Lateral hypothalamic injection of GABAA antagonist induces gastric vagus-mediated hypocalcemia in the rat.
Lateral hypothalamic injection of GABAA antagonist induces gastric vagus-mediated hypocalcemia in the rat.
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下丘脑外侧注射 GABAA 拮抗剂可诱导大鼠胃迷走神经介导的低钙血症。
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
T. Hori
中科院分区：
文献类型：
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作者：
K. Shiramine;S. Aou;T. Hori
在未麻醉大鼠上研究了下丘脑外侧区（LHA）神经元参与血钙稳态调节的情况。LHA内微量注射γ-氨基丁酸A受体拮抗剂甲碘荷包牡丹碱（BM，4-40 ng × 0.5 μl-1 × 5 min-1），可降低血中游离钙浓度。总血清钙也下降后，BM注射。这种低钙效应通过双侧迷走神经切断胃分支来消除。静脉注射甲基溴化阿托品（一种毒蕈碱拮抗剂）、纳多洛尔（一种β-肾上腺素能阻滞剂）或雷尼替丁（一种组胺H2阻滞剂）可抑制BM诱导的低钙血症，而酚苄明（一种α-肾上腺素能阻滞剂）被证明无效。虽然BM的LHA内注射增加了血清胃泌素，这是已知的低钙作用，无论是分泌素或生长抑素（胃泌素释放抑制剂）阻断低钙反应。这些结果表明，LHA神经元兴奋后观察到的低钙血症是由毒蕈碱，β-肾上腺素能和组胺H2受体通过胃迷走神经介导的。
The involvement of lateral hypothalamic area (LHA) neurons in the regulation of blood calcium homeostasis was investigated in unanesthetized rats. The microinjection of the γ-aminobutyric acid A receptor antagonist bicuculline methiodide (BM, 4-40 ng ⋅ 0.5 μl-1 ⋅ 5 min-1) into the LHA decreased the blood concentration of ionized calcium. Total serum calcium also decreased after the BM injection. This hypocalcemic effect was eliminated by a bilateral vagotomy of the gastric branches. An intravenous injection of atropine methyl bromide (a muscarinic antagonist), nadolol (a β-adrenergic blocker), or ranitidine (a histamine H2 blocker) suppressed the BM-induced hypocalcemia, whereas phenoxybenzamine (an α-adrenergic blocker) proved to be ineffective. Although the intra-LHA injection of BM increased the serum gastrin, which is known to have a hypocalcemic effect, neither secretin nor somatostatin (gastrin-release inhibitors) blocked the hypocalcemic response. These results suggest that the hypocalcemia observed after the excitation of LHA neurons was mediated by muscarinic, β-adrenergic, and histamine H2 receptors through the gastric vagus.