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外侧隔区 α1-和 α2-肾上腺素受体对未麻醉大鼠压力反射活动的调节作用不同。

Lateral septal area α1- and α2-adrenoceptors differently modulate baroreflex activity in unanaesthetized rats.

机构信息

Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.

出版信息

Exp Physiol. 2012 Sep;97(9):1018-29. doi: 10.1113/expphysiol.2011.062315. Epub 2011 Dec 16.

Abstract

The lateral septal area (LSA) is a limbic structure involved in autonomic, neuroendocrine and behavioural responses. An inhibitory influence of the LSA on baroreflex activity has been reported; however, the local neurotransmitter involved in this modulation is still unclear. In the present study, we verified the involvement of local LSA adrenoceptors in modulating cardiac baroreflex activity in unanaesthetized rats. Bilateral microinjection of the selective α(1)-adrenoceptor antagonist WB4101 (10 nmol in a volume of 100 nl) into the LSA decreased baroreflex bradycardia evoked by blood pressure increases, but had no effect on reflex tachycardia evoked by blood pressure decreases. Nevertheless, bilateral administration of the selective α(2)-adrenoceptor antagonist RX821002 (10 nmol in 100 nl) increased baroreflex tachycardia without affecting reflex bradycardia. Treatment of the LSA with a cocktail containing WB4101 and RX821002 decreased baroreflex bradycardia and increased reflex tachycardia. The non-selective β-adrenoceptor antagonist propranolol (10 nmol in 100 nl) did not affect either reflex bradycardia or tachycardia. Microinjection of noradrenaline into the LSA increased reflex bradycardia and decreased the baroreflex tachycardic response, an opposite effect compared with those observed after double blockade of α(1)- and α(2)-adrenoceptors, and this effect of noradrenaline was blocked by local LSA pretreatment with the cocktail containing WB4101 and RX821002. The present results provide advances in our understanding of the baroreflex neural circuitry. Taken together, data suggest that local LSA α(1)- and α(2)-adrenoceptors modulate baroreflex control of heart rate differently. Data indicate that LSA α(1)-adrenoceptors exert a facilitatory modulation on baroreflex bradycardia, whereas local α(2)-adrenoceptors exert an inhibitory modulation on reflex tachycardia.

摘要

外侧隔核(LSA)是一个参与自主神经、神经内分泌和行为反应的边缘结构。已经报道了 LSA 对压力反射活动的抑制影响;然而,涉及这种调节的局部神经递质仍不清楚。在本研究中,我们验证了局部 LSA 肾上腺素受体在调节未麻醉大鼠心脏压力反射活动中的作用。将选择性α(1)-肾上腺素受体拮抗剂 WB4101(10 nmol,体积 100 nl)双侧微注射到 LSA 中,降低了血压升高引起的压力反射性心动过缓,但对血压降低引起的反射性心动过速没有影响。然而,双侧给予选择性α(2)-肾上腺素受体拮抗剂 RX821002(10 nmol,100 nl)增加了压力反射性心动过速而不影响反射性心动过缓。用包含 WB4101 和 RX821002 的鸡尾酒处理 LSA,降低了压力反射性心动过缓,增加了反射性心动过速。非选择性β-肾上腺素受体拮抗剂普萘洛尔(10 nmol,100 nl)对反射性心动过缓和心动过速都没有影响。去甲肾上腺素微注射到 LSA 中增加了反射性心动过缓,并降低了压力反射性心动过速反应,与α(1)-和α(2)-肾上腺素受体双重阻断后观察到的相反效果,这种去甲肾上腺素的作用被包含 WB4101 和 RX821002 的鸡尾酒预先处理 LSA 所阻断。本研究结果加深了我们对压力反射神经回路的理解。综合数据表明,局部 LSA α(1)-和 α(2)-肾上腺素受体对心率的压力反射控制有不同的调节作用。数据表明,LSA α(1)-肾上腺素受体对压力反射性心动过缓产生促进调节作用,而局部 α(2)-肾上腺素受体对反射性心动过速产生抑制调节作用。

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