title: Activation of adenosine A1 receptors by drugs to lower plasma glucose in streptozotocin-induced diabetic rats.
abstract: To examine the role of the adenosine A1 receptor in glucose regulation in the absence of insulin, the present study investigated the changes of plasma glucose in male streptozotocin-induced diabetic rats (STZ-diabetic rats) using dipyridamole to increase endogenous adenosine and N6-cyclopentyladenosine (CPA) to activate the adenosine A1 receptor. Intravenous injections of dipyridamole or CPA induced a dose-dependent decrease of plasma glucose in fasting STZ-diabetic rats. Plasma glucose lowering action of dipyridamole, like that of CPA, was inhibited in a dose-dependent manner by pre-treatment with 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) or 8-(p-sulfophenyl)theophylline (8-SPT) at which block the adenosine A1 receptors. Action of the adenosine A1 receptors can thus be considered. In isolated skeletal muscle, CPA enhanced the glucose uptake in a concentration-dependent manner. Blockade of this action by DPCPX and 8-SPT again supported the mediation of the adenosine A1 receptor. Also, CPA produced an increase of glycogen synthesis in isolated soleus muscle. Moreover, CPA decreased plasma triglyceride and cholesterol levels significantly in STZ-diabetic rats. These results suggest that activation of adenosine A1 receptors can increase glucose utilization in peripheral tissues by increasing tissue uptake and glycogen synthesis to lower plasma glucose in rats lacking insulin.
authors.affiliation: Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan City, Taiwan, ROC. jtcheng@mail.ncku.edu.tw
authors.forename: J T
authors.initials: JT
authors.lastname: Cheng
authors.forename: T C
authors.initials: TC
authors.lastname: Chi
authors.forename: I M
authors.initials: IM
authors.lastname: Liu
mesh_terms: D000241:Adenosine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects*; D002784:Cholesterol / Q000097:blood; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism*; D004176:Dipyridamole / Q000008:administration & dosage; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000378:metabolism / Q000493:pharmacokinetics; D006003:Glycogen / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D058915:Purinergic P1 Receptor Antagonists; D051381:Rats; D017208:Rats, Wistar; D018047:Receptors, Purinergic P1 / Q000187:drug effects* / Q000378:metabolism; D013311:Streptozocin; D013806:Theophylline / Q000008:administration & dosage / Q000031:analogs & derivatives*; D014280:Triglycerides / Q000097:blood; D014970:Xanthines / Q000008:administration & dosage
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D014280:Triglycerides; D014970:Xanthines; C048599:N(6)-cyclopentyladenosine; D013311:Streptozocin; D004176:Dipyridamole; C031433:8-(4-sulfophenyl)theophylline; D006003:Glycogen; D002784:Cholesterol; C051360:1,3-dipropyl-8-cyclopentylxanthine; D013806:Theophylline; D005947:Glucose; D000241:Adenosine