The effects of strain differences and emotional status of rats on the behavioural and neurochemical effects of chronic treatment with apomorphine

Abstract

1. 1. Male Wistar rats, when treated chronically with apomorphine, develop two distinct behavioural responses, namely stereotyped sniffing or ritualized fighting. 2. 2. The “open field” apparatus was used to assess the emotionality of the Wistar rats by determining the changes in ambulation, grooming and defecation. No correlation was found between the emotionality of the rats and their nature of their stereotyped behaviour when they were subsequently treated with apomorphine. 3. 3. Unlike the Wistar strain, Male Sprague Dawley rats only exhibited sniffing stereotyped when chronically treated with apomorphine. 4. 4. The effect of chronic apomorphine administration on changes in the concentration of noradrenaline, serotonin, dopamine and γ -aminobutyric acid in the striatum, olfactory tubercle and mid-brain of both the Wistar and Sprague-Dawley rats was determined. Although changes occurred in the concentrations of these neurotransmitters in both strains of rat, there appeared to be no correlation between these changes in any of the brain areas and the nature of the stereotyped observed. 5. 5. From these studies, it would appear that Wistar rats are more susceptible to the behavioural and neurochemical effects of apomorphine than those of the Sprague-Dawley strain.