Table 1.

Tissue distributions of the various PPARs (RNA and protein) in adult rodents and humans. Abbreviations: GI, gastrointestinal; WAT, white adipose tissue; BAT, brown adipose tissue; CNS, central nervous system. Symbols: −, absent; ±, barely detectable; +, weak; ++, moderate; +++, high; ++++, very high (Taken from [26, 28, 45]).

Tissue	Protein/mRNA	PPARα	PPARβ/δ	PPARγ
GI tract
Mouse	Protein		++++
Human	mRNA	+ or ++	+ to ++++	++ to ++++
Mouse	mRNA	+ or +++
Rat	mRNA	++ to ++++	++ to ++++	+ to ++
Liver
Mouse	Protein		+++
Rat	Protein	++++
Human	mRNA	+ to ++++	+ or ++	+ to ++
Mouse	mRNA	++++
Rat	mRNA	++++	++	−
Kidney
Mouse	Protein		+++
Human	mRNA	++ to ++++	+ to +++	+ to +++
Mouse	mRNA	+++
Rat	mRNA	+++ to ++++	+++	±
Heart
Mouse	Protein		++
Human	mRNA	+++ to ++++	+ or +++	++ to +++
Mouse	mRNA	++
Rat	mRNA	+ or +++	+	±
WAT
Human	mRNA	+	++	++++
Rat	mRNA	+	++	+++
BAT
Mouse	mRNA	+++
Rat	mRNA	++++	++	++++
CNS
Rat	mRNA	+	+ or +++	±
Brain
Mouse	Protein		++
Human	mRNA	++	+ or +++
Rat	mRNA	+	+++
Skeletal muscle
Mouse	Protein		+
Human	mRNA	++ to ++++	++ or ++++	+ or +++
Mouse	mRNA	+++	+++	±
Rat	mRNA	++	++++	±
Skin
Mouse	Protein		+++
Rat	mRNA	+	±
Lung
Mouse	Protein		++
Human	mRNA	+	+ or +++	++++
Rat	mRNA	+	++	+