Locatelli V, Apud J A, Gudelsky G A, Cocchi D, Masotto C, Casanueva F, Racagni G, Müller E E
J Endocrinol. 1985 Sep;106(3):323-8. doi: 10.1677/joe.0.1060323.
The effect of intracerebroventricularly (i.v.t.)-injected rat prolactin (2 micrograms/rat) on the function of tuberoinfundibular gamma-aminobutyric acid (GABA)ergic neurones was assessed in adult male rats by measuring the activity of glutamic acid decarboxylase (GAD) in the mediobasal hypothalamus (MBH) and the concentrations of GABA in hypophysial portal plasma and in the anterior pituitary gland. Fourteen hours after i.v.t. injection of rat prolactin the activity of GAD in the MBH was significantly (P less than 0.05) increased and it remained elevated for at least 16 h after injection. The mean concentrations of GABA in hypophysial portal plasma and in the anterior pituitary were twice those found in vehicle-treated controls 16 h after administration of rat prolactin; no significant effects were observed at earlier time-periods. A significant (P less than 0.01) and long-lasting decrease in endogenous plasma prolactin concentrations was detected 2 h after the i.v.t. injection of rat prolactin and the concentrations remained suppressed for up to 16 h. The present results are consistent with the concept that the activity of tuberoinfundibular GABAergic neurones is regulated, at least in part, by circulating prolactin. The ability of prolactin to accelerate the synthesis and release of GABA in the MBH might constitute a short loop feedback system by which the hormone regulates its own secretion.
通过测量成年雄性大鼠中脑基底部下丘脑（MBH）中谷氨酸脱羧酶（GAD）的活性以及垂体门脉血浆和垂体前叶中γ-氨基丁酸（GABA）的浓度，评估脑室内（i.v.t.）注射大鼠催乳素（2微克/只大鼠）对结节漏斗部GABA能神经元功能的影响。脑室内注射大鼠催乳素14小时后，MBH中GAD的活性显著（P<0.05）增加，并且在注射后至少16小时保持升高。在给予大鼠催乳素16小时后，垂体门脉血浆和垂体前叶中GABA的平均浓度是给予溶剂处理对照组的两倍；在更早的时间段未观察到显著影响。脑室内注射大鼠催乳素2小时后，检测到内源性血浆催乳素浓度显著（P<0.01）且持久降低，并且浓度在长达16小时内一直受到抑制。目前的结果与结节漏斗部GABA能神经元的活性至少部分受循环催乳素调节的概念一致。催乳素加速MBH中GABA合成和释放的能力可能构成一个短环反馈系统，通过该系统该激素调节其自身分泌。
