title: Pinealectomy alters adipose tissue adaptability to fasting in rats.
abstract: This study investigated the effects of pinealectomy and fasting on rat adipose tissue metabolism, as well as on profiles of the hormones directly involved in its regulation (insulin, leptin, and corticosterone). Pinealectomized (PINX) and sham-operated (CONTROL) adult male Wistar rats were killed 6 weeks after surgery, in either fed or fasted (12 and 36 hours) states. Blood samples (for glucose and hormone determinations) and peri-epididymal adipocytes (for in vitro insulin-stimulated glucose uptake, oxidation, and incorporation into lipids) were collected. Pineal ablation decreased insulin-stimulated glucose uptake in adipocytes of both fed and fasted animals without affecting insulin-binding capacity. Pinealectomy attenuated the reduction in the ability to oxidize glucose in both basal and insulin-stimulated states during fasting. This alteration in the ability of adipocytes to oxidize glucose appeared together with a decrease in insulin-induced glucose incorporation into lipids in PINX animals. Additionally, pinealectomized rats showed higher corticosterone levels in both fed and fasted states, and a lower leptinemia with 36 hours of fasting, in comparison to CONTROLs. In conclusion, our data reinforce the hypothesis that the pineal gland has a role in the modulation of adipocyte metabolism, and its absence alters metabolic adaptation to fasting in rats.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Maria Isabel Cardoso
authors.initials: MI
authors.lastname: Alonso-Vale
authors.forename: Gabriel Forato
authors.initials: GF
authors.lastname: Anhê
authors.forename: Cristina das Neves
authors.initials: Cd
authors.lastname: Borges-Silva
authors.forename: Sandra
authors.initials: S
authors.lastname: Andreotti
authors.forename: Sidney Barnabé
authors.initials: SB
authors.lastname: Peres
authors.forename: José
authors.initials: J
authors.lastname: Cipolla-Neto
authors.forename: Fabio Bessa
authors.initials: FB
authors.lastname: Lima
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000273:Adipose Tissue / Q000502:physiology*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D048429:Cell Size; D003345:Corticosterone / Q000097:blood; D003847:Deoxyglucose / Q000378:metabolism; D004435:Eating / Q000502:physiology; D005215:Fasting / Q000097:blood / Q000502:physiology*; D007328:Insulin / Q000097:blood / Q000494:pharmacology; D020738:Leptin / Q000097:blood; D050356:Lipid Metabolism; D008297:Male; D010870:Pineal Gland / Q000502:physiology / Q000601:surgery*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D001786:Blood Glucose; D007328:Insulin; D020738:Leptin; D002245:Carbon Dioxide; D003847:Deoxyglucose; D003345:Corticosterone