Differential expression of peroxisome proliferator-activated receptor-α, -β, and -γ during rat embryonic development

The expression patterns of the three different peroxisome proliferator-activated receptor (PPAR) isotypes have been determined during rat embryonic development by in situ hybridization. The expression of PPAR alpha starts late in development, with increasing levels in organs such as liver, kidney, intestine, and pancreas, in which it will also be present later in adulthood to regulate its specific target genes. PPAR alpha is also transiently expressed in the embryonic epidermis and central nervous system. PPAR gamma presents a very restricted pattern of expression, being strongly expressed in brown adipose tissue, in which differentiation it has been shown to participate. Like PPAR alpha, it is also expressed transiently in the central nervous system. Interestingly, PPAR alpha, -beta and -gamma are coexpressed at high levels in brown adipose tissue. Finally, the high and ubiquitous expression of PPAR beta suggests some fundamental role(s) that this receptor might play throughout development.