Inhibitory Avoidance Impairments Induced by Intra-Amygdala Propranolol Are Reversed by Glutamate but Not Glucose

• Published in: Behavioral neuroscience 1996-10, Vol.110 (5), p.1033-1039
• Main Authors: Lennartz, Robert C, Hellems, Kristen L, Mook, Evan R, Gold, Paul E
• Format: Article
• Language: English
• Subjects: Adrenergic beta-Antagonists - pharmacology; Amygdala; Amygdala - drug effects; Animal; Animals; Avoidance Conditioning; Avoidance Learning - drug effects; Behavioral psychophysiology; Biological and medical sciences; Brain; Brain Mapping; Dose-Response Relationship, Drug; Fundamental and applied biological sciences. Psychology; Glucose; Glucose Solution, Hypertonic - pharmacology; Glutamic Acid - pharmacology; Injections; Male; Maze Learning - drug effects; Memory; Neural Inhibition - drug effects; Neurology; Neurotransmission and behavior; Pain Threshold - drug effects; Propranolol; Propranolol - antagonists & inhibitors; Propranolol - pharmacology; Psychology; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Sprague-Dawley; Reaction Time - drug effects; Retention (Psychology) - drug effects; Sugar
• ISSN: 0735-7044; 1939-0084
• DOI: 10.1037/0735-7044.110.5.1033

Both systemic and central injections of glucose can enhance memory. For example, glucose reverses impairments on inhibitory avoidance resulting from intra-amygdala injections of morphine. The present experiment investigated the ability of glucose to reverse memory impairments resulting from intra-amygdala injections of propranolol, a β-noradrenergic antagonist. Pretraining administration of 10 μg propranolol significantly reduced inhibitory avoidance retention latencies but had no effect on performance in a spontaneous alternation task. Coadministration of glucose into the amygdala at 3 doses (1.5, 3.0, and 6.0 μg) did not reverse the propranolol-induced inhibitory avoidance deficits. However, coadministration of 2.5 μg of glutamate with the propranolol did reverse these deficits. The ability of glucose to reverse impairments following intra-amygdala injections of morphine but not propranolol may reflect the neurotransmitter system or systems through which glucose exerts its effects.