The effect of chlordiazepoxide and propranolol on glycemic conditioning in rats

A tendency toward conditioned hyperglycemia occurred in rats with a history of insulin administration in a novel environment. This response was accentuated in rats that received propranolol (5 mg/kg) pretreatment either during the conditioning phase only or both during the conditioning phase and on the test day. Pretreatment with chlordiazepoxide (CDP; 10 mg/kg) either during the conditioning phase only or on the test day only eliminated conditioning, whereas in a previous experiment, pretreatment with CDP (same dose) during both the conditioning phase and on the test day reversed the conditioned hyperglycemic response to one of conditioned hypoglycemia. Other results included the following: (1) CDP pretreatment reduced the novelty-induced elevation of plasma glucose, but not of corticosterone; (2) CDP pretreatment reliably interfered with insulin-induced hypoglycemia; (3) first-time administration of propranolol on the test day for conditioning raised plasma glucose levels; (4) a shift from CDP to saline pretreatment on the test day for conditioning raised corticosterone levels; (5) habituation to environmental novelty was evident in the corticosterone measure, but not in the plasma glucose measure.