Seasonal changes in membrane lipid transitions and thyroid function in the hedgehog

Area of Science:

• Physiology
• Biochemistry
• Animal Biology

Background:

• Cell membrane fluidity is crucial for animal adaptation to environmental changes.
• Hedgehogs (Erinaceus europaeus) exhibit significant seasonal physiological changes, including hibernation.

Purpose of the Study:

• To investigate seasonal variations in the order-disorder transition temperatures of hedgehog blood cell lipids.
• To determine the relationship between these lipid changes, metabolic rate, and thyroid hormone levels.
• To ascertain if winter lipid adaptations are a direct response to cold or a broader homeostatic mechanism.

Main Methods:

• Determination of upper (Tf) and lower (Ts) temperature limits of lipid order-disorder transitions in hedgehog blood cells throughout the year.
• Measurement of plasma thyroxine levels in summer and winter hedgehogs.
• Assessment of basal oxygen consumption in hedgehogs under different winter conditions.

Main Results:

• Significant decreases in Tf and Ts were observed from summer (19°C, 6°C) to winter (14°C, -2.0°C).
• Plasma thyroxine levels and basal oxygen consumption were lower in winter compared to summer.
• No significant differences in these parameters were found between indoor and outdoor winter-housed hedgehogs.

Conclusions:

• Winter-associated changes in hedgehog membrane lipids and metabolism are part of a circannual homeostatic adjustment.
• Thyroid hormone levels play a significant role in regulating these seasonal adaptations.
• The observed changes are not solely a response to low ambient temperatures but a coordinated physiological response.