Emmy-Noether Nachwuchsgruppe Saisonale Anpassungen

Dr. Annika Herwig

Division of Animal Physiology
Biocenter Grindel
Martin-Luther-King-Platz 3
20146 Hamburg

Annika.Herwig~AT~uni-hamburg.de
Phone: +49 40 42838 5426
Fax: +49-(0)40-42838 3937

Forschung

Seasonal changes in the environment have a large influence on life in temperate zones. When days are getting shorter, ambient temperature decreases and food availability becomes restricted in winter, animals have to adapt their physiology to those energetic challenges.The physiological adaptations seasonal mammals can show over the year are impressive: Reproduction is temporally restricted, body weight and metabolism can be dramatically altered between seasons.

Because changes in physiology take several weeks or months to be completed, they have to be initiated well in advance. The most important cue for mammals to initiate physiological adaptations are changes in day length (photoperiodic changes). We know that photoperiod signals to the brain via the hormone melatonin which triggers a series of events that eventually lead to changes in control centres for reproduction and energy balance in the hypothalamus. Those changes appear to somehow rewire the set point for energy intake and energy expenditure and thereby define a strict season-specific body weight and metabolism.

The goal of our work is to understand how the brain regulates mammalian long-term changes in energy balance. Our animal model is the Djungarian hamster which shows particularly strong photoperiodic adaptations of body weight, metabolism and reproduction. We aim to clarify the cascade of molecular mechanisms by which hypothalamic centers relay environmental and nutritional signals to the control of metabolism, body temperature and body weight as well as to the pituitary-gonadal axis.

Methods
Microdialysis
Telemetry
Molecular methods
In situ hybridization
Immunocytochemistry

Publikationen

Helwig M, Herwig A, Barrett P, Mercer J, Klingenspor M. Photoperiod-dependent regulation of carboxypeptidase E affects selective processing of neuropeptides in the seasonal Siberian hamster (Phodopus sungorus). J Neuroendocrinol, accepted.

Herwig A, Petri I, Barrett P. Hypothalamic gene expression rapidly changes in response to photoperiod in juvenile Siberian hamsters (Phodopus sungorus). J Neuroendocrinol 2012; 24:991-998.

Nilaweera K*, Herwig A*, Bolborea M, Campbell G, Mayer CD, Morgan PJ, Ebling FJP, Barrett P. Photoperiodic regulation of glycogen metabolism, glycolysis and glutamine synthesis in tanycytes of the Siberian hamster suggests novel roles of tanycytes in hypothalamic function. Glia 2011; 59:1695-1705.
* These authors contributed equally to this work.

Davidson S, Lear M, Shanley L, Hing B, Baizan-Edge, Herwig A, Starkey A, Barrett P, MacKenzie A. Differential activity by polymorphic variants of a remote enhancer that supports galanin expression in the hypothalamus and amygdala; implications for obesity, depression and alcoholism. Neuropsychopharmacology 2011; 36:2211-2221.

Bouma HR, Kroese FGM, Kok JW, Talaei F, Boerema AS, Herwig A, Draghiciu O, van Buiten A, Epema AH, van Dam A, Strijkstra AM, Henning RH. Low body temperature governs the decline of circulating lymphocytes during hibernation through sphingosine-1-phosphate. PNAS 2011; 108:2052-2057.

Herwig A, Wilson D, Logie TJ, Morgan PJ, Mercer JG and Barrett P. Photoperiod and acute energy deficits interact on components of the thyroid hormone system in hypothalamic tanycytes of the Siberian hamster. Am J Physiol Regul Integr Comp Physiol 2009; 296:R1307-R1315.

Cottrell EC, Cripps RL, Duncan JS, Barrett P, Mercer JG, Herwig A, Ozanne SE. Developmental changes in hypothalamic leptin receptor: relationship with the postnatal leptin surge and energy balance neuropeptides in the postnatal rat. Am J Physiol Regul Integr Comp Physiol 2009; 296:R631-639.

Herwig A, Ross AW, Morgan PJ and Barrett P. Hypothalamic thyroid hormone energy balance regulation. Review. Obesity Facts 2008; 1:71-79.

Herwig A, Revel FG, Saboureau M, Steinlechner S and Pévet P. Daily torpor, hibernation and the circadian clock. Hypometabolism in Mammals. Hibernation, Torpor and Cryobiology, 2008; 1:125-133.

Herwig A, Saboureau M, Pévet P and Steinlechner S. Daily torpor affects the molecular machinery of the circadian clock in Djungarian hamsters (Phodopus sungorus). Eur J Neurosci 2007; 26:2739-2746.

Herwig A, Ivanova EA, Lydon H, Barrett P, Steinlechner S and Loudon AS. Histamine H3 receptor and orexin A expression during daily torpor in the Djungarian hamster (Phodopus sungorus). Neuroendocrinol 2007; 19:1001-1007.

Revel FG*, Herwig A*, Garidou ML, Dardente H, Menet JS, Masson-Pévet M, Simonneaux V, Saboureau M and Pévet P. The circadian clock of European hamsters (Cricetus critcetus) stops ticking during hibernation. Proc Natl Acad Sci U S A. 2007; 104(34):13816-20.
* These authors contributed equally to this work.

Herwig A, Revel F, Saboureau M, Pévet P, Steinlechner S. Daily torpor alters multiple gene expression in the suprachiasmatic nucleus and pineal gland of the Djungarian hamster (Phodopus sungorus). Chronobiol Int 2006; 23(1-2):269-76.

Herwig A, Pévet P, Bothorel B, Steinlechner S, Saboureau M. Trans-pineal microdialysis in the Djungarian hamster (Phodopus sungorus): a tool to study seasonal changes of circadian clock activities. J Pineal Res. 2006; 40(2):177-83.