title: Neonatal nicotine exposure alters leptin signaling in the hypothalamus-pituitary-thyroid axis in the late postnatal period and adulthood in rats.
abstract: OBJECTIVE
  Postnatal nicotine exposure causes precocious primary hypothyroidism and programs for overweight, hyperleptinemia and secondary hypothyroidism in adulthood. As leptin and thyroid hormones share the ability to increase energy expenditure, we studied the effects of maternal nicotine exposure during lactation on the leptin signaling in the hypothalamus-pituitary-thyroid axis of suckling and adult offspring.
  
  
  METHODS
  Two days after delivery, osmotic minipumps were implanted in lactating rats, and nicotine (NIC, 6 mg/kg/day s.c.) or saline (C) was administered for 14days. Offspring were killed at 15 and 180 days-old. Proteins belonging to leptin signaling were analyzed by Western blot. Significant differences had p<0.05.
  
  
  RESULTS
  In the hypothalamus, NIC offspring showed higher OB-R and pSTAT-3 content (+58%,+1.34x) at 15 days, and lower OB-R, JAK-2 and pSTAT-3 (-61%, -42%, -56%) at 180 days. In the pituitary gland, NIC offspring showed lower JAK-2 content (-52%) at 15 days, but no differences in adulthood. In the thyroid gland, the NIC group presented lower OB-R, JAK-2 and STAT-3 (-44%, -50%, -47%) and higher pSTAT-3 expression (+80%) at 15 days. At 180 days-old, NIC offspring presented higher thyroid OB-R (+1.54x) and lower pSTAT-3 content (-34%).
  
  
  CONCLUSIONS
  Neonatal primary hypothyroidism induced by maternal nicotine exposure during lactation may be partially explained by decreased leptin signaling in the thyroid, though the early stimulation of the central leptin pathway did not prevent the thyroid dysfunction. Long-term effects of postnatal nicotine exposure on leptin signaling in the hypothalamus and thyroid appear to involve central and peripheral leptin resistance in adulthood.
authors.affiliation: Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: A P
authors.initials: AP
authors.lastname: Santos-Silva
authors.forename: E G
authors.initials: EG
authors.lastname: Moura
authors.forename: C R
authors.initials: CR
authors.lastname: Pinheiro
authors.forename: A S
authors.initials: AS
authors.lastname: Rios
authors.forename: Y
authors.initials: Y
authors.lastname: Abreu-Villaça
authors.forename: M C F
authors.initials: MC
authors.lastname: Passos
authors.forename: E
authors.initials: E
authors.lastname: Oliveira
authors.forename: P C
authors.initials: PC
authors.lastname: Lisboa
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000833:Animals, Suckling; D015153:Blotting, Western; D005260:Female; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D007037:Hypothyroidism / Q000139:chemically induced; D007774:Lactation; D020738:Leptin / Q000378:metabolism*; D008297:Male; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects*; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D020738:Leptin; D018722:Nicotinic Agonists; D009538:Nicotine