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Short photoperiod exposure increases adipocyte sensitivity to noradrenergic stimulation in Siberian hamsters.

Abstract

Siberian hamsters (Phodopus sungorus) exhibit a naturally occurring, reversible seasonal obesity with body fat peaking in long "summerlike" days (LDs) and reaching a nadir in short "winterlike" days (SDs). These SD-induced decreases in adiposity are mediated largely via sympathetic nervous system (SNS) innervation of white adipose tissue (WAT), as indicated by increased WAT norepinephrine (NE) turnover. We examined whether SDs also increase sensitivity to NE-stimulated lipolysis. This was accomplished by measuring NE- and beta3-adrenoceptor (beta3-AR) agonist (BRL-37344)-induced lipolysis (glycerol release) as well as NE-induced cAMP accumulation by inguinal, epididymal, and retroperitoneal WAT (IWAT, EWAT, and RWAT) in isolated adipocytes of LD- and SD-housed hamsters. SDs increased potency/efficacy of NE-triggered lipolysis in a temporally and fat pad-specific manner. Thus when WAT pad mass decreased most rapidly (5 wk of SDs), potency (sensitivity/EC50) and efficacy (maximal response asymptote) of NE-stimulated lipolysis were increased for all WAT pads and also at 10 wk for IWAT compared with their LD counterparts. SD enhancement of lipolysis was similar for NE and BRL-37344 in IWAT adipocytes. These results, coupled with our previous demonstration that SDs upregulate WAT beta3-AR mRNA expression, suggest that increased beta3-ARs mediated the SD-induced increased NE sensitivity. NE-stimulated adipocyte accumulation of cAMP was greater after 5 wk of SDs for IWAT and EWAT and after 10 wk of SDs for IWAT compared with LDs, with no photoperiod effect for RWAT. Therefore, the SD-induced increase in SNS drive to WAT and increased sensitivity to this drive may work together to increase lipolysis in SDs.

Authors+Show Affiliations

Molecular and Cellular Biology and Pathobiology Program, Medical University of South Carolina, Charleston, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15821285

Citation

Bowers, Robert R., et al. "Short Photoperiod Exposure Increases Adipocyte Sensitivity to Noradrenergic Stimulation in Siberian Hamsters." American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, vol. 288, no. 5, 2005, pp. R1354-60.
Bowers RR, Gettys TW, Prpic V, et al. Short photoperiod exposure increases adipocyte sensitivity to noradrenergic stimulation in Siberian hamsters. Am J Physiol Regul Integr Comp Physiol. 2005;288(5):R1354-60.
Bowers, R. R., Gettys, T. W., Prpic, V., Harris, R. B., & Bartness, T. J. (2005). Short photoperiod exposure increases adipocyte sensitivity to noradrenergic stimulation in Siberian hamsters. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 288(5), pp. R1354-60.
Bowers RR, et al. Short Photoperiod Exposure Increases Adipocyte Sensitivity to Noradrenergic Stimulation in Siberian Hamsters. Am J Physiol Regul Integr Comp Physiol. 2005;288(5):R1354-60. PubMed PMID: 15821285.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Short photoperiod exposure increases adipocyte sensitivity to noradrenergic stimulation in Siberian hamsters. AU - Bowers,Robert R, AU - Gettys,Thomas W, AU - Prpic,Veronica, AU - Harris,Ruth B S, AU - Bartness,Timothy J, PY - 2005/4/12/pubmed PY - 2005/5/25/medline PY - 2005/4/12/entrez SP - R1354 EP - 60 JF - American journal of physiology. Regulatory, integrative and comparative physiology JO - Am. J. Physiol. Regul. Integr. Comp. Physiol. VL - 288 IS - 5 N2 - Siberian hamsters (Phodopus sungorus) exhibit a naturally occurring, reversible seasonal obesity with body fat peaking in long "summerlike" days (LDs) and reaching a nadir in short "winterlike" days (SDs). These SD-induced decreases in adiposity are mediated largely via sympathetic nervous system (SNS) innervation of white adipose tissue (WAT), as indicated by increased WAT norepinephrine (NE) turnover. We examined whether SDs also increase sensitivity to NE-stimulated lipolysis. This was accomplished by measuring NE- and beta3-adrenoceptor (beta3-AR) agonist (BRL-37344)-induced lipolysis (glycerol release) as well as NE-induced cAMP accumulation by inguinal, epididymal, and retroperitoneal WAT (IWAT, EWAT, and RWAT) in isolated adipocytes of LD- and SD-housed hamsters. SDs increased potency/efficacy of NE-triggered lipolysis in a temporally and fat pad-specific manner. Thus when WAT pad mass decreased most rapidly (5 wk of SDs), potency (sensitivity/EC50) and efficacy (maximal response asymptote) of NE-stimulated lipolysis were increased for all WAT pads and also at 10 wk for IWAT compared with their LD counterparts. SD enhancement of lipolysis was similar for NE and BRL-37344 in IWAT adipocytes. These results, coupled with our previous demonstration that SDs upregulate WAT beta3-AR mRNA expression, suggest that increased beta3-ARs mediated the SD-induced increased NE sensitivity. NE-stimulated adipocyte accumulation of cAMP was greater after 5 wk of SDs for IWAT and EWAT and after 10 wk of SDs for IWAT compared with LDs, with no photoperiod effect for RWAT. Therefore, the SD-induced increase in SNS drive to WAT and increased sensitivity to this drive may work together to increase lipolysis in SDs. SN - 0363-6119 UR - https://www.unboundmedicine.com/medline/citation/15821285/Short_photoperiod_exposure_increases_adipocyte_sensitivity_to_noradrenergic_stimulation_in_Siberian_hamsters_ L2 - http://www.physiology.org/doi/full/10.1152/ajpregu.00792.2004?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -