Racké K, Böhm E, Hurth S, Muscholl E
Life Sci. 1986 May 12;38(19):1749-56. doi: 10.1016/0024-3205(86)90125-6.
The release of endogenous dopamine (DA) from the in vitro incubated combined neurointermediate lobe (NIL) or isolated neural lobe (NL) was studied. In the presence of the DA uptake inhibitor GBR 12921 (200 nM), electrical stimulation of the pituitary stalk caused an increase of the outflow of DA from the NIL in a frequency-dependent manner. Naloxone (1 microM) enhanced the DA release from the NIL evoked by electrical stimulation at 7 or 15 Hz by about 40%, but had no effect on DA release evoked by stimulation at 3 Hz. When the electrical stimulation was carried out at 15 Hz, the evoked DA release (expressed as fraction of the DA tissue content) from the NL amounted to only 15% of that from the combined NIL. Naloxone (1 microM) increased the evoked DA release from the isolated NL by 242%. Thus, the effect of naloxone on DA release from the combined NIL may be confined mainly to the NL. In conclusion, DA release from the NL is under inhibitory control of endogenous opioids released from the NL during stimulation at 7 or 15 Hz. Beta-Endorphin, known to be released spontaneously at a high rate from in vitro incubated NILs, appears to lack inhibitory effects on DA release from the NIL.
研究了体外孵育的联合神经中间叶（NIL）或分离的神经叶（NL）中内源性多巴胺（DA）的释放。在存在DA摄取抑制剂GBR 12921（200 nM）的情况下，电刺激垂体柄会导致DA从NIL流出的量以频率依赖性方式增加。纳洛酮（1 microM）使7或15 Hz电刺激诱发的NIL中DA释放增强约40%，但对3 Hz刺激诱发的DA释放没有影响。当以15 Hz进行电刺激时，NL诱发的DA释放（以DA组织含量的分数表示）仅为联合NIL的15%。纳洛酮（1 microM）使分离的NL中诱发的DA释放增加了242%。因此，纳洛酮对联合NIL中DA释放的作用可能主要局限于NL。总之，在7或15 Hz刺激期间，NL中DA的释放受NL释放的内源性阿片类物质的抑制性控制。已知从体外孵育的NIL中以高速率自发释放的β-内啡肽似乎对NIL中DA的释放缺乏抑制作用。
