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Circadian timekeeping in hyperactive and hypertensive inbred rat strains
A M Rosenwasser1, M W Pellowski, E D Hendley
1Department of Psychology, University of Maine, Orono 04469, USA. ALANR@MAINE.MAINE.EDU
The American Journal of Physiology
|September 1, 1996
Summary
This study investigated circadian rhythms in genetically hyperactive (WKHA) and hypertensive (WKHT) rats. Findings suggest circadian period may link to hypertension, while entrainment and phase shifting link to hyperactivity.
Area of Science:
- Chronobiology
- Behavioral Genetics
- Physiology
Background:
- Inbred rat strains offer models for studying genetic and physiological traits.
- Circadian rhythms influence various physiological processes and can be strain-specific.
Purpose of the Study:
- To characterize circadian timekeeping in genetically hyperactive (WKHA) and hypertensive (WKHT) inbred rat strains.
- To explore genetic and physiological relationships between circadian rhythmicity and strain-specific behaviors like hyperactivity and hypertension.
Main Methods:
- Characterization of free-running period, light-dark cycle entrainment, and photic phase shifting in WKHA and WKHT rats.
- Comparison of circadian traits between WKHA/WKHT strains and their parent strains (SHR and WKY).
Main Results:
- WKHA and WKHT rats exhibited distinct differences in free-running period, entrainment, and phase shifting.
- Short circadian period in WKHT rats may be genetically linked to hypertension.
- Similar photic entrainment and phase shifting in WKHA rats suggest a link to open-field hyperactivity.
- Neither WKHA nor WKHT strains displayed the excessive running wheel activity seen in SHR rats, indicating this trait is independent of hypertension and hyperactivity.
Conclusions:
- Circadian period, entrainment, and phase shifting show differential genetic associations with hypertension and hyperactivity in these rat models.
- The study provides insights into the genetic and physiological underpinnings of circadian rhythmicity and its relationship with complex behavioral traits.