Armstrong W E, Sladek C D, Sladek J R
Endocrinology. 1982 Jul;111(1):273-9. doi: 10.1210/endo-111-1-273.
Evidence is presented indicating that norepinephrine (NE) inhibits vasopressin (VP) release from the rat hypothalamo-neurohypophyseal explant under some, but not all, conditions in vitro. NE at 10(-5) M inhibited basal VP release and inhibited acetylcholine-induced release in a concentration-dependent fashion. However, the induction of VP release caused by the addition of NaCl (sufficient to yield a 10 mosmol/kg H2O increase in culture medium osmolality) was not reduced by NE in concentrations as high as 10(-5) M. An alpha-adrenergic receptor mediation of the inhibition of VP release by NE was suggested by the ability of phentolamine and phenoxybenzamine, but not propranolol, to block this effect. In addition, phentolamine at 10(-4) M, but not equimolar amounts of propranolol, increased VP release when added alone on day 2 of culture, but not on days 3 or 4. Histofluorescence examination of additional explants revealed that endogenous catecholamine was still present on day 2 within varicosities in the supraoptic nucleus, but diminished by days 3 and 4, suggesting that endogenous NE could influence basal VP release. The results indicate that NE can inhibit spontaneous and cholinergically stimulated VP release from the hypothalamo-neurohypophyseal explant, but osmotic stimulation renders the explants insensitive to attenuation of VP release by NE.
有证据表明，去甲肾上腺素（NE）在某些（但并非所有）体外条件下会抑制大鼠下丘脑 - 神经垂体外植体中血管加压素（VP）的释放。10⁻⁵ M的NE以浓度依赖的方式抑制基础VP释放并抑制乙酰胆碱诱导的释放。然而，添加NaCl（足以使培养基渗透压增加10 mosmol/kg H₂O）所引起的VP释放诱导，即使在高达10⁻⁵ M的NE浓度下也不会降低。酚妥拉明和酚苄明（而非普萘洛尔）能够阻断这种效应，提示NE对VP释放的抑制是由α - 肾上腺素能受体介导的。此外，在培养第2天单独添加时，10⁻⁴ M的酚妥拉明（而非等摩尔量的普萘洛尔）会增加VP释放，但在第3天或第4天则不会。对额外外植体的组织荧光检查显示，视上核内的曲张体在第2天仍存在内源性儿茶酚胺，但在第3天和第4天减少，这表明内源性NE可能影响基础VP释放。结果表明，NE可抑制下丘脑 - 神经垂体外植体自发和胆碱能刺激的VP释放，但渗透刺激使外植体对NE引起的VP释放减弱不敏感。
