Functional changes of the SCN in spontaneous hypertension but not after the induction of hypertension |
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Authors: | Ajda Yilmaz Andries Kalsbeek Ruud M Buijs |
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Affiliation: | 1. Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience (NIN), an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlandsruudbuijs@gmail.com;3. Hypothalamic Integration Mechanisms, Netherlands Institute for Neuroscience (NIN), an Institute of the Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands;4. Department of Endocrinology and Metabolism, Academic Medical Center (AMC), Amsterdam The Netherlands;5. Department of Cell Biology and Physiology, Institute for Biomedical Research, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico |
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Abstract: | ABSTRACTThe present study investigates the circadian behavior of spontaneously hypertensive rats (SHRs) during the pre-hypertensive and hypertensive stage, with the aim to gain insight into whether observed changes in the functionality of suprachiasmatic nucleus (SCN) in the hypertensive state are cause or consequence of hypertension. Four types of animals were used in this study: (1) SHRs which develop hypertension genetically; (2) their normotensive controls, Wistar Kyoto rats (WKYs); (3) Wistar rats whereby hypertension was surgically induced (2 Kidney 1 Clamp (2K1C) method); and (4) sham-operated control Wistar rats. Period length and activity levels and amplitude changes of locomotor and wheel running activity were determined, in constant conditions, as a measure of the functionality of the SCN. Hereto two conditions were used, constant darkness (0 lux) and constant dim (5 lux) light. SHRs showed a shortened period of their locomotor and running wheel activity rhythms in constant darkness during both pre-hypertensive and hypertensive stages and exhibited period lengthening in constant dim light conditions, only during hypertensive stages. Total amount as well as the amplitude of daily running wheel rhythms showed an inverse correlation with the period length, and this relation was significantly different in SHRs compared to WKYs. None of the aforementioned changes in circadian rhythms were observed after the surgical induction of hypertension. The present findings suggest early functional changes of the SCN in the etiology of spontaneous hypertension. |
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Keywords: | Suprachiasmatic nucleus SHR blood pressure activity |
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