NONADRENERGIC, NONCHOLINERGIC NEURONS INNERVATING THE GUINEA-PIG TRACHEA ARE LOCATED IN THE ESOPHAGUS - EVIDENCE FROM RETROGRADE NEURONAL TRACING

The possibility that non-adrenergic, non-cholinergic (NANC) neurons in nervating the guinea-pig trachea may be located within the oesophagus has been investigated using an in vitro retrograde tracing technique. The cervical trachea and oesophagus were excised from guinea-pigs and DiI was applied to a 5 mm region of the trachealis muscle. These prepa rations were maintained in organotypic culture for 3 days and processe d for immunohistochemistry. A mean of 44 (4 neural cell bodies in the oesophageal myenteric plexus were found to be labelled by DiI. The vas t majority of these neurons contained nitric oxide synthase, vasoactiv e intestinal polypeptide and neuropeptide Y. It is suggested that the population of neurons identified in this study are postganglionic para sympathetic neurons mediating NANC relaxation of the trachealis muscle in this species. (C) 1998 Elsevier Science Ireland Ltd.