Effects of anxiolytic compounds of diverse chemical classes (chlordiazepoxide, buspirone, ritanserin, propranolol and BRL46470) on the behaviour of mice were examined in several animal models of anxiety. These models included social interaction by male mice in the animal's home cage and an unfamiliar neutral cage, the light/dark box and responsiveness of the mice to calls from predatory and non-predatory birds. Effects of anxiolytics were also examined in mice in the timid female paradigm, and on the behaviour of marmosets when confronted with their unfamiliar conspecifics. Effects of anxiolytics in mice were compared with those of quinpirole, given at anxiogenic dose levels. The results showed that during social interaction, anxiolytic compounds released behaviour of animals that normally was suppressed by social and environmental constraints. In male mice, anxiolytics also increased exploratory digging and in some cases enhanced aggression. Quinpirole, however, in these models, decreased their social investigation, non-social activities as well as locomotor activities while increasing their flight behaviour. In the present studies, the light/dark box model was found to be sensitive to chlordiazepoxide and several other anxiolytics after acute administration. Effects of three classical antidepressants (imipramine, phenelzine, mianserin) on social interaction in male mice were also screened, using similar ethological techniques. It was found that the effects of antidepressants following different time courses were different from the effects of anxiolytics. When given acutely, antidepressants induced a range of diverse changes to behaviour which included anxiogenic-like effects, such as decrease of aggressive behaviour and social investigation. After subchronic administration, antidepressants exhibited anxiolytic-like effects in that they increased social investigation and sometimes increased aggression. Enhancement of exploratory digging was found only by subchronic administration of one of the antidepressants tested. Commonalities in the behavioural effects induced by anxiolytics and antidepressants when given by long-term administration indicate that they may be acting at common pathways in the central nervous system. They may act to suppress functioning of the behavioural inhibition system and also influence the hippocampal-5-HT defence reactions. The dissimilarities of behavioural effects produced by anxiolytics and antidepressants suggest that these drugs may alter defensive responding via different neurochemical routes
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:386273 |
| Date | January 1994 |
| Creators | Gao, Beirong |
| Publisher | Glasgow Caledonian University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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