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Hemispherectomized pigeons were exposed daily to electrical footshocks delivered for 15 sec, at the same hour, for 8 weeks. Serial blood samples were obtained through a chronic vascular catheter. The adrenocortical response to chronic intermittent stress was measured kinetically at one week intervals. The initial response including several successive peaks(More)
Muscimol was chronically administrated to the third ventricle of thalamic pigeons by means of osmotic minipumps at the rate of 0.25 microgram X h-1 for 28 days. No abnormal behavioural sign was noted. The animals were subjected daily to chronic intermittent stress for the same 28-day period. Basal and stress-induced adrenocortical activities were evaluated(More)
The functioning of the hypothalamic pituitary-adrenocortical system was tested in young pigeons before and after hatching, by radiocompetitive assay of plasma corticosterone (B) at rest and under stress. 1 degree B was expressed in ng/ml. Resting adult values (8-10) could not be observed before the birds were 6 week-old. B levels were very low 36 h before(More)
Plasma corticosterone levels were determined by protein-binding assay at 2- and 5-min intervals after systemic or neurogenic stress. The same corticosterone (B) profile was observed after hemispherectomy as in intact pigeons, exhibiting episodic increase including several successive peaks after stress application. Hypothalamic stimulation of ACTH injection(More)
Thalamic and intact pigeons were equipped with a chronic arterial catheter and with a miniature electronic device for hypothalamic telestimulation. Chronic catheterization allowed for repetitive blood sampling in freely moving birds subjected to either systemic (ether inhalation) or neurogenic (electrical foot shocks) stress and to electrical stimulation of(More)
Exposure of control quail to low ambient temperature (4 degrees) for a short duration (15 min) led to a rapid increase in plasma thyroxine (T4) levels. A peak appeared 40 min after the cold began and was followed by a progressive and slow decline. T4 levels were elevated in birds maintained for up to 3 hr at 4 degrees. Restraint stress could be accompanied(More)
The corticotropic response to stress was studied by means of multiple unit activity (MUA) recording from the adrenocorticotropic region of the hypothalamus, and plasma corticosterone (B) determination. MUA was permanently obtained and B was measured at 2, then 5 and 10 min intervals before and after neurogenic (electrical shocks) or systemic (ether(More)
The role of diencephalic cholinergic neurotransmission in regulating hypothalamic-pituitary-adrenocortical (HPA) axis was investigated by means of administration of hemicholinium-3 (HC-3), a blocker of acetylcholine synthesis, in the third ventricle of hemispherectomized pigeons. Except for an early increase in ACTH and corticosterone levels following(More)
The thalamic pigeon was taken as a model to investigate mechanisms of adaptation to chronic intermittent stress. Muscimol was infused into the 3rd ventricle at the rate of 0.25 microgram.hr-1 by means of an osmotic minipump. In controls, pumps were filled in with saline. Animals were placed under constant light regimen and electrical foot shocks were(More)
Kinetic evaluation of the adrenocortical activation induced after hypothalamic stimulation was obtained by determining plasma corticosterone levels (protein binding assay) at 2, then 5 and 10 min intervals for 100 min. Chronic catheterization and an electronic miniature device for hypothalamic telestimulation allowed for avoiding any environmental(More)