Mulchahey J J, Neill J D
Brain Res. 1986 Oct 29;386(1-2):332-40. doi: 10.1016/0006-8993(86)90170-8.
The present study was designed to assess the contributions of the long portal vessel and neurointermediate lobe routes of dopamine delivery to the anterior pituitary gland. Dopamine levels were monitored in the anterior pituitary of anesthetized diestrus 1 rats using in vivo differential pulse voltammetry at a carbon paste electrode. Measurements were taken during control periods, following neurointermediate lobectomy and hypophysial stalk section or after inhibition of catecholamine synthesis and dopamine infusion. Neurointermediate lobectomy resulted in a slight rise in plasma prolactin and a significant fall in voltammetric current. Subsequent stalk section elevated prolactin significantly and further reduced the voltammetric output. Inhibiting catecholamine synthesis significantly elevated plasma prolactin and reduced the voltammetric current. Stepped infusions of dopamine then suppressed plasma prolactin and elevated the voltammetric output in a dose related manner. The final values of both parameters were not significantly different from pre-inhibition levels. These data provide direct estimates of the relative contributions of various vascular routes to dopamine in the anterior pituitary and support the sufficiency of dopamine as the physiological inhibitor of prolactin secretion.
本研究旨在评估多巴胺通过长门静脉和神经中间叶途径输送至垂体前叶的作用。使用碳糊电极通过体内差分脉冲伏安法监测麻醉的动情间期1期大鼠垂体前叶中的多巴胺水平。在对照期、神经中间叶切除和垂体柄切断后或儿茶酚胺合成受抑制及多巴胺输注后进行测量。神经中间叶切除导致血浆催乳素略有升高，伏安电流显著下降。随后的垂体柄切断使催乳素显著升高，并进一步降低伏安输出。抑制儿茶酚胺合成显著升高血浆催乳素并降低伏安电流。然后逐步输注多巴胺以剂量相关的方式抑制血浆催乳素并提高伏安输出。两个参数的最终值与抑制前水平无显著差异。这些数据直接估计了各种血管途径对垂体前叶多巴胺的相对贡献，并支持多巴胺作为催乳素分泌的生理抑制剂的充分性。
