MODULATION OF SPATIAL ALTERNATION AND ANXIETY BY SEPTAL SCOPOLAMINE SYSTEMIC DIAZEPAM IN MICE

To investigate the behavioral consequences of benzodiazepines in subje cts whose septo-hippocampal cholinergic (ACh) activity was impaired, C 57BL/6 mice received an injection of 2.5 mu g/0.2 mu l of scopolamine into the medial septal area with an IP injection of 0.5 mg/kg of diaze pam. The consequences of these treatments administered in combination or alone were evaluated on anxiety measured in an elevated plus-maze a nd on spontaneous alternation carried out in a T-maze, using two diffe rent intertrial intervals (ITI: 5s or 30s). In these conditions, only the combined treatment provoked a decrease of the anxiety level; which was associated with an impairment of spontaneous alternation restrict ed to the 5s ITI. Because mice were not impaired during the sequential 30s ITI, this seems to rule out the possibility that this alternation deficit resulted from a working memory loss. These results suggest an involvement of a septal ACh-GABA-A/BDZ interaction in the exaggeratio n of cognitive deficits produced by benzodiazepines in patients charac terized by a cholinergic hypofunction. (C) 1998 Elsevier Science Inc.