Lin J Y, Yen S H, Shieh K R, Liang S L, Pan J T
Department of Physiology, School of Life Science, National Yang-Ming University, ROC, Taipei, Taiwan.
Brain Res Bull. 2000 Aug;52(6):567-72. doi: 10.1016/s0361-9230(00)00298-7.
Whether the tuberoinfundibular dopaminergic (TIDA) neurons resided in the dorsomedial arcuate nucleus (dmARN) can respond to dopamine and a dopamine D(3) receptor agonist, 7-hydroxydipropylaminotetralin (7-OH-DPAT), was the focus of this study. In studies using extracellular single-unit recording of dmARN neurons in brain slices obtained from ovariectomized rats, dopamine and 7-OH-DPAT inhibited 60.1% (n = 141) and 80.9% (n = 47) of recorded dmARN neurons, respectively. Other dopamine D(1) or D(2) receptor agonists were not as effective. Intracerebroventricular injection of 7-OH-DPAT (10(-9) mol/3 microl) in ovariectomized, estrogen-primed rats significantly lowered the TIDA neuronal activity as determined by 3, 4-dihydroxyphenylacetic acid (DOPAC) levels in the median eminence. Co-administration of a putative D(3) receptor antagonist, U-99194A, could prevent the effect of 7-OH-DPAT. Unilateral microinjection of 7-OH-DPAT or dopamine itself (10(-11)-10(-9) mol/0.2 microl) into the right dmARN exhibited the same inhibitory effect on TIDA neurons. In all, dopamine may act on D(3) receptors to exhibit an inhibitory effect on its own release from the TIDA neurons.
结节漏斗多巴胺能(TIDA)神经元是否存在于背内侧弓状核(dmARN)中并能对多巴胺和多巴胺D(3)受体激动剂7-羟基二丙基氨基四氢萘(7-OH-DPAT)产生反应,是本研究的重点。在对去卵巢大鼠脑片中dmARN神经元进行细胞外单单位记录的研究中,多巴胺和7-OH-DPAT分别抑制了60.1%(n = 141)和80.9%(n = 47)的记录dmARN神经元。其他多巴胺D(1)或D(2)受体激动剂效果不佳。在去卵巢且经雌激素预处理的大鼠中,脑室内注射7-OH-DPAT(10(-9) mol/3 μl)可显著降低结节漏斗多巴胺能神经元的活性,这由正中隆起中3,4-二羟基苯乙酸(DOPAC)水平来确定。共同给予一种假定的D(3)受体拮抗剂U-99194A可阻止7-OH-DPAT的作用。将7-OH-DPAT或多巴胺本身(10(-11)-10(-9) mol/0.2 μl)单侧微量注射到右侧dmARN中,对TIDA神经元表现出相同的抑制作用。总之,多巴胺可能作用于D(3)受体,对其自身从TIDA神经元的释放产生抑制作用。