title: The effects of acute cold exposure on morphology and gene expression in the heart of neonatal chicks.
abstract: Cold exposure induces an increase in blood flow and blood pressure, and long-term exposure to cold causes cardiac hypertrophy. Neonatal chicks (Gallus gallus domesticus) are highly sensitive to cold exposure, because their capacity for thermogenesis is immature until 1 week after hatching. Hence, we hypothesized that the heart of chicks at around 1 week of age acutely responds to cold environment. To investigate the effect of acute (24 h) and long-term (2 weeks) cold on the heart of chicks, 7-day-old chicks were exposed to cold temperature (4 °C) or kept warm (30 °C). Chicks exposed to the cold showed cardiac hypertrophy with marked left ventricular (LV) chamber dilation and wall thickening. On the other hand, long-term cold exposure (2 weeks from 7-day-old) induced an increase in total ventricular mass, but not in LV morphological parameters. Then, we investigated the details of acute cardiac hypertrophy in chicks. Electron microscopy revealed that cardiomyocytes in the hypertrophied LV had enlarged mitochondria with less dense cristae. Although the mRNA expression of lipoprotein lipase in the LV of the cold-exposed chicks significantly increased, the mRNA expression of genes involved in fatty acid β-oxidation did not change in response to cold exposure. In addition, the mRNA expression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha, which enhances mitochondrial biogenesis and function under physiological cardiac hypertrophy, increased in LV of cold-exposed chicks. The study found that acute cold exposure to neonatal chicks induces LV hypertrophy. However, these results suggest that acute cold exposure to chicks might induce both adaptive and maladaptive responses of the LV.
authors.affiliation: Division of Agro-biological Resource Sciences and Technology, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan.|Division of Sports Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Matsubara
authors.affiliation: Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan.
authors.forename: Saki
authors.initials: S
authors.lastname: Shimamoto
authors.affiliation: Division of Agro-biological Resource Sciences and Technology, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan. ijiri@chem.agri.kagoshima-u.ac.jp.|Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan. ijiri@chem.agri.kagoshima-u.ac.jp.
authors.forename: Daichi
authors.initials: D
authors.lastname: Ijiri
authors.affiliation: Department of Biochemical Science and Technology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima, 890-0065, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Ohtsuka
authors.affiliation: Division of Agro-biological Resource Sciences and Technology, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kanai
authors.affiliation: Division of Agro-biological Resource Sciences and Technology, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Hirabayashi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D006332:Cardiomegaly / Q000209:etiology / Q000235:genetics / Q000503:physiopathology*; D002645:Chickens / Q000502:physiology*; D058639:Cold-Shock Response / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles / Q000166:cytology / Q000648:ultrastructure; D032383:Myocytes, Cardiac / Q000648:ultrastructure
keywords: Cardiac hypertrophy; Chick; Cold exposure; PGC-1α