Humpel C, Giacobini M M, Wetmore C, Olson L
Department of Neuroscience, Karolinska Institute, Stockholm, Sweden.
Exp Neurol. 1994 Jun;127(2):171-7. doi: 10.1006/exnr.1994.1092.
Trophic factors are expressed by neurons throughout several areas of the CNS. We studied the mRNA expression of a member of the neurotrophin family, brain-derived neurotrophic factor (BDNF), and of the two receptor transcripts, full-length trkB and truncated trkB in single intraocular cortex cerebri grafts and in double cortex cerebri grafts. All single as well as double intraocular cortex grafts grew well, reaching a maximal size 4 weeks postgrafting. BDNF mRNA was moderately expressed in neurons in all intraocular grafts and significantly increased compared to that in adult rat cortex. Truncated trkB mRNA was strongly expressed in neurons and glia, while full-length trkB mRNA was moderately expressed only in neurons in the intraocular cortical grafts. The expression of the two trkB transcripts in the grafted cortex did not differ from that of adult rat cortex. No difference in the expression of mRNAs for full-length or truncated trkB was found between single grafts grown for 4 or 8 weeks or between single and double grafts. Similarly, no difference in expression of BDNF mRNA in single grafts grown for 4 or 8 weeks was detected. However, BDNF mRNA levels were significantly lower in grafts which were placed in close contact with previously grafted cortex in the eye chamber. Moreover, contact with a second graft led to downregulation of BDNF mRNA in the first graft.(ABSTRACT TRUNCATED AT 250 WORDS)
神经营养因子在中枢神经系统的多个区域由神经元表达。我们研究了神经营养因子家族成员脑源性神经营养因子（BDNF）以及两种受体转录本——全长trkB和截短型trkB在单眼内大脑皮质移植物和双眼内大脑皮质移植物中的mRNA表达。所有单眼和双眼内大脑皮质移植物生长良好，在移植后4周达到最大尺寸。BDNF mRNA在所有眼内移植物的神经元中呈中度表达，与成年大鼠皮质相比显著增加。截短型trkB mRNA在神经元和胶质细胞中强烈表达，而全长trkB mRNA仅在眼内皮质移植物的神经元中呈中度表达。移植皮质中两种trkB转录本的表达与成年大鼠皮质无异。在生长4周或8周的单移植物之间或单移植物与双移植物之间，未发现全长或截短型trkB的mRNA表达存在差异。同样，在生长4周或8周的单移植物中，未检测到BDNF mRNA表达的差异。然而，与眼房内先前移植的皮质紧密接触的移植物中，BDNF mRNA水平显著较低。此外，与第二个移植物接触导致第一个移植物中BDNF mRNA的下调。（摘要截短至250字）
