INFLUENCE OF OVARIAN STATUS AND REGIONAL FAT DISTRIBUTION ON PROTEIN-KINASE-C IN RAT FAT-CELLS

The effects of ovarian status on insulin- and phorbol 12-myristate 13- acetate (TPA)-stimulated lipogenic responses, phorbol ester-specific b inding to protein kinase C (PKC) and immunoblot-quantified beta- and e psilon-PKC isoform levels were compared in female rat fat cells from s ubcutaneous and deep intra-abdominal (parametrial) fat deposits. In co ntrol rats, the cytosolic PKC content per cell was 70% lower in subcut aneous than in parametrial adipocytes. In subcutaneous and parametrial fat cells, the cytosolic PKC contents were reduced by ovariectomy and restored to normal by the administration of ovarian hormones (oestrad iol plus progesterone). However, the lipogenic response to TPA was una ltered by ovarian status in both fat deposits, contrasting with the in sulin-stimulated lipogenic response. This response increased in parame trial fat cells after ovariectomy and returned to normal after ovarian hormone treatment whereas, in subcutaneous fat cells, the insulin res ponse was either unaltered by ovariectomy or increased by the administ ration of ovarian hormones. This study shows important site-related di fferences in fat cell PKC content but also reveals a similar modulatio n of this PKC by ovarian status, regardless of the anatomical localiza tion of the fat cells. The physiological significance of these finding s is discussed.