NEUROTRANSMITTER AND AMINO-ACID-ANALYSIS AND ULTRASTRUCTURAL OBSERVATIONS OF FETAL BRAIN CORTEX TRANSPLANTATION TO ADULT-RAT BRAIN UNDER THE EFFECT OF DEXAMETHASONE

OBJECTIVE: To conduct an investigation of fetal cortical tissue graft survival using transmission electron microscopy and analyzing neurotra nsmitters and amino acids and their function, with special reference t o the effect of dexamethasone. METHODS: Transplantation of fetal corti cal brain tissue to 100 adult Wistar albino rats weighing 170 to 220 g was performed. The rats were divided into three groups. Only transpla ntation of fetal cortical brain tissue was performed in the first grou p (n = 36). In the second group (n = 48), dexamethasone was administer ed in addition to fetal cortical tissue transplantation. The third gro up (n = 16) was used as the surgical control group. The rats were allo wed to live for 6 weeks and were then decapitated. The grafts were exa mined by electron microscopy. Additionally, quantitative analyses of t he neurotransmitters and amino acids of the grafts were conducted usin g high-pressure liquid chromatography. RESULTS: Electron microscopic o bservations revealed that the grafts were still surviving at the end o f the 6th week in both groups. However, in the group that received dex amethasone, neurons and their organelles were better developed than in the group that did not receive dexamethasone, Concommitantly, results of quantitative analysis in the dexamethasone group revealed statisti cally extremely significant higher amino acid values for glutamic acid , aspartic acid, beta-alanine, and lysine and significantly higher val ues for gamma-aminobutyric acid, glutamine, glycine, and serine when c ompared to the nondexamethasone group. CONCLUSION: Dexamethasone is ef fective in increasing the survival and in developing the ultrastructur al and functional outcome of transplanted neurons in fetal grafts.