Department of Anesthesiology, Chi-Mei Medical Center, Yong Kang, Tainan City, Taiwan, Republic of China.
J Agric Food Chem. 2011 Apr 27;59(8):3747-53. doi: 10.1021/jf200069t. Epub 2011 Mar 10.
Catalpol is one of the active principles from roots of Rehmannia glutinosa Steud (Scrophulariaceae) that is widely used to treat diabetic disorders in Chinese traditional medicine using the name of Di-Huang, which is used to investigate the mechanisms for lowering of plasma glucose in streptozotocin-induced diabetic rats (STZ-diabetic rats). Catalpol decreased plasma glucose in a dose-related manner, and this action was reduced by pretreatment with naloxone or naloxonazine. An increase of plasma β-endorphin by catalpol was also observed in parallel. The plasma glucose lowering action of catalpol was deleted in bilateral adrenalectomized rats. Moreover, catalpol enhanced β-endorphin release from the isolated adrenal medulla of STZ-diabetic rats. Otherwise, plasma glucose lowering action of catalpol failed to produce in opioid μ-receptor knockout mice. Also, repeated administration of catalpol for 3 days in STZ-diabetic rats resulted in a marked reduction of phosphoenolpyruvate carboxykinase (PEPCK) expression in liver and an increased expression of glucose transporter subtype 4 (GLUT 4) in skeletal muscle. These effects were also reversed by blockade of opioid μ-receptors. Our results suggested that catalpol increased glucose utilization through increase of β-endorphin secretion from adrenal gland in STZ-diabetic rats.
梓醇是地黄（玄参科地黄属植物）根部的一种有效成分，在中国传统医学中被广泛用于治疗糖尿病。梓醇可以降低链脲佐菌素（STZ）诱导的糖尿病大鼠（STZ-糖尿病大鼠）的血糖，其作用机制正在研究中。梓醇呈剂量依赖性降低血糖，纳洛酮或纳洛酮嗪预处理可降低其作用。梓醇还平行增加了血浆β-内啡肽。双侧肾上腺切除大鼠的梓醇降血糖作用被删除。此外，梓醇增强了 STZ-糖尿病大鼠肾上腺髓质的β-内啡肽释放。而在阿片μ-受体敲除小鼠中，梓醇的降血糖作用无法产生。另外，梓醇在 STZ-糖尿病大鼠中连续给药 3 天，导致肝脏中磷酸烯醇丙酮酸羧激酶（PEPCK）的表达显著降低，骨骼肌中葡萄糖转运体亚型 4（GLUT 4）的表达增加。这些作用也被阿片μ-受体阻断所逆转。我们的结果表明，梓醇通过增加 STZ 糖尿病大鼠肾上腺分泌β-内啡肽来增加葡萄糖的利用。
