Regional differences in responsiveness of adult CNS axons to grafts of cells expressing XXXX @entity19562 .

@entity1 @entity19563 @entity19562 @entity14840 @entity1573 @entity2252 @entity35
@entity19562 ( @entity19562 ) belongs to the neurotrophin family, which also includes nerve growth factor, @entity2252 , and @entity19563 /5. @entity19562 mRNA is widely expressed in the rodent nervous system, but the physiological function of the native protein is still unclear. Genetically modified cell lines that produce physiological amounts of @entity19562 can provide a useful tool in the elucidation of the @entity19562 effects in the adult central nervous system (CNS). Genetically modified @entity35 primary skin fibroblasts expressing and secreting @entity1 @entity19562 ( @entity14840 ) were prepared and characterized. In vitro, cell lines derived from different retroviral constructs expressed @entity14840 mRNA, as determined by PCR and RNA blot analysis. Secretion of biologically active @entity14840 was confirmed by specific elicitation of neurite outgrowth from cultured @entity1573 primary sympathetic and sensory neurons and from @entity35 fetal locus coeruleus neurons in the presence of @entity14840 -producing cell conditioned media. In vivo, implanted fibroblasts survived well up to the maximal experimental time points of 6 weeks (brain) and 4 weeks (spinal cord) and continued to express @entity14840 mRNA in vivo. As early as 2 weeks postgrafting, specific sprouting of host sensory neurites in response to @entity14840 -producing grafts was observed in the spinal cord. In contrast, @entity14840 -producing cerebral grafts did not induce a sprouting response different from that observed with control grafts. These findings establish the existence of a regionally different responsiveness of the CNS axons to local @entity14840 overexpression.
