title: Postnatal light alters hypothalamic-pituitary-adrenal axis function and induces a depressive-like phenotype in adult mice.
abstract: The postnatal light environment that a mouse experiences during the critical first three postnatal weeks has long-term effects on both its circadian rhythm output and clock gene expression. Furthermore, data from our lab suggest that postnatal light may also impact the hypothalamic-pituitary-adrenal (HPA) axis, which is a key regulator of stress. To test the effect of postnatal light exposure on adult stress responses and circadian rhythmicity, we raised mice under either 24-h light-dark cycles (LD), constant light (LL) or constant dark (DD) during the first three postnatal weeks. After weaning we then exposed all animals to LD cycles (basal conditions), followed by LL (stressed conditions) environments. We examined brain neuropeptide and glucocorticoid receptor (GR) expression, plasma corticosterone concentration rhythm and body temperature rhythm, together with depression- and anxiety-related behaviour. Results showed that LL- and DD-raised mice exhibited decreased GR expression in the hippocampus, increased plasma corticosterone concentration at the onset of the dark phase and a depressive phenotype when exposed to LD cycles later in life. Furthermore, LL-raised mice showed increased corticotrophin-releasing hormone mRNA expression in the paraventricular nucleus of the hypothalamus. When exposed to LL as adults, LL-raised mice showed a significant circadian rhythm of plasma corticosterone concentration, together with a shorter period and stronger circadian rhythm of body temperature compared to DD-raised mice. Taken together, these data suggest that altered postnatal light environments have long-term effects on the HPA axis and the circadian system, which can lead to altered stress responses and a depressive phenotype in adulthood.
authors: Faculty of Life Sciences, University of Manchester, AV Hill Building, Oxford Road, M13 9PT, Manchester, UK.
authors: Georgia
authors: G
authors: Coleman
authors: Faculty of Life Sciences, University of Manchester, AV Hill Building, Oxford Road, M13 9PT, Manchester, UK.
authors: John
authors: J
authors: Gigg
authors: Faculty of Life Sciences, University of Manchester, AV Hill Building, Oxford Road, M13 9PT, Manchester, UK.
authors: Maria Mercè
authors: 0000-0002-1077-6844
authors: MM
authors: Canal
mesh_terms: D000818:Animals; D001831:Body Temperature; D002940:Circadian Rhythm; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000235:genetics / Q000378:metabolism; D003863:Depression / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D007030:Hypothalamo-Hypophyseal System / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D008027:Light / Q000009:adverse effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D017440:Photoperiod; D010913:Pituitary-Adrenal System / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000378:metabolism; D013315:Stress, Psychological / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D011965:Receptors, Glucocorticoid; D018013:Receptors, Neuropeptide; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone
keywords: body temperature; circadian rhythm; constant darkness; constant light; corticosterone; corticotrophin-releasing hormone