[Noradrenaline synthesis by locus coeruleus neurons transplanted in rat frontal cortex--influence of denervation of intrinsic noradrenergic projection].

Locus coeruleus (LC) noradrenergic neurons obtained from rat embryo (embryonic day 17) was prepared as cell suspension, and this neuronal cell suspension was transplanted in the frontal cortex of adult rats. The recipient rats were divided into 2 groups to examine the influence of the elimination of the intrinsic noradrenergic projection to the cortex on the transplanted neurons: the first group of animals received electric LC lesion 1 week prior to the transplantation (pre-lesioned group), and the second group received LC lesion 5 weeks after the transplantation (post-lesioned group). The animals were sacrificed 8 weeks after the transplantation, and the noradrenaline (NA) content in the frontal cortex was measured. The NA content in the frontal cortex was also measured 3 or 8 weeks after the LC lesion in the rats received no transplantation (without-T group). The NA content in the frontal cortex was 249 +/- 69 ng/g tissue weight (mean +/- SD, n = 7) in the pre-lesioned group and 252 +/- 69 (n = 11) in the post-lesioned group, while the NA content in the without-T group remained as low as 61 +/- 44 (n = 5) 3 weeks or 51 +/- 14 (n = 9) 8 weeks after the LC lesion. The differences of the NA content between the without-T group and the other two groups were statistically significant respectively. These results suggested that, both in the pre- and post-lesioned groups, the transplanted neurons survived in the recipient animal and synthesized substantial amount of specific neurotransmitter or NA.(ABSTRACT TRUNCATED AT 250 WORDS)