Enkephalin precursor gene expression in postmeiotic germ cells.

Preproenkephalin mRNA was detected in rat testis after postnatal day 30. A high abundance of preproenkephalin mRNA was present in the spermatids (i.e., spermatogenic cells at postmeiotic stage) purified from mature rat testis. The mRNA size of the spermatids was about 1900 bases, which was larger than that of other tissues expressing the preproenkephalin gene. The spermatids contained small amounts of enkephalin-containing proteins, but little or no Met-enkephalin. Preproenkephalin gene expression in the germ cells suggests the connection between gametogenesis and nervous system.