NEUROIMMUNOLOGICAL REGULATION OF ALPHA-MSH RELEASE IN TILAPIA (OREOCHROMIS-MOSSAMBICUS)

This study describes the effects of IL-1 (interleukin 1) and LPS (bact erial endotoxin lipopolysaccharide) on the release of alpha-MSH (alpha melanocyte stimulating hormone) from the neurointermediate lobe (NIL) of the teleost Oreochromis mossambicus (tilapia). In vivo treatment o f tilapia with IL-1 for 8 days led to a 49% inhibition of basal alpha- MSH release, measured by means of an in vitro micro-superfusion techni que. The treatment did not affect the sensitivity of the tissue to TRH . In vitro, the release of alpha-MSH was inhibited by LPS in a dose de pendent manner. In addition to its effects on the unstimulated release of the hormone, LPS also blunted the response to a TRH stimulation. T ogether with recent results obtained by others demonstrating the effec ts of (neuro-)peptides on immune parameters and the presence of cytoki nes in fish, the present data establish the bidirectional character of the communication between the immune and the (neuro-)endocrine system s in teleosts.