Beta-adrenoceptor blockade and open-field behavior in male golden hamsters

Open-field behavior was compared between untreated, saline-treated, and butoxamine (a beta-2-adrenoceptor antagonist) treated (15 and 5 mg/kg body weight) male golden hamsters (Mesocricetus auratus). Butoxamine-treated males spent significantly more time self-grooming than saline-treated and untreated males. Especially, untreated males and very similar saline control males showed a clear time sequential structure of behavior with two axes: a grooming-grooming sequence and a highly organized flankmark followed by scrape axis. The degree of this organization was markedly decreased in the butoxamine-treated males, showing an increase in organization of the transition between grooming acts. In general, these males displayed a more stereotypic pattern of behavior than the other. To reveal a systematic relation between the flankmark-scrape response and the exposition to butoxamine and to keep the numbers of experimental animals low, mixed samples were created through consecutive summing of the individual transition matrices of six males treated with 5 mg/kg b.wt. butoxamine to the 15 mg/kg b.wt. sample. By analyzing all samples separately, a positive linear relation between the number of low dosed males in the samples and the degree of organization of the flankmark-scrape sequence was found. The results suggest that the analysis of the transitional structure of behavior during short-term challenges can considerably contribute to an estimation of the coping style and seems to be a more sensitive method than comparing frequencies of behavioral indicators of stress.