Water maze impairments after combined depletion of somatostatin and serotonin in the rat.
This study examined the effect of both separate and combined depletion of brain somatostatin and serotonin on acquisition of the water maze (WM) task. Naïve male Long-Evans rats received injections of p-chlorophenylalanine (PCPA; 500mg/kgx2) to deplete serotonin or cysteamine (90 or 200mg/kg) to deplete somatostatin, or both treatments prior to spatial and reversal training in the water maze. Some rats first received Morris' nonspatial pretraining to train them in the behavioral strategies that are required for successful spatial place learning in this task, prior to drug treatment and spatial training. A detailed behavioral analysis indicated that somatostatin or serotonin depletion alone caused little or no impairment in naïve animals. Depletion of both somatostatin and serotonin in naïve rats impaired performance, with differences in the impairments that depended on the dose of cysteamine. Nonspatially pretrained rats were not impaired. Thus, neither somatostatin nor serotonin alone is crucial for the water maze task, but impairments occur if both somatostatin and serotonin are depleted in naïve rats. The results indicate that some of the performance impairment was due to strategies impairment rather than a spatial place learning impairment. Depletion of both somatostatin and serotonin in naïve rats produces results comparable to the spatial navigation deficits seen in some Alzheimer patients and suggests that combinations of antagonist treatments may better model this disorder than single antagonist treatments do.
Dyer
Kelly
K
Department of Psychology and Graduate Program in Neuroscience, University of Western Ontario, London, Ontario N6A 5C2, Canada.
Cain
Donald P
DP
D000818:Animals; D001522:Behavior, Animal; D003543:Cysteamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D010134:Fenclonine / Q000494:pharmacology; D007859:Learning Disabilities / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology*; D011597:Psychomotor Performance / Q000187:drug effects; D051381:Rats; D020318:Rats, Long-Evans; D012601:Scopolamine / Q000494:pharmacology; D012701:Serotonin / Q000172:deficiency*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013004:Somatostatin / Q000172:deficiency*; D013997:Time Factors
D012702:Serotonin Antagonists; D012701:Serotonin; D013004:Somatostatin; D003543:Cysteamine; D012601:Scopolamine; D010134:Fenclonine