Alpha motor neurons release GABA

Renshaw cell

after the discoverer Birdsey Renshaw (1911-1948)
English: renshaw cell

1 definition

Renshaw cells are inhibitory interneurons of the spinal cord that project onto alpha motor neurons.

2 anatomy

Renshaw cells are in close proximity to the alpha motor neurons of the anterior horn of the spinal cord (Cornu anterius medullae spinalis). You will receive inputs from:

3 physiology

The Renshaw cells are activated cholinergically. Using inhibitory neurotransmitters glycine and gamma-aminobutyric acid (GABA), they generate an inhibitory postsynaptic potential (IPSP) within the alpha motor neurons. As multipolar nerve cells, alpha motor neurons have a large number of other inputs (neuronal convergence). The result of their activity results from the summation of various inputs (EPSPs and IPSPs). Renshaw cells thus have an inhibitory, but more modulating, influence on the motor activity of the motor neurons.

3.1 Renshaw escapement

The inhibitory effect of the Renshaw cells is called Renshaw inhibition. The Renshaw inhibition prevents excessive muscle contractions as a reflex response of the muscle reflex.

In the sense of a negative feedback mechanism, alpha motor neurons project cholinergic via axon collateral onto Renshaw cells, which they themselves inhibit. This process is called reverse inhibition or recurrent inhibition.

see also: neuronal inhibition

4 clinic

A pathological disorder of the Renshaw inhibition occurs when the wound is infected with Clostridium tetani. Its bacterial toxin (tetanus toxin) reaches the spinal cord via peripheral nerves by means of retrogradaxonal transport and hematogenously. There it prevents the release of the inhibitory neurotransmitters from the Renshaw cells. The failure of the Renshaw inhibition leads to an initial hyperreflexia. In the further course, the permanent activation of the alpha motor neurons leads to a fusion of the individual muscular twitches into permanent contractions (spasticity) with the typical tetanus signs (risus sardonicus, opisthotonus, tonic-clonic seizures).

see also: Tetanus, tetanus toxin