STRONG INDUCTION OF ACTIVIN EXPRESSION AFTER HIPPOCAMPAL LESION

WE studied the temporal and spatial mRNA expression pattern of activin /inhibin beta(A), beta(B) and alpha subunits after unilateral kainic a cid lesions of the hippocampal CA3 region. We found a strikingly incre ased expression of beta(A) mRNA in the ipsilateral hippocampus 6-24 h after injury. By contrast, the beta(B) and alpha mRNAs were expressed at equally low levels in normal and injured hippocampi, suggesting tha t the beta(A) transcripts give rise to activin A, but not to activin A B or inhibin. In situ hybridization demonstrated the presence of beta( A) mRNA in neurones near the site of lesion. Expression of all known t ypes of activin receptors could be demonstrated in normal and injured hippocampi by RT-PCR. These findings suggest a role of activin in brai n injury.