1. Adult fowls (Gallus domesticus) with
cannulae chronically implanted into the IIIrd cerebral ventricle and various other sites of the brain received microinfusions or
injections of
catecholamines,
adenosine, 3',5'-cyclic
AMP or its dibutyryl derivative. The effects of these substances on behaviour, electrocortical activity and body temperature were studied.2. Behavioural and electrocortical sleep with fall in body temperature were obtained with intraventricular
noradrenaline,
alpha-methylnoradrenaline and
isoprenaline;
dopamine was ineffective. The doses required to elicit sleep were smaller than those affecting body temperature. Following
mebanazine, the effects of
noradrenaline were prolonged and doses of
dopamine, previously ineffective, lowered body temperature and induced behavioural and electrocortical sleep.3.
Noradrenaline,
alpha-methylnoradrenaline,
isoprenaline and
dopamine infused into the hypothalamus induced sleep and lowered body temperature. Effective doses of
noradrenaline,
alpha-methylnoradrenaline and
isoprenaline infused into the hypothalamus were one-twentieth to one-fifth those for
intraventricular injection. Tachypnoea developed with
isoprenaline and
dopamine. Additionally with
dopamine, there was deviation of the head to the contralateral side, together with repetitive jerking movements of the head. These effects were prolonged and intensified by
mebanazine, whereas the
involuntary movements with
dopamine were greatly reduced by
haloperidol.4.
Involuntary movements, but without sleep, were induced by infusing
dopamine into the paleostriatum augmentatum;
noradrenaline infused into this site was ineffective.5. In three of five fowls pretreated with
aminophylline, 3',5'-cyclic
AMP infused into the hypothalamus induced behavioural and electrocortical sleep; without
aminophylline pretreatment, 3',5'-cyclic
AMP was ineffective.
Adenosine infused into the hypothalamus, following pretreatment of fowls with
aminophylline, consistently induced behavioural and electrocortical sleep.
Dibutyryl cyclic AMP infused into the hypothalamus of intact fowls elicited behavioural arousal, followed by bursts of electrocortical spikes (6 Hz) over both cerebral hemispheres, spikes subsequently becoming regular at 1 Hz. Clonic limb and body movements occasionally accompanied the bursts of spike activity, infrequently developing into convulsions. In fowl encéphale isolé preparations, in which
dibutyryl cyclic AMP was infused into the hypothalamus, spike activity was confined to the ipsilateral hemisphere.