Sensitivity to apomorphine in the guinea pig as a function of age and body weight.

Male albino guinea pigs aged 4--10 weeks were challenged with 0.1, 0.2, and 0.4 mg/kg apomorphine. Mean stereotypy scores rose signfiicantly as a function of age. Stereotypy scores were better correlated with age than with body weight, suggesting that CNS maturation, rather than weight-related factors, were responsible. Although age and body weight were correlated, there was enough variability to make bvody weight an unreliable indicator of age.