ABSTRACT
This chapter describes the distribution of nerve fibers to sensory organs with particular reference to the presence of neuropeptides. There is increasing evidence that perivascular nerve fibers of sympathetic, parasympathetic, and sensory nature contain peptides, and that such neuropeptides serve as important regulators of local blood flow. The neuropeptides probably function within the confines of the sympathetic, parasympathetic, and sensory nervous systems. The lack of specific neuropeptide antagonists, however, makes an assessment of their precise functional significance difficult. In addition to classical transmitters, several neuropeptides have been demonstrated in perivascular nerve fibers and it is not inconceivable that such peptides may play important roles as regulators of the regional blood flow. Extirpation of the cervical sympathetic ganglia eliminated the perivascular adrenergic nerve fibers in the inner ear. Substance P and calcitonin gene-related peptide probably coexist in the perivascular nerve fibers in the nasal mucosa.
