Distribution of PYY receptors in human fat cells: an antilipolytic system alongside the alpha 2-adrenergic system.
The antilipolytic effect of peptide YY (PYY) and neuropeptide Y has recently been shown in human adipocytes. PYY receptors were investigated in three human adipose deposits. A greater number of 125I-labeled PYY binding sites was found in femoral adipocyte membranes (maximal binding = 40 +/- 4 fmol/mg protein; dissociation constant = 0.3 +/- 0.1 nM) when compared with mammary and pericolonic adipose tissue. PYY receptors, like alpha 2-adrenergic sites, were largely expressed in femoral fat cells. Such a distribution was not specific either to inhibitory or to stimulating adenylyl cyclase systems since adenosine A1 and beta-adrenergic receptors were more numerous in pericolonic adipocytes. On isolated adipocytes, PYY (10(-7) M) inhibited lipolysis by 58 +/- 2% in femoral and 14 +/- 4% in pericolonic fat cells; epinephrine had the following similar response: 62 +/- 5 and 26 +/- 8%, respectively. A close relationship between the number of alpha 2-sites and PYY sites and the antilipolytic effects initiated by PYY and an alpha 2-agonist was observed. No significant differences were noted in the amount of Gi proteins in femoral and pericolonic adipocyte membranes.
Castan
I
I
Institut National de la Santé et de la Recherche Médicale, Unité 317, Institut Louis Bugnard, Université Paul Sabatier, Toulouse, France.
Valet
P
P
Larrouy
D
D
Voisin
T
T
Remaury
A
A
Daviaud
D
D
Laburthe
M
M
Lafontan
M
M
D000273:Adipose Tissue / Q000166:cytology / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003106:Colon; D005269:Femur; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D008066:Lipolysis; D011869:Radioligand Assay; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000378:metabolism; D011964:Receptors, Gastrointestinal Hormone; D014018:Tissue Distribution
D011942:Receptors, Adrenergic, alpha; D011956:Receptors, Cell Surface; D011964:Receptors, Gastrointestinal Hormone; C082172:peptide YY receptor; D019204:GTP-Binding Proteins