| Popis: |
Recent advances in the treatment of organophosphorus (OP) toxicity have focussed on the administration of an exogenous cholinesterase (ChE) to act as a scavanger for the OP agent (Doctor, et al., 1991). As compared with treatment therapies that involve counteracting the effects of increased cholinergic activity following OP exposure (e. g., atropine), the method offers the advantage of neutralizing the OP before target organs are affected. Since maximum efficacy is achieved when the exogenous ChE is administered prior to OP exposure, possible deficits in performance produced by ChE administration alone is an important consideration. We have previously demonstrated that, in contrast to physostigmine or atropine (Genovese, et al., 1990), administration of horse serum butyrlcholinesterase (HS-BChE) fails to disrupt performance of rats on an operant conditioning task (Genovese, et al., 1993). The present study further investigated the possibility that HS-BChE might produce deficits in performance. Specifically, we assessed the effects of HS-BChE, in rats, on spontaneous motor activity and on a passive avoidance memory task. Motor activity was monitered continuously by using photo-emitter / detector pairs mounted in the home cages of the rats. A 12h:12h light:dark cycle was maintained and activity counts (i. e., consecutive photobeam breaks) were collected in 5-min intervals. Under baseline conditions, approximately 80%, or more, of the total daily activity occurred during the dark period, demonstrating a typical circadian pattern of activity. Two groups of rats were injected (IP) with either HS-BChE (7500U, n = 4) or vehicle (n = 4), and motor activity was monitered for 10 consecutive days. No statistically significant differences were observed between groups for measures of total daily activity or the circadian pattern of activity. Comparisons between pre- and post-injection measures of activity were also not significantly different for either group. |
