Experimental inhibition of reactive gliotic-like changes in astrocytic cultures

Dibutylcyclic AMP (DiBucAMP) can induce astroblast-containing cultures to form cells which resemble reactive astrocytes observed in vivo. In the present study, myelin- or axolemmal-enriched fractions were assessed for the ability to inhibit (DiBucAMP)-stimulated reactive-like changes in astrocytic cultures. Addition of exogenous myelin- or axolemmal-enriched fractions to DiBcAMP-exposed cultures prevented drug-induced elevation of lactic dehydrogenase (LDH) 2 days after initial addition of the drug and moderated DiBucAMP-induced decreases in the enzyme's activity normally observed 5 days later. The proportion of reactive colonies (i.e., those in which more than 50% of cells are stellate-shape) was significantly lower in cultures exposed to the drug plus myelin or axolemma vs those exposed to DiBucAMP alone. The inhibitory factors in axolemmal fractions were heat sensitive (at 100 degrees C), whereas those in myelin were not. Both fractions were inactivated by trypsin. Whole brain homogenates had no effect on diBucAMP-stimulated changes in culture.