TISSUE-SPECIFIC REGULATION OF FAT-CELL LIPOLYSIS BY NPY IN 6-OHDA-TREATED RATS

The effects of neuropeptide Y (NPY), peptide YY (PW), [Leu(31), Pro(34 )]NPY, and NPY(13-36) on adipocyte lipolysis have been studied in subc utaneous (inguinal) and visceral (parametrial) rat adipose tissues. A 48-h fasting period and chemical sympathectomy were used to evaluate t he regulation of Y1 and Y2 pathways in rat adipocytes. NPY, PYY, and [ Leu(31), Pro(34)] NPY significantly inhibited fat cell lipolysis by ab out 25% in both tissues (p less than or equal to 0.05). This inhibitio n was achieved mainly through the Y1 pathway. No significant response to NPY(13-36) was observed, suggesting a lack of involvement of the Y2 pathway in the antilipolytic effect of NPY and PW. The 48-h fasting p eriod led to the loss of the Y1 inhibitory effect previously observed in control rats. On the other hand, the chemical sympathectomy induced a 35% increase of fat cell lipolysis (p less than or equal to 0.05). The latter involved the Y2 pathway as stimulated by NPY(13-36), and wa s observed in the parametrial tissue exclusively. These results sugges t that: a) rat Y receptors reported to exhibit Gi responses can also e xpress Gs-like responses, and b) visceral and subcutaneous adipose tis sues exhibit specific regulation of fat cell lipolysis. (C) 1997 Elsev ier Science Inc.