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Development of vasomotor control in lean (+/?) and genetically obese (fa/fa) rat pups
1Max-Planck-Institut für physiologische und klinische Forschung, W.G. Kerckhoff-Institut, Bad Nauheim, Germany.
Insights
Rat pups as young as 7 days old demonstrate functional vasomotor control, with responses to temperature changes. Fatty rat pups showed altered metabolic responses but similar vasomotor control compared to lean pups.
Area of Science:
- Physiology
- Developmental Biology
- Animal Models
Background:
- Vasomotor control is crucial for thermoregulation.
- Understanding the developmental timeline of vasomotor control in mammals is important.
- Obesity can impact physiological regulatory systems.
Purpose of the Study:
- To determine if vasomotor control is functional in young rat pups (7, 11, and 16 days old).
- To investigate potential differences in vasomotor responses between lean and fatty (fa/fa) 16-day-old rat pups.
Main Methods:
- Laser Doppler flowmetry was used to measure skin blood flux.
- Rat pups were exposed to controlled changes in ambient temperature (Ta).
- Core temperature (Tc) and metabolic rate (MR) were monitored alongside blood flux.
Main Results:
- Significant changes in hindpaw blood flux were observed in all age groups in response to Ta shifts.
- Younger pups (7-day-old) exhibited faster blood flux responses than older pups (16-day-old).
- Fatty (fa/fa) pups showed altered metabolic rate responses to cold but comparable vasomotor control to lean pups.
Conclusions:
- The vasomotor control system is functional in rat pups by 7 days of age.
- Vasomotor responses mature with age, showing faster adjustments in younger pups.
- The fa/fa genetic mutation primarily affects metabolic cold defense rather than vasomotor control.
Abstract:
Using laser Doppler flowmetry, we determined whether vasomotor control is already functional in 7-, 11-, and 16-day-old rat pups, and whether differences in vasomotor responses between 16-day-old lean (+/?) and fatty (fa/fa) pups occur. For 3 h, at the end of their daily light phase, the pups were exposed to 30-min step changes of ambient temperature (Ta) alternating between thermoneutrality and cold loads resulting in a 50-100% increase of metabolic rate (MR) above its thermoneutral value, while core temperature (Tc), skin blood flux at the hindpaw, and MR were recorded. In all age groups, blood flux changed significantly in response to these Ta changes. The time needed for a significant change in blood flux was shorter in the 7-day-old than in the 16-day-old lean pups, while the Ta dependency of Tc was more pronounced in the younger pups. Comparison of the responses of the 16-day-old fatty and lean pups showed a parallel shift to lower values in the correlation of Ta with MR in the fa/fa pups, but no difference in the correlation of Ta with blood flux. This demonstrates that the vasomotor control system in the rat is already functional by the age of 7 days, and that the fa/fa lesion influences the vasomotor control less than the metabolic cold defense.