Cerebral cholinergic control of rat arterial blood pressure in streptozotocin-induced diabetes.
Rats were made diabetic with a single intravenous injection of streptozotocin (STZ; 40 mg/Kg). Buffer treated animals were used as controls. Experiments were performed 7 and 14 days thereafter. One week diabetic rats (plasma glucose = 3.34 +/- 0.58 mg/ml), compared with control animals (plasma glucose = 0.94 +/- 0.33 mg/ml), showed higher (P less than 0.05), more prolonged and dose-dependent pressor and bradycardic responses to intracerebroventricular (icv) injection of carbachol (125, 250 and 500 ng), together with a significantly lower bradycardia after icv injection of physostigmine (1.25, 2.5 and 5 mcg). The pressor response to icv injection of physostigmine (1.25 mcg) was significantly reduced in diabetic rats. Pressor and bradycardic responses induced by angiotensin II (100 and 200 ng, icv) did not show any differences between control and diabetic animals, thus ruling out an impairment of peripheral nerve conduction. Diabetic rats exhibited higher content of acetylcholine (Ach) in the striatum (123.8 +/- 3.09 nmoles/g) and in the hypothalamus (45.7 +/- 1.31 nmoles/g). Three weeks diabetic animals (plasma glucose = 2.76 +/- 0.23 mg/ml) had neither different cardiovascular responsiveness to icv injection of muscarinic agonists nor changes in hypothalamus and striatum Ach content. Data strongly suggest that STZ-induced diabetes temporarily alters cerebral acetylcholine control of cardiovascular apparatus.
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D010275:Parasympathetic Nervous System / Q000502:physiology*; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D001786:Blood Glucose; D000804:Angiotensin II; D002217:Carbachol; D010830:Physostigmine