Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
J Pharmacol Exp Ther. 2012 Jan;340(1):11-8. doi: 10.1124/jpet.111.186858. Epub 2011 Sep 26.
Our recent study demonstrated that central cannabinoid receptor 1 (CB₁R) activation caused dose-related pressor response in conscious rats, and reported studies implicated the brainstem phosphatidylinositol 3-kinase (PI3K)/Akt-extracellular signal-regulated kinase 1/2 (ERK1/2) pathway in blood pressure control. Therefore, in this study, we tested the hypothesis that the modulation of brainstem PI3K/Akt-ERK1/2 signaling plays a critical role in the central CB(1)R-mediated pressor response. In conscious freely moving rats, the pressor response elicited by intracisternal (i.c.) (R)-(+)-[2,3-dihydro-5-methyl-3[(4-morpholinyl)methyl]pyrrolo[1,2,3-de]-1,4-benzoxazinyl]-(1-naphthalenyl) methanone mesylate salt (WIN55,212-2) (15 μg) was associated with significant increases in ERK1/2 phosphorylation in the rostral ventrolateral medulla (RVLM) and the nucleus tractus solitarius (NTS). In contrast, Akt phosphorylation was significantly reduced in the same neuronal pools. Pretreatment with the selective CB₁R antagonist N-(piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (AM251) (30 μg i.c.) attenuated the neurochemical responses elicited by central CB₁R activation. Furthermore, pretreatment with the ERK/mitogen-activated protein kinase kinase inhibitor 2'-amino-3'-methoxyflavone (PD98059) (5 μg i.c.) abrogated WIN55,212-2-evoked increases in blood pressure and neuronal ERK1/2 phosphorylation but not the reduction in Akt phosphorylation. On the other hand, prior PI3K inhibition with wortmannin (0.4 μg i.c.) exacerbated the WIN55,212-2 (7.5 and 15 μg i.c.) dose-related increases in blood pressure and ERK1/2 phosphorylation in the RVLM. The present neurochemical and integrative studies yield new insight into the critical role of two brainstem kinases, PI3K and ERK1/2, in the pressor response elicited by central CB₁R activation in conscious rats.
我们最近的研究表明，中枢大麻素受体 1（CB₁R）的激活会导致清醒大鼠产生剂量相关的升压反应，并报告了研究表明脑桥磷脂酰肌醇 3-激酶（PI3K）/Akt-细胞外信号调节激酶 1/2（ERK1/2）通路在血压控制中起作用。因此，在这项研究中，我们检验了这样一个假设，即脑桥 PI3K/Akt-ERK1/2 信号的调节在中枢 CB（1）R 介导的升压反应中起着关键作用。在清醒的自由活动大鼠中，颅内（i.c.）（R）-（+）-[2,3-二氢-5-甲基-3-（4-吗啉基）甲基]吡咯并[1,2,3-de]-1,4-苯并恶嗪基]-（1-萘基）甲酮甲磺酸盐（WIN55,212-2）（15μg）引起的升压反应与延髓头端腹外侧区（RVLM）和孤束核（NTS）中 ERK1/2 磷酸化的显著增加有关。相比之下，在相同的神经元池中，Akt 磷酸化显著减少。选择性 CB₁R 拮抗剂 N-（哌啶-1-基）-5-（4-碘苯基）-1-（2,4-二氯苯基）-4-甲基-1H-吡唑-3-甲酰胺（AM251）（30μg i.c.）预处理可减轻中枢 CB₁R 激活引起的神经化学反应。此外，ERK/丝裂原活化蛋白激酶激酶抑制剂 2'-氨基-3'-甲氧基黄酮（PD98059）（5μg i.c.）预处理可消除 WIN55,212-2 引起的血压升高和神经元 ERK1/2 磷酸化，但不能减少 Akt 磷酸化。另一方面，预先用wortmannin（0.4μg i.c.）抑制 PI3K 会加剧 WIN55,212-2（7.5 和 15μg i.c.）剂量相关的 RVLM 血压升高和 ERK1/2 磷酸化。这些神经化学和整合研究为两个脑桥激酶 PI3K 和 ERK1/2 在清醒大鼠中枢 CB₁R 激活引起的升压反应中的关键作用提供了新的见解。
