Peptide YY (PYY) and fish pancreatic peptide Y (PY) expression in the brain of the sea bass (Dicentrarchus labrax) as revealed by in situ hybridization

Tetrapod vertebrates express three neuropeptide Y (NPY)-related peptides: N PY, peptide YY (PW), and pancreatic polypeptide (PP). Both NPY and PYY mRNA have been localized in the brain of tetrapods whereas PP expression is res tricted to the pancreas. Some teleost fish commonly produce NPY and PW but pancreatic peptide Y (PY) instead of PP. Both NPY and PW mRNAs are widely d istributed in the brain of non-tetrapod species, but no information about P Y central expression is available. In the present study, molecular riboprob es were used to study PW and PY mRNA central distribution in the sea bass ( Dicentrarchus labrax). PYY and PY gene expression was predominantly detecte d within the sea bass forebrain. Telencephalic PW gene expression was restr icted to the ventral part of the ventral telencephalon, and no PY expressio n was detected in the cerebral hemispheres. Both PW and PY mRNAs were found within the preoptic area and lateral hypothalamus. Distinct PY or PW mRNA cell groups were localized in the pretectal area and synencephalon or poste rior tubercle, respectively. Caudally, PY gene expression was found in the medial reticular formation, whereas PYY transcripts were localized within t he vagal lobe. The results demonstrate that vertebrate brain expresses thre e NPY-related genes and further support the hypothesis that PP and PY arose by independent gene duplications from PW. The receptor system of the NPY f amily as well as gene expression within the main hypophysiotropic and feedi ng behavior areas suggest an involvement of both peptides in the control of food intake and pituitary secretion. (C) 2000 Wiley-Liss, Inc.