Strychnine Poisoning

The importance of inhibitory neurons can be appreciated by observing what happens when normal inhibition is blocked.

Normally, inhibitory neurons in the spinal cord called Renshaw cells release glycine at inhibitory synapses with motor neurons that cause contraction of skeletal muscle fibers. This inhibitory input prevents excessive muscular contraction. Strychnine binds to and blocks glycine receptors and causes massive tetanic contactions. 

All skeletal muscles, including the diaphragm, contract fully and remain contracted. 

Because the diaphragm cannot relax, the person cannot breathe. The normal delicate balance between excitation and inhibition in the CNS in disturbed and motor neurons are firing without restraint.