Independent GABAergic and cholinergic modulation of apomorphine-induced stereotyped rearing in the rat.

The injection of GABA into the caudate nucleus inhibited the stereotyped rearing induced by apomorphine in a dose-related manner. Muscimol, a potent GABAergic agonist shared this effect. The inhibitory effect of GABA was easily counteracted by bicuculline but not by pretreatment with atropine.

Recrystallization from ether causes unusual changes in the convulsant activity of pentylenetetrazol.

The convulsant activity of commercial pentylenetetrazol (PTZ) and that of pentylenetetrazol recrystallized from ether (PTZE) were compared in the waking rabbit by means of recording the electrical activity of the brain. In addition, the interaction between the two substances was studied. When given in slow intravenous infusion, PTZE proved only half as effective as PTZ (threshold doses: 23.

Effect of (D-Met2, Pro5)enkephalinamide, a highly potent opiate agonist, on the drinking behaviour of rats.

The highly potent opiate agonist, (D-Met2, Pro5)enkephalinamide, markedly influenced drinking behaviour of the rat. It inhibited the drinking caused by water deprivation, the drinking response to intracerebroventricular application of angiotensin-II, as well as the drinking evoked by systemic administration of isoprenaline. The compound investigated was effective not only upon intracerebroventricular injection but also upon systemic application.

Cholinergic and catecholaminergic interaction and fluid intake in the rat.

The effect of simultaneous topical application of adrenergic agonists was investigated on the polydipsia caused by direct carbachol (CCh) stimulation of the rat brain. In addition, fluid selection (4-choice arrangement) was studied. Noradrenaline and isoprenaline fully antagonized the CCh effect after either intracerebroventricular, intraseptal or intrapreoptic application.

Atropine stereotypy and its inhibition by intracaudate triperidol in the rat.

One component (rearing) of the stereotyped behavior of the rat was quantitated using erigometer, a new device developed in this laboratory. Intraperitoneal injection of atropine, but not methylatropine, caused dose-related stereotyped behavior in the rat and this effect was antagonized by intracaudate injection of triperidol in a dose-related manner. It is concluded that stereotypy can be evoked also in the case when the striatal dopaminergic tone is normal or even below normal: it is the equilibrium of the striatal cholinergic-dopaminergic systems which must be shifted towards dopamine, which is necessary for the development of this behavioral manifestation.

Adrenergic modulation of a cholinergic emotional reaction in the cat's thalamus.

Direct carbachol stimulation of the intralaminar nuclei of the thalamus evokes an affective defense reaction in the cat. Pretreatment of the region with noradrenaline inhibited the reaction in a dose-related manner. Phenylephrine was ineffective in this respect while isoprenaline exhibited roughly the same inhibitory action as noradrenaline.

Septum-lesioned rats in pharmacological investigations: a re-evaluation.

An objective and quantitative method has been developed for measuring the hyper-reactivity of septum-lesioned rats. Twenty drugs belonging to various classes have been investigated as to their influence on this hyper-reactivity. Seventeen compounds inhibited septal hyperreactivity.