title: Systemic nicotine stimulates human adipose tissue lipolysis through local cholinergic and catecholaminergic receptors.
abstract: OBJECTIVE
  To evaluate whether the lipolytic effects of systemic nicotine are not only attributed to indirect adrenergic mechanisms, but also to a direct action of nicotine on fat cells.
  
  
  METHODS
  The effect of a systemic nicotine infusion (0.5 microg/kg/min for 30 min) on lipolysis in subcutaneous adipose tissue was investigated in situ in 11 non-obese, non-smoking, healthy male subjects under placebo-controlled conditions.
  
  
  METHODS
  By using microdialysis probes the glycerol levels (lipolysis index) and blood flow were monitored locally in subcutaneous adipose tissue.
  
  
  RESULTS
  Plasma nicotine levels peaked (7.2 ng/ml) at the end of the infusion. Nicotine induced a mean (+/-s.e.) percentage peak increase in adrenaline and noradrenaline plasma levels of 213+/-30% (P<0.01) and 118+/-5% (P<0.05), respectively. Nicotine increased venous plasma glycerol levels by 144+/-9% (P<0.001), arterialized plasma glycerol levels by 148+/-12% (P<0.001) and adipose glycerol levels by 148+/-16% (P<0.001), but did not alter blood flow. By inducing a local cholinoceptor blockade with mecamylamine (10(-5) M) via the microdialysis system, the increase in adipose glycerol levels was inhibited by approximately 45% (P=0.02). A corresponding local beta-adrenoceptor blockade with propranolol (10(-4) M), inhibited the increase in adipose glycerol levels by approximately 60% (P=0.02). Infusion of saline (ie placebo) had no effect on the parameters mentioned above.
  
  
  CONCLUSIONS
  Systemically administered nicotine induces lipolysis, in part by activating the classical adrenergic mechanism (mediated by a nicotine-induced release of catecholamines stimulating beta-adrenoceptors), and in part by directly activating a nicotinic cholinergic lipolytic receptor located in adipose tissue.
authors.affiliation: Department of Medicine and Research Center, Huddinge Hospital, Karolinska Institute, Huddinge, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Andersson
authors.forename: P
authors.initials: P
authors.lastname: Arner
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D005990:Glycerol / Q000097:blood; D006801:Humans; D007262:Infusions, Intravenous; D007700:Kinetics; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D017551:Microdialysis; D009538:Nicotine / Q000008:administration & dosage* / Q000097:blood*; D018722:Nicotinic Agonists / Q000494:pharmacology; D017983:Receptors, Catecholamine / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000378:metabolism*
chemical_list: D018722:Nicotinic Agonists; D017983:Receptors, Catecholamine; D011950:Receptors, Cholinergic; D009538:Nicotine; D005990:Glycerol