A simple in vivo method for evaluating drug action at central and peripheral synapses.

A simple in vivo method for studying spinal reflexes and neuromuscular transmission in anaesthetized mice is described. The technique utilizes electromyographic recording from muscles of both hind limbs following stimulation of the sciatic nerve in one limb. Drug effects on the neuromuscular junction, on monosynaptic reflex transmission and on crossed polysynaptic reflexes can be assessed. In addition a method for distinguishing between drugs which affect neuromuscular transmission and those which affect nerve conduction is described using their different effects on reexcitation of motoneurons. Details of data collection and analysis using a laboratory microcomputer are presented. The effects of a variety of representative compounds which have been shown to affect central and peripheral neurotransmission in other systems have been evaluated. The actions of these drugs in this system are compared with those obtained using spinal animals and more sophisticated recording techniques. The results compare favourably with those obtained using more complex methods and the technique offers a simple and inexpensive way of evaluating drug action at these synapses.