Photic induction of Fos in the SCN of African mole-rats : responses to increasing irradiance.

dc.contributor.authorOosthuizen, Maria Kathleen
dc.contributor.authorBennett, Nigel Charles
dc.contributor.authorCooper, Howard M.
dc.date.accessioned2010-11-15T10:39:49Z
dc.date.available2010-11-15T10:39:49Z
dc.date.issued2010-10
dc.description.abstractAfrican mole-rats (family Bathyergidae) are strictly subterranean rodent species that are rarely exposed to environmental light. Morphological and physiological adaptations to the underground environment include a severely reduced eye size and regressed visual system. Responses of the circadian system to light, however, appear to be intact, since mole-rats are able to entrain their circadian activity rhythms to the light-dark cycle and light induces Fos expression in the suprachiasmatic nucleus (SCN). Social organization varies from solitary species to highly elaborated eusocial structures, characterized by a distinct division of labor and in which one reproductive female regulates the behavior and reproductive physiology of other individuals in the colony. The authors studied light-induced Fos expression in the SCN to increasing light intensities in four mole-rat species, ranging from strictly solitary to highly social. In the solitary Cape mole-rat, light induces significant Fos expression in the SCN, and the number of Fos-immunopositive cells increases with increasing light intensity. In contrast, Fos induction in the SCN of social species was slightly greater than, but not statistically different from, the dark-control animals as is typical of most rodents. One species showed a trend for an increase in expression with increased light, whereas a second species showed no trend in expression. In the naked mole-rat, Fos expression appeared higher in the dark-controls than in the animals exposed to light, although the differences in Fos expression were not significant. These results suggest a gradient in the sensitivity of the circadian system to light in mole-rats, with a higher percentage of individuals that are unresponsive to light in correlation with the degree of sociality. In highly social species, such as the naked mole-rat that live in a relatively stable subterranean milieu in terms of food availability, temperature, constant darkness, and devoid of 24-h cyclic environmental cues, the temporal coordination of rest-wake activities may be dependent on social interactions and social status rather than on photic regulation of the circadian timing system. [Abstract from author]en
dc.identifier.citationOosthuizen, MK, Bennett, NC, & Cooper, HM 2010, 'Photic induction of Fos in the SCN of African mole-rats : responses to increasing irradiance', Chronobiology International, vol. 27, no. 8, pp, 1532-1545. [http://informahealthcare.com/loi/cbi]en
dc.identifier.issn0742-0528
dc.identifier.other10.3109/07420528.2010.510227
dc.identifier.urihttp://hdl.handle.net/2263/15284
dc.language.isoenen
dc.publisherInforma Healthcareen
dc.rightsInforma Healthcare. This is an electronic version of an article published in Oosthuizen, MK, Bennett, NC, & Cooper, HM 2010, 'Photic induction of Fos in the SCN of African mole-rats : responses to increasing irradiance', Chronobiology International, vol. 27, no. 8, pp, 1532-1545. [http://informahealthcare.com/loi/cbi]. Chronobiology International is available online at informaworld.en
dc.subjectFosen
dc.subjectLight intensityen
dc.subjectSuprachiasmatic nucleus (SCN)en
dc.subjectMole-ratsen
dc.subject.lcshBathyergidaeen
dc.subject.lcshBrightness perceptionen
dc.subject.lcshVisual evoked responseen
dc.subject.lcshSpectral irradianceen
dc.titlePhotic induction of Fos in the SCN of African mole-rats : responses to increasing irradiance.en
dc.typePostprint Articleen

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