The new chromogranin-like protein NESP55 is preferentially localized in adrenaline-synthesizing cells of the bovine and rat adrenal medulla

The protein NESP55, a new member of the chromogranin family, is present in large dense-core secretory granules of neuroendocrine tissues. We investiga ted its cellular distribution in adrenal medulla with immunohistochemistry and in situ hybridization. A preferential co-localization of NESP55 with ph enylethanolamine-N-methyltransferase in the adrenergic cell population was found by immunolabelling of consecutive sections. Noradrenergic cells also contained small amounts of NESP55, but the levels as measured by radioimmun oassay were five times lower. The distribution of NESP55 mRNA was similar t o preproenkephalin mRNA which previously was shown to be confined to adrena line-producing cells of the adrenal medulla. The present study indicates th at stimulation of adrenergic cells will release significantly higher amount s of NESP55, The functional implications of this preferential secretion, ho wever, have yet to be discovered. (C) 1999 Elsevier Science Ireland Ltd. Al l rights reserved.