Neonatal asphyxia under hyperthermic conditions alters HPA axis function in juvenile rats.
Neonatal anoxia is an example of early-life threatening experience that might exert long-lasting behavioral disturbance. One of the consequences of neonatal asphyxia is hyperactivity in open-field test. Changes in open-field activity are coupled with changes in the function of the hypothalamic-pituitary-adrenal (HPA) axis. A critical determinant of the severity of hypoxic-ischemic brain injury in newborn rats is body temperature. Hyperthermia under anoxic conditions increases locomotor activity in the open-field test. Therefore, the aim of the present study was to test whether body temperature during neonatal anoxia can affect basal and stress-induced corticosterone secretion in rats. At the age of 2 days Wistar rat pups were exposed to anoxia in 100% nitrogen atmosphere. Rectal temperature was kept at 33 degrees C (typical for the rat pups), or was elevated to a level typical for febrile adults (39 degrees C). Control rats were exposed to atmospheric air under the respective thermal conditions. Basal and stress-induced corticosterone levels were assessed using sulphuric acid-induced fluorescence, on postnatal day 14. Body temperature during neonatal asphyxia altered the early developmental profile of plasma corticosterone. Hyperthermia under anoxic conditions decreased the corticosterone response to open-field stress. In conclusion, febrile body temperature changes corticosterone release, which might induce neurobehavioral disturbances. On the other hand, a protection against the HPA dysfunction can be achieved by the reduced physiological neonatal body temperature.
Rogalska
Justyna
J
Department of Animal Physiology, Institute of General and Molecular Biology, N. Copernicus University, ul. Gagarina 9, 87-100 Toruń, Poland. rogal@umk.pl
Caputa
Michał
M
D000818:Animals; D000831:Animals, Newborn; D003345:Corticosterone / Q000097:blood / Q000378:metabolism; D005334:Fever / Q000150:complications / Q000503:physiopathology*; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology*; D000860:Hypoxia / Q000150:complications / Q000503:physiopathology*; D010913:Pituitary-Adrenal System / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar
D003345:Corticosterone