Key result
Partial SCN lesions in rats cause arrhythmic activity in darkness but preserve light-driven diurnal patterns.
Why the study?
The study was conducted to explore the role of the suprachiasmatic nucleus for masking by light in rats bearing bilateral complete or partial lesions of the suprachiasmatic nucleus.
The suprachiasmatic nucleus is necessary for masking by light, and behavioral indicators of SCN lesions require testing in at least two lighting conditions.
Necessitates dual lighting conditions to confirm SCN lesions in rodents; leaves open translation to human circadian-cardiovascular research.
Background and objective: To explore the role of the suprachiasmatic nucleus (SCN) for masking by light in rats bearing bilateral complete or partial lesions of the suprachiasmatic nucleus. Methods: Rats were submitted to electrolytic SCN lesions, and their spontaneous activity was monitored to verify arrhythmia in different lighting conditions, under light/dark cycle and constant darkness. Results: Rats bearing a partial suprachiasmatic nucleus lesion presented arrhythmic activity patterns when assessed in constant darkness; however, in a light-dark cycle, rats show a diurnal pattern. Partial lesions were evidenced through histological analysis. Conclusions: We conclude that when behavioral indicators are used evidence suprachiasmatic nucleus lesions, animals should be tested at least in two lighting conditions; we also conclude that the suprachiasmatic nucleus is necessary for masking by light.
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Ángeles-Castellanos et al. (2010) studied Suprachiasmatic nucleus lesions. Electrolytic SCN lesions and different lighting conditions was evaluated on Spontaneous activity patterns. Rats with partial suprachiasmatic nucleus lesions presented arrhythmic activity in constant darkness but a diurnal pattern in a light-dark cycle, showing the SCN is necessary for masking by light.
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