Fat metabolism in High Arctic Svalbard ptarmigan
1.Purpose
The inability to loose excess fat-stores once they have been deposited is a major human and animal health problem. The Svalbard ptarmigan, Lagopus muta hyperborea (SvPt), is the prototypical example of those few species in which high amplitude cycles of fat accumulation and depletion form part of the healthy cycle of annual change. In SvPt the seasonal cycle of body fattening involves extensive accumulation of fat stores in preparation for the winter, which are then lost rapidly prior to the breeding season. At its body mass peak, SvPt can weigh 50% more than at their summer nadir: in human terms equating to a shift in BMI from a healthy 20 to a morbidly obese 30. This occurs without any apparent detrimental health consequences and is not due to limiting food supply, since the cycle persists in ad libitum fed birds. This ability to undergo cyclical accumulation and depletion of fat-stores makes SvPt the ideal model for obesity research.
We hypothesise that the annual cycle of body fattening in SvPt depends on a photoperiodically-driven shift in the relative contributions of food-intake and lipid mobilization to cellular energy homeostasis. We propose to test this hypothesis by an experiment that combines photoperiodic manipulation with longitudinal monitoring of physiological and behavioural parameters: activity, feed intake, body temperature, body mass, plasma metabolites and respirometry.
2.Distress
Activity recording, weighing and food-monitoring cause minimal distress. Blood sampling will cause mild distress. Surgical implantation of temperature and heart-rate loggers under anaesthesia will cause moderate distress.
3.Expected benefit
New information about how SvPt shift between intake-based and mobilization-based strategies during the annual fattening cycle, leading to medically important insights into means for reducing obesity.
4.Animals
42 Svalbard ptarmigan
5. 3Rs
Replacement: Krogh's principle states: "for such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied." (AmJPhys, 1929). SvPt express unique characteristics in terms of their seasonal fattening cycle that can shed new light in obesity research. There are no standard laboratory animals that express similar evolutionary-derived characteristics. This means that the present study can only be studied using this uniquely suited model. After completion of experiments, remaining birds will become founders for breeding in the 8million NOK new ptarmigan-facility that is under construction at UiT, in response to Mattilsynet’s demand for such a facility after the previous inspection (VSID1728).
Reduction: Several automated behavioural and physiological measurements are performed. This will result in a wealth of data and reduce need of animals in future experiments. Due to the changes in photoperiod and the continuous monitoring, all birds can partially act as their own control. This increases statistical power and reduces sample size.
Refinement: We constantly re-evaluate our experimental procedure to decrease distress for our experimental birds, e.g. by using smaller temperature logger implants. We also use hand-reared birds in our project. The habituation to handling from a young age (which includes wild-captured as well as captivity-bred chicks) minimises handling-related stress.
The inability to loose excess fat-stores once they have been deposited is a major human and animal health problem. The Svalbard ptarmigan, Lagopus muta hyperborea (SvPt), is the prototypical example of those few species in which high amplitude cycles of fat accumulation and depletion form part of the healthy cycle of annual change. In SvPt the seasonal cycle of body fattening involves extensive accumulation of fat stores in preparation for the winter, which are then lost rapidly prior to the breeding season. At its body mass peak, SvPt can weigh 50% more than at their summer nadir: in human terms equating to a shift in BMI from a healthy 20 to a morbidly obese 30. This occurs without any apparent detrimental health consequences and is not due to limiting food supply, since the cycle persists in ad libitum fed birds. This ability to undergo cyclical accumulation and depletion of fat-stores makes SvPt the ideal model for obesity research.
We hypothesise that the annual cycle of body fattening in SvPt depends on a photoperiodically-driven shift in the relative contributions of food-intake and lipid mobilization to cellular energy homeostasis. We propose to test this hypothesis by an experiment that combines photoperiodic manipulation with longitudinal monitoring of physiological and behavioural parameters: activity, feed intake, body temperature, body mass, plasma metabolites and respirometry.
2.Distress
Activity recording, weighing and food-monitoring cause minimal distress. Blood sampling will cause mild distress. Surgical implantation of temperature and heart-rate loggers under anaesthesia will cause moderate distress.
3.Expected benefit
New information about how SvPt shift between intake-based and mobilization-based strategies during the annual fattening cycle, leading to medically important insights into means for reducing obesity.
4.Animals
42 Svalbard ptarmigan
5. 3Rs
Replacement: Krogh's principle states: "for such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied." (AmJPhys, 1929). SvPt express unique characteristics in terms of their seasonal fattening cycle that can shed new light in obesity research. There are no standard laboratory animals that express similar evolutionary-derived characteristics. This means that the present study can only be studied using this uniquely suited model. After completion of experiments, remaining birds will become founders for breeding in the 8million NOK new ptarmigan-facility that is under construction at UiT, in response to Mattilsynet’s demand for such a facility after the previous inspection (VSID1728).
Reduction: Several automated behavioural and physiological measurements are performed. This will result in a wealth of data and reduce need of animals in future experiments. Due to the changes in photoperiod and the continuous monitoring, all birds can partially act as their own control. This increases statistical power and reduces sample size.
Refinement: We constantly re-evaluate our experimental procedure to decrease distress for our experimental birds, e.g. by using smaller temperature logger implants. We also use hand-reared birds in our project. The habituation to handling from a young age (which includes wild-captured as well as captivity-bred chicks) minimises handling-related stress.