Receptors for NPY and PACAP differ in expression and activity during adipogenesis in the murine 3T3-L1 fibroblast cell line.
OBJECTIVE
Neuropeptides are involved in the regulation of food intake in the central nervous system, but they might also act on peripheral fat tissue via neuropeptide receptors.


METHODS
We investigated the receptor expression and activity of pituitary adenylate cyclase-activating polypeptide (PACAP) and of neuropeptide Y at the mRNA and protein levels in the 3T3-L1 fibroblast line during differentiation into adipocytes. Intracellular calcium concentration was measured by calcium imaging.


RESULTS
The PACAP receptors PAC(1) and VPAC(2) as well as the neuropeptide Y(1) receptor were expressed at the mRNA level in fibroblasts, pre-adipocytes and adipocytes. The mRNA profile of the PAC(1) receptor isoforms showed the HOP sequence, whereas the HIP-isoform was present in subconfluent 3T3-L1 fibroblasts only. At the protein level, the mature 3T3-L1 adipocytes produced the PAC(1) and Y(1) receptors; only the PAC(1) receptor showed carbohydrate residues. Both neuropeptides induced an increase of intracellular calcium in mature adipocytes, which was absent in the precursor cells. These changes in calcium were mediated by Y(1) and PAC(1) receptors as demonstrated by the effects of specific receptor agonists and antagonists.


CONCLUSIONS
As the PAC(1)-HOP receptor variant seems to be responsible for PACAP-mediated calcium influx in many cell types, the HOP sequence might also mediate the increase in intracellular calcium in adipocytes. Because a high intracellular calcium level is associated with lipogenesis, peptidergic innervation of adipose tissue might be involved in stress-induced obesity.
Institute of Anatomy, University of Leipzig, Leipzig, Germany.
Martin T
MT
Gericke
Joanna
J
Kosacka
Daniela
D
Koch
Marcin
M
Nowicki
Thomas
T
Schröder
Albert M
AM
Ricken
Karen
K
Nieber
Katharina
K
Spanel-Borowski
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D050156:Adipogenesis / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D051379:Mice; D020033:Protein Isoforms / Q000819:agonists / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000502:physiology*; D017476:Receptors, Neuropeptide Y / Q000819:agonists / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000502:physiology*; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide / Q000819:agonists / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000502:physiology*
D020033:Protein Isoforms; D017476:Receptors, Neuropeptide Y; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D002118:Calcium