Expression of peroxisome proliferator-activated receptor gamma (PPAR gamma) in normal human pancreatic islet cells

Aims/hypothesis. Thiazolidinediones are reported to improve pancreatic isle t morphology and beta-cell function in rodents, supporting the hypothesis o f a direct action of thiazolidinediones on endocrine islet cells. In this s tudy we examined the expression of the peroxisome proliferator-activated re ceptor gamma, a nuclear receptor that is activated by naturally occurring f atty acids and synthetic thiazolidinediones, in normal human endocrine panc reatic cells. Methods. Human islets were isolated from pancreata harvested in ten brain-d ead lean non-diabetic adult donors. We analysed the gene and protein expres sion of the human peroxisome proliferator-activated receptor gamma and eval uated the effects of peroxisome proliferator-activated receptor gamma agoni st on insulin secretion in human islet preparations, Results. The RT-PCR carried out on total RNA from four distinct human islet preparations demonstrated the presence of peroxisome proliferator-activate d receptor gamma mRNA. Western blot analysis showed the consistent expressi on of peroxisome proliferator-activated receptor gamma protein. Peroxisome proliferator-activated receptor gamma was shown to be present in all three endocrine cell types studied (alpha, beta and delta cells) by immunohistoch emistry. Conclusion/interpretation. We found that peroxisome proliferator-activated receptor gamma is highly expressed in human islet endocrine cells, both at the mRNA and protein levels. These results support the hypothesis of a dire ct influence of peroxisome proliferator-activated receptor gamma agonist on human pancreatic endocrine cells.