾上腺轴操作后，血浆皮质酮水平、糖皮质激素受体和精氨酸加压素阳性神经元的分布以及前核和内侧核小细胞亚区神经元中糖皮质激素受体和精氨酸加压素的共定位。正常、假手术和肾上腺切除术雄性大鼠接受腹腔内注射生理盐水或地塞米松，通过放射免疫测定法测量血浆皮质酮水平。我们还检查了室旁核切片中的精氨酸加压素和糖皮质激素受体免疫荧光。结果显示，地塞米松处理的肾上腺切除术大鼠前核小细胞亚区的精氨酸加压素神经元的免疫反应性增加，而内侧核小细胞亚区的精氨酸加压素神经元的免疫反应性降低。另一方面，我们表明，这些相同动物的前核和内侧核小细胞亚区中的糖皮质激素受体的免疫反应性增加。然而，内侧核小细胞亚区的糖皮质激素受体的免疫反应性高于前核小细胞亚区。精氨酸加压素和糖皮质激素受体的共定位仅在前核小细胞亚区中发现。这些发现表明，糖皮质激素对内侧核小细胞但不是前核小细胞亚区的精氨酸加压素阳性神经元具有直接作用。前核和内侧核小细胞亚区之间存在精氨酸加压素阳性神经元表达的分化模式。
