Changes in rat retinal ganglion neuronotrophic factor and its mRNA during postnatal development.

The monoclonal antibody specific to the retinal ganglion neuronotrophic factor (RGNTF) was used to localize and quantify the presence and amount of RGNTF during the postnatal development of the visual system in the rat. The results showed that in the 0-1-day age group, neurons at the superficial layers and deep part of superior colliculus, and as well as retinal ganglion cells were strongly stained with their RGNTF contents quantified to be 88%, 100% and 100%, respectively. In the 5-6-day age group, RGNTF contents were significantly reduced to merely 50%, 30% and 80%, respectively. The RGNTF contents reduced further to 0% as age increased to 2 years old. A 32P-DNA probe specific to the first 7 amino acid sequence of RGNTF at its N-terminal end was synthesized and used for in situ hybridization studies. The results revealed that strong hybridized signals (i.e. mRNA of RGNTF) were localized in the same neurons in the superficial layers and deep part of the superior colliculus only in the 0-1-day age group, and that no signals were found in retinae of all postnatal age groups. The significant reduction of RGNTF may be related to the RGC death during postnatal development. Neurons at the superficial layers and deep part of the superior colliculus are the sources of RGNTF for RGCs in the postnatal retina.