CHOLINERGIC TRANSMISSION IN THE HYPOGLOSSAL REINNERVATED NICTITATING MEMBRANE OF THE CAT: AN ENZYMATIC, HISTOCHEMICAL AND PHYSIOLOGICAL STUDY

¹ Departments of Phauinacology and Histology, Karolinska Institute, Stockholm, Sweden

Cross-anastomosis of the hypoglossal nerve to the nictitating membrane of the cat results ill a functional cholinergic reinnervation of this organ. Monoamine-containing fluorescent fibers are iio longer seen to innervate the musculature of the membrane and there is a significant decrease in the monoamine oxidase activity. These changes indicate loss of the normally present sympathetic adrenergic innervation. The reinnervated nictitating membrane instead contains cholineacetvlase. In addition, some nerve fibers stain positively for cholinesterase. The contraction in response to electrical stimulation is blocked by atropine. These results support the view that a functional cholinergic innervation of the membrane is established in the absence of any detectable adrenergic innervation as a consequence of the heterogeneous anastomosis of the nictitating membrane with a cholinergic nerve.