BIOSYNTHESIS OF CARNOSINE IN PRIMARY CULTURES OF RAT OLFACTORY-BULB

Primary cultures of glia cells obtained from adult rat olfactory bulb synthesize carnosine (beta-alanyl histidine). The rate of synthesis in creases the older the culture is and is enhanced by the addition of di butyrylcyclic-AMP (dBcAMP) to the medium. Millimolar concentrations of this agent intensify galactocerebroside (GalC) staining compared to c ontrol cultures. Removal of GalC positive cells through antibody and c omplement cell killing decreases carnosine synthesis to a minimum. Cul tures prepared from olfactory bulb of new-born rats contain neuron spe cific enolase (NSE) positive neurons and GalC positive ensheathing cel ls. Such cultures produce carnosine. When switched to nerve growth fac tor (NGF) depleted medium containing dBcAMP the share of neurons in th e culture decreases drastically with time and concomitantly an increas e of the relative rate of carnosine synthesis is observed. After 1 wee k in such medium the cultures contain almost no NSE positive cells. Vi rtually all cells express glial fibrillary acidic protein (GFAP) and a re GalC positive. These data suggest that carnosine is synthesized by the ensheathing cells of the olfactory bulb and not by olfactory neuro ns. (C) 1997 Elsevier Science Ireland Ltd.