Serotonin regulation of nerve growth factor synthesis in neonatal and adult astrocytes: Comparison to the beta-adrenergic agonist isoproterenol

Although serotonin regulates synthesis of the neurotrophic factor S-100 bet a by astrocytes, its ability to affect nerve growth factor (NGF) synthesis has never been examined. We report here that there is a correlation between the effect of serotonin on cyclic adenosine monophosphate (cAMP) content a nd on NGF content in neonatal astrocytes but not in adult astrocytes. In ne onatal striatal astrocytes, serotonin increases both cAMP and NGF, whereas, in neonatal cerebellar astrocytes, serotonin decreases both. The increase in neonatal cortical astrocyte cAMP appeared to be too small (45%) to incre ase NGF significantly. The P-adrenergic agonist isoproterenol increased cAM P and NGF in both cortical and striatal astrocytes derived from neonatal ra ts. In contrast, there was a dissociation between cAMP changes and NGF chan ges in astrocytes derived from adult rats. Both serotonin and isoproterenol increased cAMP in adult cortical astrocytes, without any effect on NGF con tent. However, adult striatal astrocytes responded to serotonin with an ele vation of both cAMP and NGF, whereas isoproterenol could only enhance cAMP, without affecting NGF. Thus, in neonatal astrocytes, a change of sufficien t magnitude in cAMP was correlated with a comparable change in NGF, in resp onse to activation of either serotonergic or P-adrenergic receptors; in cer ebellar astrocytes, the decrease in cAMP was accompanied by a decrease in N GF. in contrast, adult astrocytes were not responsive: Although cAMP change s were large, NGF synthesis was increased only in striatal astrocytes and o nly in response to serotonin. Published 2001 Wiley-Liss, Inc.