Comparison between the effects of botulinum toxin-induced paralysis and denervation on molecular forms of acetylcholinesterase in muscles.

Velocity sedimentation analysis of acetylcholinesterase (AChE) molecular forms in the fast extensor digitorum longus muscle and in the slow soleus muscle of the rat was carried out on days 4, 8, and 14 after induction of muscle paralysis by botulinum toxin type A (BoTx). The results were compared with those observed after muscle denervation. In addition, the ability of BoTx-paralyzed muscles to resynthesize AChE was studied after irreversible inhibition of the preexistent enzyme by diisopropyl phosphorofluoridate.

The effects of pretreatment with soman simulator in the skeletal muscle: direct interactions with acetylcholinesterase.

Soman simulator PDP is a compound that has a chemical structure identical to soman, except that the fluorine atom is replaced by a methyl group which makes PDP unable to bind covalently to the AChE active center. In rats, late mortality observed after treatment with high doses of soman could be prevented by PDP pretreatment. Such pretreatment has been much less efficient in primates.

Influence of denervation on the molecular forms of junctional and extrajunctional acetylcholinesterase in fast and slow muscles of the rat.

Acetylcholinesterase (AChE) molecular forms in denervated rat muscles, as revealed by velocity sedimentation in sucrose gradients, were examined from three aspects: possible differences between fast and slow muscles, response of junctional vs extrajunctional AChE, and early vs late effects of denervation. In the junctional region, the response of the asymmetric AChE forms to denervation is similar in fast extensor digitorum longus (EDL) and slow soleus (SOL) muscle: (a) specific activity of the A12 form decreases rapidly but some persists throughout and even increases after a few weeks; (b) an early and transient increase of the A4 AChE form lasting for a few weeks may be due to a block in the synthetic process of the A12 form. In the extrajunctional regions, major differences with regard to AChE regulation exist already between the normal EDL and SOL muscle.

Biochemical, morphological, and functional changes during peripheral nerve regeneration.

The success of axon regeneration after nerve injury should be judged by the extent to which the target organs regain their function. Recovery of muscle contraction involves axon regeneration, reestablishment of nerve-muscle connections, recovery of transmission, and muscle force. All these processes were investigated under the same experimental conditions and correlated in order to better understand their time-course and interdependence.

Influence of innervation on molecular forms of acetylcholinesterase in regenerating fast and slow skeletal muscles.

Nerve-intact muscle regenerates were prepared by ischemic-toxic injury of slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles of the rat. Rapid innervation of regenerating myotubes modified intrinsic patterns of AChE molecular forms, revealed by velocity sedimentation in linear sucrose gradients. Regarding their onset, the effects of innervation can be classified as early and late.