Department of Pharmacology and Toxicology, School of Medicine, East Carolina University, Greenville, North Carolina.
Alcohol Clin Exp Res. 2013 Nov;37(11):1827-37. doi: 10.1111/acer.12179. Epub 2013 Jul 26.
We tested the hypothesis that alterations of the phosphorylation/dephosphorylation profile of mitogen-activated protein kinases (MAPKs) in the rostral ventrolateral medulla (RVLM) underlie the pressor response elicited by ethanol (EtOH) microinjection into the RVLM of spontaneously hypertensive rats (SHRs). The studies were extended to determine whether acetaldehyde (ACA), the primary oxidative product of EtOH, replicates the molecular effects of EtOH within the RVLM and the consequent pressor response.
Effects of EtOH or ACA on blood pressure (BP) were evaluated in the absence or presence of selective JNK (SP600125), ERK (PD98059), p38 (SB203580), or ser/thr phosphatases (okadaic acid [OKA]) inhibitor.
Intra-RVLM EtOH (10 μg/rat) or ACA (2 μg/rat) caused a similar ERK2-dependent pressor response because EtOH or ACA-evoked increases in BP and in RVLM p-ERK2 level were abolished after pharmacologic inhibition of ERK phosphorylation. SP600125 abrogated the pressor action of EtOH, but not ACA, thus implicating JNK in EtOH action on BP. Despite EtOH enhancement of p38 phosphorylation, pharmacological studies argued against a causal role for this kinase in EtOH-evoked pressor response. RVLM phosphatase catalytic activity was not influenced by EtOH or ACA. Interestingly, pharmacologic phosphatase inhibition (OKA), which increased RVLM p-ERK2 and BP, abrogated the pressor effect of subsequently administered EtOH or ACA.
Enhancement of RVLM ERK2 phosphorylation constitutes a major molecular mechanism for the pressor response elicited by intra-RVLM EtOH or its metabolite, ACA, in conscious SHRs. Further, RVLM kinases dephosphorylation does not contribute to intra-RVLM EtOH- or ACA-evoked pressor response.
我们通过实验验证了这样一个假设，即在自发性高血压大鼠（SHR）延髓头端腹外侧区（RVLM）内，乙醇（EtOH）微注射引起的促分裂原激活的蛋白激酶（MAPKs）磷酸化/去磷酸化谱的改变是引起血压升高的原因。本研究还扩展到确定乙醛（ACA），乙醇的主要氧化产物，是否在 RVLM 内复制了乙醇的分子效应及其随后引起的血压升高反应。
在不存在或存在选择性 JNK（SP600125）、ERK（PD98059）、p38（SB203580）或丝氨酸/苏氨酸磷酸酶（冈田酸[OKA]）抑制剂的情况下，评估 EtOH 或 ACA 对血压（BP）的影响。
RVLM 内 EtOH（10μg/大鼠）或 ACA（2μg/大鼠）引起类似的 ERK2 依赖性升压反应，因为 EtOH 或 ACA 引起的 BP 和 RVLM p-ERK2 水平升高在 ERK 磷酸化的药理学抑制后被消除。SP600125 阻断了 EtOH 的升压作用，但不阻断 ACA 的升压作用，因此 JNK 参与了 EtOH 对 BP 的作用。尽管 EtOH 增强了 p38 的磷酸化，但药理学研究表明该激酶在 EtOH 引起的升压反应中没有因果作用。RVLM 磷酸酶催化活性不受 EtOH 或 ACA 的影响。有趣的是，药理学磷酸酶抑制（OKA）增加了 RVLM p-ERK2 和 BP，从而消除了随后给予的 EtOH 或 ACA 的升压作用。
RVLM ERK2 磷酸化的增强构成了在清醒 SHR 中 RVLM 内 EtOH 或其代谢物 ACA 引起的升压反应的主要分子机制。此外，RVLM 激酶去磷酸化不参与 RVLM 内 EtOH 或 ACA 引起的升压反应。
