Abnormalities of responses to autonomic stimulation in the mouse urinary bladder associated with Semliki Forest...

The responses to autonomic stimulation of the urinary bladder were studied in mice infected with Semliki Forest Virus, which has been proposed as an animal model for multiple sclerosis. Mice infected with Semliki Forest Virus showed a decreased body weight when compared with control animals, although their bladders were proportionately heavier. The pharmacological results indicated a selective change in purinergic transmission in the bladders of mice infected with Semliki Forest Virus, while cholinergic transmission remained unchanged. This was demonstrated by a significant increase in the contractile response to beta,gamma-methylene ATP accompanied by an increase in the proportion of the nerve-mediated response blocked by alpha,beta-methylene ATP. In contrast, the contractile response to acetylcholine and the atropine-sensitive component of the neurogenic response were not significantly different between the two groups of animals. Active length-tension curves were also unchanged in the mice infected with Semliki Forest Virus when compared with controls. The results are discussed in relation to those obtained from models of urinary bladder dysfunction associated with hypertrophy; whether the alteration of atropine-resistant (purinergic) function reported here is a general secondary feature of this type of bladder dysfunction or a change specific to the Semliki Forest Virus model of multiple sclerosis is not resolved. This study provides evidence that peripheral changes as well as central nervous system demyelination occur in the Semliki Forest Virus-infected mouse.