Effects of single and repeated application of clonazepam and diazepam independently and in combination with cyproheptadine on apomorphine stereotypy in rats.

The effects of the benzodiazepines clonazepam (CLZ) and diazepam (DZ), introduced independently and in combination with cyproheptadine (CY) upon single and repeated application on apomorphine stereotypy in rats were studied. On single application CLZ shortened the duration of apomorphine stereotypy and DZ did not change it. On repeated application (14 days) CLZ reduced stereotypy while DZ increased it. Cyproheptadine on both single and repeated application reduced apomorphine stereotypy. On single application the combination of CLZ and CY increased stereotypy and the combination of DZ and CY increased gnawing behavior. On repeated administration the combination of CLZ and CY reduced apomorphine stereotypy to a higher extent than did CLZ when applied alone. The CLZ- and DZ-induced changes in apomorphine stereotypy were determined through a mediated effect in which 5-hydroxytryptamine plays an important role.