[The mechanism of releasing and bio-behavioral significance of the hypothalamo-hypophyso-adrenal gland reaction to the environment (alarm reaction)].

Laboratory experimentation has demonstrated the large increase in the rate of circulating norepinephrin (N.E.), in a parallel with an improvement in cardiovascular dynamism of suprarenalectomized rabbits under the action of injection IV of hydrocortisone. As from this ascertainment, the author attempts to make a synthesis of known experimental facts demonstrating that next to a regulation in constancy (with negative retroaction) of the C.R.F. leads to A.C.T.H. leads to cortisol system, there exists a servomechanism (control external to the system) as from the activity of the nervous systems as compared with environment. Hydrocortisone favouring passive avoidance, and extinction facilitating the activity of the cholinergic inhibiting system of action (I.S.A.). A.C.T.H. facilitates active avoidance and the catecholaminergic activating system of action (A.S.A.). Now, it has already been demonstrated in the same laboratory that stimulation of I.S.A. or inhibition of the A.S.A. freed N.E. from the peripherous nerves of a adrenalectomized animal. It, therefore, seems that the early freeing of A.C.T.H. following aggression is capable of favouring locomotive activity (flight or fight). Should the latter be efficient, there is a return to the prior behavioural and endocrinal balance. On the other hand, should they be inefficient, there arises a vicious circle (regulation with tendency, positive retroaction) because secondary secretion of glucocorticoids will maintain inhibition of action and the secondary freing of the mineralocorticoids are discussed as well as the central mechanism of illness so called "psychosomatic".