Chronic cold stress regulates ascending noradrenergic pathways

• Published in: Neuroscience 2004, Vol.127 (4), p.949-960
• Main Authors: Featherby, T., Lawrence, A.J.
• Format: Article
• Language: English
• Subjects: Afferent Pathways - enzymology; Afferent Pathways - metabolism; Animals; Biological and medical sciences; caudal ventrolateral medulla; Cold Temperature - adverse effects; Fundamental and applied biological sciences. Psychology; Housing, Animal; locus coeruleus; Male; medial amygdala; Norepinephrine - biosynthesis; Norepinephrine - physiology; Rats; Rats, Sprague-Dawley; Receptors, Adrenergic, alpha-2 - metabolism; RNA, Messenger - biosynthesis; stress; Stress, Physiological - enzymology; Stress, Physiological - physiopathology; Tyrosine 3-Monooxygenase - biosynthesis; Tyrosine 3-Monooxygenase - genetics; tyrosine hydroxylase; Vertebrates: nervous system and sense organs; α 2a adrenoceptor
• ISSN: 0306-4522; 1873-7544
• DOI: 10.1016/j.neuroscience.2004.06.019

Chronic exposure to cold in rats alters the activity of locus coeruleus (LC) neurons. In this study we aimed to examine the cellular effect of cold stress on catecholamine neurons, and determine whether this is specific to the LC compared with other catecholamine cell groups. Male Sprague–Dawley rats were subjected to 21 days of isolation under ambient conditions, chronic cold exposure at 5 °C, or after chronic cold followed by return to ambient temperature for 7 or 14 days. In the LC, chronic cold exposure significantly reduced tyrosine hydroxylase (TH) mRNA expression by approximately 45% compared with control rats, and remained significantly reduced (approximately 36%) after return to ambient conditions for 7 days; however, expression returned to normal after 14 days' recovery. There were no significant changes in TH mRNA in the substantia nigra or ventral tegmental area. Chronic cold increased expression of α 2A adrenoceptor mRNA in the LC (approximately 27%). There were decreases in α 2A expression in the nucleus tractus solitarius; however, this was seen only in rats returned to ambient conditions for 7 days. Additionally, α 2A mRNA in the caudal ventrolateral medulla (A1 region) increased following cold exposure (approximately 84%) compared with controls. Binding of [ 125I]iodoclonidine to α 2-like protein increased in the olfactory bulbs but decreased in the medial amygdala following cold exposure. Collectively, these data indicate robust effects of cold on central catecholamine neurons, not necessarily specific to the LC.