The effect of postsynaptic deprivation on the presynaptic chief cell in the rat carotid body.

After the surgical removal of the postsynaptic sensory sinus nerve, the presynaptic specializations in the chief cell of the rat carotid body chemoreceptor rapidly disappear. When the sinus nerve is allowed to regenerate, the presynaptic specializations reappear almost simultaneously with the re-establishment of apposition of the nerve to chief cells and the number of the synapses is restored to a normal range by the third week after deafferentation. This finding indicates that the maintenance of the presynaptic specializations in the chief cell depends on the persistence of the postsynaptic element, and further suggest the neurotrophic maintenance of the presynaptic specializations may be exerted by the postsynaptic sinus nerve. The sustentacular cells may play a role in governing the specificity of reinnervation by the sinus nerve.