Chronic stress decreases the expression of sympathetic markers in the pineal gland and increases plasma melatonin concentration in rats.
Chronic stress affects brain areas involved in learning and emotional responses. Although most studies have concentrated on the effect of stress on limbic-related brain structures, in this study we investigated whether chronic stress might induce impairments in diencephalic structures associated with limbic components of the stress response. Specifically, we analyzed the effect of chronic immobilization stress on the expression of sympathetic markers in the rat epithalamic pineal gland by immunohistochemistry and western blot, whereas the plasma melatonin concentration was determined by radioimmunoassay. We found that chronic stress decreased the expression of three sympathetic markers in the pineal gland, tyrosine hydroxylase, the p75 neurotrophin receptor and alpha-tubulin, while the same treatment did not affect the expression of the non-specific sympathetic markers Erk1 and Erk2, and glyceraldehyde-3-phosphate dehydrogenase. Furthermore, these results were correlated with a significant increase in plasma melatonin concentration in stressed rats when compared with control animals. Our findings indicate that stress may impair pineal sympathetic inputs, leading to an abnormal melatonin release that may contribute to environmental maladaptation. In addition, we propose that the pineal gland is a target of glucocorticoid damage during stress.
Dagnino-Subiabre
Alexies
A
Department of Psychiatry and Center for Medical Research, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile.
Orellana
Juan A
JA
Carmona-Fontaine
Carlos
C
Montiel
Juan
J
Díaz-Velíz
Gabriela
G
Serón-Ferré
María
M
Wyneken
Ursula
U
Concha
Miguel L
ML
Aboitiz
Francisco
F
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002908:Chronic Disease; D015536:Down-Regulation / Q000502:physiology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005986:Glyceraldehyde 3-Phosphate / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008550:Melatonin / Q000097:blood* / Q000378:metabolism; D009043:Motor Activity / Q000502:physiology; D010870:Pineal Gland / Q000294:innervation / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020800:Receptor, Nerve Growth Factor / Q000378:metabolism; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000097:blood* / Q000503:physiopathology; D017779:Sympathetic Fibers, Postganglionic / Q000378:metabolism / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000378:metabolism* / Q000503:physiopathology; D014404:Tubulin / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology
D015415:Biomarkers; D020800:Receptor, Nerve Growth Factor; D014404:Tubulin; D005986:Glyceraldehyde 3-Phosphate; D014446:Tyrosine 3-Monooxygenase; D048049:Extracellular Signal-Regulated MAP Kinases; D008550:Melatonin