ABSTRACT
This chapter presents a detailed mapping of the termination sites of aortic and carotid baroreceptor and carotid chemoreceptor afferent fibers in the nucleus tractus solitaries complex of the rat. It summarizes neuroanatomical data obtained in our laboratory regarding the distribution of primary baroreceptor and chemoreceptor afferent fibers in the medulla of the rat. The central projections of the arterial receptors were identified by using the sensitive anterograde transganglionic tract tracer cholera-toxin conjugated horseradish peroxidase, in combination with the tetramethyl benzidine histochemical method. The two most likely candidates for neurotransmitters of the primary baroreceptor and chemoreceptor afferent fibers are l-glutamate and substance P (subP). SubP immunoreactive cell bodies and fibers have been immunohistochemically localized within the petrosal and nodose ganglia. These fibers continued through the dorsal medullary reticular field and appeared to terminate in and around the dorsal aspect of the nucleus retroambiguus.
