EFFECTS OF DECENTRALIZATION ON THE LEVELS OF GAP-43 AND P38 (SYNAPTOPHYSIN) IN SYMPATHETIC ADRENERGIC-NEURONS - A SEMIQUANTITATIVE STUDY USING IMMUNOFLUORESCENCE AND CONFOCAL LASER-SCANNING MICROSCOPY

The distribution of GAP-43 in superior cervical ganglion (SCG) and iri s were studied in normal animals and following decentralization using immunofluorescence and confocal laser scanning microscopy (CLSM). GAP- 43-like immunoreactivity (LI) was compared with p38 (synaptophysin)-LI , and tyrosin hydroxylase (TH)-LI. In the control SCG, GAP-43-LI and p 38-LI were mainly localized in nerve terminals around the principal ne urons. The neuronal perikarya were negative for GAP-43, but positive f or p38 in a perinuclear zone, as well as positive for TH. SIF cells (S mall Intensely Fluorescent cells, ganglionic interneurons) were positi ve for GAP-43, TH and p38. One day after decentralization, GAP-43-LI a nd p38-LI in nerve terminals around principal neurons had disappeared. Some of the principal neurons showed a weak GAP-43-immunoreactivity. Three days post-decentralization, GAP-43- and p38-positive nerve termi nals around the neurons had reappeared in considerable numbers and the intra-ganglionic nerve bundles were positive for both antibodies. In the control irides, GAP-43-LI and p38-LI were distributed in a varicos e pattern in the nerve bundles, around blood vessels and in the networ k of terminals. Double labelling studies showed that GAP-43-LI was col ocalized with TH-LI and p38-LI. The network of terminals in the dilato r plate of the irides was quantified by measuring the fluorescence int ensity of randomly selected areas, using CLSM. Three days after decent ralization the intensity of GAP-43-LI and p38-LI had significantly inc reased. TH-LI had decreased 8 days after decentralization. The results indicate that GAP-43-LI and p38-LI are normally present in the nerve fibers and terminals of both pre- and post-ganglionic neurons in adult rats. The expression of GAP-43-LI and p38-LI in post-ganglionic neuro ns is preganglionically regulated, as indicated by the increased expre ssion after decentralization. The expression of p38 in these neurons i s probably regulated via mechanisms that are separate from those which regulate GAP-43, since it showed a different time course than that of GAP-43-LI.