Yamashita H, Inenaga K, Okuya S, Hattori Y, Yamamoto S
Department of Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu, Japan.
Arch Histol Cytol. 1989;52 Suppl:121-7. doi: 10.1679/aohc.52.suppl_121.
The effects of angiotensin II (A II) and ANP on spontaneously active neurons in the subfornical organ (SFO), anteroventral third ventricle (AV3V) and supraoptic (SON) and paraventricular nucleus (PVN) were investigated using slice preparations and extracellular recordings. Application of A II (10(-7)M) excited the neural activity of 66% of the SFO neurons, 28% of the AV3V neurons and 44% of the SON neurons. The threshold concentration to produce responses in SFO and AV3V neuron was less than 10(-10)M, while that in SON neurons was 10(-9)M. The excitatory effects of A II were reversibly antagonized by saralasin and persisted after synaptic blockade in a low Ca2+ and high Mg2+ medium. Application of ANP (10(-7)M) inhibited the neural activity of 41% of the AV3V neurons, 22% of the PVN neurons and only 14% of the SFO neurons but had no effect on SON neurons. The threshold concentration for ANP in the AV3V was 10(-11)M. Interestingly, ANP inhibited A II induced excitation in most of the SFO neurons (87%), while ANP had little effects on their spontaneous firing rates. These results show that both peptides of A II and ANP have direct central actions on hypothalamic neurons although ANP can not directly influence magnocellular neurons, suggesting that these blood borne peptides are detected in the SFO and AV3V and that they are acting as a neurotransmitter or a neuromodulator in the central nervous system to regulate water homeostasis.
利用脑片制备和细胞外记录技术，研究了血管紧张素II（A II）和心房钠尿肽（ANP）对穹窿下器（SFO）、第三脑室前腹侧区（AV3V）、视上核（SON）和室旁核（PVN）中自发放电神经元的影响。施加A II（10⁻⁷M）可使66%的SFO神经元、28%的AV3V神经元和44%的SON神经元的神经活动兴奋。在SFO和AV3V神经元中产生反应的阈浓度小于10⁻¹⁰M，而在SON神经元中为10⁻⁹M。A II的兴奋作用可被沙拉新可逆性拮抗，并且在低钙高镁培养基中突触阻断后仍持续存在。施加ANP（10⁻⁷M）可抑制41%的AV3V神经元、22%的PVN神经元和仅14%的SFO神经元的神经活动，但对SON神经元无影响。ANP在AV3V中的阈浓度为10⁻¹¹M。有趣的是，ANP在大多数SFO神经元（87%）中抑制A II诱导的兴奋，而ANP对它们的自发放电频率影响很小。这些结果表明，A II和ANP这两种肽对下丘脑神经元都有直接的中枢作用，尽管ANP不能直接影响大细胞神经元，这表明这些血源性肽在SFO和AV3V中被检测到，并且它们在中枢神经系统中作为神经递质或神经调质来调节水平衡。
