A Study on NSE and NNE mRNA Expression in Rat Pineal Gland : in Situ Hybridization Analysis

The expression of neuron-specific enolase（NSE）and non-neuronal enolase（NNE）mRNA in the postnatal developing and adult rat pineal glands was examined by in situ hybridization and analysed in connection with the findings of synaptophysin（SYN）immunostainings. At day 0, SYN immunopositivity was observed in about 50% of pineal gland cells, while it was negative in the remaining cells which formed cord-like structures. Subsequently, the SYN positive cells were gradually increased and the SYN negative cord-like structures seemed to be fragmented by them. At day 10 or later, the SYN immunopositivity was observed in more than 90% of pineal cells as in adult stage, and the SYN immunonegative cord-like structures became negligeble. In in situ hybridization, throughout the postnatal developmental and adult stages, NSE signals were mainly localized in SYN positive areas, while NNE signals were seen in both SYN positive and, though less intensely, SYN negative areas as well. During the first 10 days, both NSE and NNE signals increased gradually in SYN positive areas showing 2-3 fold NNE predominancy and reached the adult levels at day 10. Although, unlike NNE signals, NSE signals were usually unclear in the SYN negative cord-like structures at day 0-10, distinct NSE signal were detected in some of the constituent cells, suggesting that the cord-like structures contained the progenitor cells for pineocytes.