BIOCHEMICAL AND ANATOMICAL ANALYSIS OF CHOLINERGIC, NORADRENERGIC ANDSEROTONERGIC INNERVATION OF FETAL NEOCORTICAL TRANSPLANTS PLACED IN EXCITOTOXIN-INDUCED NEOCORTICAL LESIONS OF ADULT-RATS

Fetal neocortical block transplants were implanted into the excitotoxi cally ablated sensorimotor cortex of adult rats in order to examine th e density of innervation and distribution of presumptive host derived afferent fibers within these transplants. Cholinergic fiber innervatio n was examined at 3 months post grafting by measuring acetylcholineste rase (AChE) and choline acetyltransferase (ChAT) enzyme activities wit hin the grafts and within the corresponding host cortex by radiochemic al enzyme assays as well as by AChE histochemistry for the visualizati on of AChE positive fibers. Noradrenergic and serotonergic inputs were examined by high performance liquid chromatography (HPLC) measurement s of noradrenaline (NA) and serotonin (5-hydroxytryptamine, 5-HT) conc entrations as well as by tyrosine hydroxylase (TH) and 5-HT immunocyto chemistry for the visualization of monoaminergic fiber distribution. O ur results demonstrated that the grafts contained significantly lower levels of neurotransmitter markers when compared to normal unablated c ortex. The anatomical analysis showed an unequal fiber distribution wi thin the transplants. Areas adjacent to the host tissue revealed a rel atively dense fiber innervation when compared to the density observed within the more central parts of the transplants, and the anatomical d ata therefore supported the biochemical data in suggesting an overall lower cholinergic and monoaminergic innervation of fetal neocortical t ransplants placed into the lesioned adult cortex when compared to norm al cortex.