INCREASED EXPRESSION OF GALANIN IN THE RAT SUPERIOR CERVICAL-GANGLIONAFTER PREGANGLIONIC AND POSTGANGLIONIC NERVE LESIONS

Using immunohistochemistry the expression of galanin (GAL) and galanin message-associated peptide (GMAP) in the superior cervical ganglion ( SCG) was investigated 2, 4, 7, and 14 days after unilateral transectio n of the cervical sympathetic trunk (decentralization) or after cuttin g the external and internal carotid nerves (axotomy), as well as 7 day s after removal of parotid gland tissue. In control SCGs including the sympathetic trunk and the carotid nerves, very few neurons and fibers were GAL/GMAP-positive. Two and 7 days after decentralization, about 5% of all counted neuron profiles in the ipsilateral SCG; were GAL/GMA P immunoreactive. Immunoreactive cell bodies were distributed througho ut the SCG, with a greater number in the most caudal portion of the ga nglion. Many GAL/GMAP-positive nerve fibers were observed in the whole SCG, with strongly fluorescent bundles of immunoreactive fibers accum ulated at the caudal end of the SCG. Several GAL/GMAP-immunoreactive n erve fibers were seen ipsilaterally in the external carotid nerve, whe reas only a few positive fibers could be observed in the internal caro tid nerve. About 2% of all counted neuron profiles in SCGs ipsilateral to decentralization still contained GAL/GMAP-immunoreactivity 14 days after the operation. The number of GAL/GMAP-positive cell bodies was at least doubled in the contralateral SCGs after decentralization comp ared to controls. After axotomy, about 50% of all counted neuron profi les were GAL/GMAP-positive in the ipsilateral SCG and distributed thro ughout the SCG. A strong accumulation of immunoreactive nerve fibers w as observed in both the internal and external carotid nerves. The numb er of GAL/GMAP-positive cell bodies was slightly increased in the cont ralateral SCGs. After unilateral removal of parotid gland tissue, many GAL/GMAP-positive cell bodies and some fibers were observed in the ca udal half of the ipsilateral SCG. The number of immunoreactive nerve f ibers was increased also in the external carotid nerve, but not in the internal carotid nerve. In situ hybridization revealed prepro GAL mRN A in about 5% of all SCG neuron profiles in decentralized SCGs, parall eling the increase seen in GAL/GMAP peptide content. There was also a small increase in prepro VIP mRNA-positive cells in the caudal part of the SCG. The present results indicate that both pre- and postganglion ic lesions increase the content of GAL/GMAP in the SCG, with a much mo re pronounced increase after transection of the carotid nerves, (C) 19 94 Academic Press, Inc.