Transforming growth factor beta2 is able to modify mRNA levels and release of luteinizing hormone-releasing hormone in a immortalized hypothalamic cell line (GT1-1)

On the basis of our previous observations which indicated that transforming growth factor beta1 (TGFbeta1) affects the gene expression and the release of luteinizing hormone-releasing hormone (LHRH) in GT1-1 cells, we have presently evaluated whether also TGFbeta2 might be effective on these parameters. The data here reported show that also TGFbeta2 is able to affect LHRH dynamics, and that this action presents a different kinetics than that reported by TGFbeta1. In particular TGFbeta2 is able to facilitate LHRH release and to decrease the mRNA levels of this decapeptide. The present data have also shown that, GT1-1 cells express the messengers for the two most important receptors of the TGFbeta family, namely TGFbetaRI and TGFbetaRII and consequently represent a target for the action of the different isoforms of TGFbeta. Since the two isoforms of TGFbeta are produced and released from astrocytes, the present data add new support to the hypothesis that astrocytes participate in the control of LHRH secretion in a paracrine fashion.