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Appropriate and inappropriate hypothalamic cold thermosensitivity in Willow ptarmigan
1Department of Arctic Biology, University of Tromsø, Norway.
Acta Physiologica Scandinavica
|September 1, 1987
Summary
Willow Ptarmigan exhibit mammalian-like hypothalamic thermosensitivity, suggesting fundamental similarities in temperature regulation between birds and mammals. This research identifies specific cold thermosensors in the bird
Area of Science:
- Physiology
- Neuroscience
- Comparative Biology
Background:
- Hypothalamic thermosensitivity is crucial for maintaining core body temperature (Tc).
- Understanding avian thermoregulation provides insights into evolutionary biology.
- Willow Ptarmigan (Lagopus lagopus lagopus) serve as a model for avian thermoregulation studies.
Purpose of the Study:
- To investigate hypothalamic thermosensitivity in conscious Willow Ptarmigan.
- To compare avian thermoregulatory responses to mammalian patterns.
- To identify the presence and nature of cold thermosensors in the avian hypothalamus.
Main Methods:
- Conscious Willow Ptarmigan were equipped with chronically implanted hypothalamic perfusion thermodes.
- Birds were subjected to cold (Ta -10°C) and warm (Ta +25°C) ambient temperatures.
- Hypothalamic temperature (Thy) was clamped at various set levels (28°C–43°C) for 20 minutes.
Main Results:
- Hypothalamic heating inhibited shivering in cold, lowering Tc (mammalian-like response).
- Hypothalamic cooling at 34-36°C facilitated shivering, increasing Tc (mammalian-like response).
- Hypothalamic heating and weak cooling modulated panting in warm conditions (mammalian-like responses).
Conclusions:
- Willow Ptarmigan display weak, mammalian-like cold hypothalamic thermosensitivity.
- The study suggests the presence of specific cold thermosensors in the avian hypothalamus.
- Hypothalamic temperature dependence in birds and mammals appears fundamentally similar.