ABSTRACT
Objective To investigate the impact of polyclonal neural cell adhesion molecule antibody (P-NCAM-Ab) on the potency of botulinum toxin A (BTX-A).Methods Ninety male Sprague-Dawley rats were randomly divided into 3 equal groups:a normal control group,a BTX-A group and a P-NCAM-Ab group.The rats in the normal control group were injected with 100 μl of saline solution in their right gastrocnemius,while those in the BTX-A and P-NCAM-Ab groups were injected with 100 μl of BTX-A (0.5 U).In addition,the rats in the P-NCAM-Ab group were also injected with 100 μl of P-NCAM-Ab (the dosage was 20 U) at the same site on the 3rd day after the BTX-A injection.The rats' gastrocnemius muscle strength was evaluated with a self-made system for evaluating neuromuscular function before and after the toxin injection,on the 3rd day,as well as 1,2,4,6,8,10 and 12 weeks after the BTX-A injection.Any wet weight changes in the muscles were observed,and immunochemistry methods were employed to observe any structural changes in the motor endplates and nerve fibers at the different time points.Results After the saline injection,the average gastrocnemius muscle strength of the control group increased with time,while strength in the BTX-A and P-NCAM-Ab groups demonstrated a decrease in strength followed by a gradual increase.The average gastrocnemius muscle strength of the rats in the BTX-A and P-NCAM-Ab groups was significantly lower than that of the control group at all time points.Compared with the BTX-A group,the muscle strength of the P-NCAM-Ab group rats decreased further.Strength recovery in the BTX-A and P-NCAM-Ab groups was significantly slower than in the control group.The wet weight percentage in the BTX-A and P-NCAM-Ab groups at first decreased and then recovered with time.After the BTX-A injection,the average wet weight percentage of the P-NCAM-Ab group rats was significantly lower than that of the BTX-A group after 3 days,and 1,2 and 4 weeks.Karnovsky-Roots AchE staining showed that the motor endplates' color in the BTX-A and P-NCAM-Ab groups deepened gradually,though the color of the P-NCAM-Ab group was lighter than that of the BTX-A group at each time point.The mean optical density of the motor endplates' positive reaction area increased with time in both groups,but the P-NCAM-Ab group was lower than that of the BTX-A group at 1,2,4,8 and 12 weeks.Counting the nerve fibers dyed by gold chloride showed similar trends with both experimental groups significantly different from the control group.Conclusion P-NCAM-Ab can increase the potency of BTX-A and prolong its action.
ABSTRACT
Objective To develop a method for dynamically observing the biological efficacy of botulinum toxin A (BTX-A) and to investigate the dose-effect relationship between BTX-A dosage and muscle strength.MethodsFifty-four male Sprague Dawley rats were randomly divided into 9 groups.Groups 1-7 were injected intramuscularly with 0.1 ml BTX-A (0.01 U to 4.0 U) into the gastrocnemius on the right side.Rats in group 8 were injected intramuscularly with an equal volume of saline solution as the control group,and group 9 was used to determine the location of injection.Gastrocnemius muscle strength was evaluated using a self-made evaluation system before and after the toxin injection and on the 3rd,7th,14th,21st,30th,45th,60th and 75th day following.ResultsMuscle strength reached its lowest level on days 3 to 7,with a significant difference in the decline of muscle strength between the test groups and the control group up to day 60.With the lower BTX-A doses (0.01 U,0.1 U,0.5 U,1.0 U),muscle strength had decreased significantly on the 21st day,but recovered to its initial levels in all groups at the same time.There was no significant difference among the 1.0 U,1.5 U,2.0 U and 4.0 U groups.ConclusionsStandardized gastrocnemius injection combined with neuromuscular functional evaluation can establish a model of BTX-A dosage and muscle paralysis which can be used to assess the evolution of the biological efficacy of BTX-A.