Effects of some centrally-acting drugs in conscious chicks and on spinal reflexes

Influence of dopamine, levodopa and apomorphine on maximal electroconvulsive seizure in the domestic fowl (Gallus domesticus)

The influence of dopamine, levodopa and apomorphine on maximal electroconvulsive seizure was studied in young chicks, adult cocks and rats. The susceptibility of chicks to maximal electroshock seizure increased with age between 1 to 7 days. Low to moderate doses of dopamine (12.5-150 mg/kg, i.p.), levodopa (6.25-25 mg/kg, s.c.) and apomorphine (0.25-2.0 mg/kg, s.c.) significantly (P less than 0.005) protected chicks against electroshock seizure, while high doses (200-400 mg/kg, i.p. of dopamine, 50-200 mg/kg, s.c. of levodopa and 2.5-5 mg/kg, s.c. of apomorphine) enhanced electroshock seizure in 1 to 7 day old chicks. However, when 14 day old chicks were used, these dopaminoceptor agonists protected the chicks against maximal electroshock seizure. Noradrenaline (1-40 mg/kg, i.p.) had no significant effect on electroshock seizure in chicks. Both pimozide (4 mg/kg, i.p.) and haloperidol (0.4 mg/kg, i.p.) antagonized the effects of levodopa (12.5 and 50.0 mg/kg, i.p.) and apomorphine (0.5-5 mg/kg, s.c.) on maximal electroshock seizure. The seizure susceptibility of both adult rats and fowls to electroshock was not altered by dopamine (12.5-400 mg/kg, i.p.). Central dopamine neurotransmission might be involved in the biphasic dose-dependent effects of dopamine, levodopa and apomorphine on maximal electroshock seizure in young chicks.

Ontogeny of behavioral sensitivity to glycine in the chick embryo

Strychnine (STR), glycine (GLY), and gamma-aminobutyric acid (GABA) were injected intravenously into 6- and 7-day chick embryos and subsequent effects upon spontaneous motility were observed. In 7-day embryos STR alone increased motility and when injected simultaneously with GLY antagonized the GLY-induced motility decrements; STR did not antagonize GABA-induced motility decrements. In 6-day embryos STR injected alone had no effect on motility, but did antagonize motility decrements induced by the simultaneous injection of GLY; again STR did not antagonize GABA-induced motility decrements.

Behavioral and electroencephalographic manifestations of avian epilepsy: a review of the literature

Recently, electrophysiological studies on sleep and wakefulness in birds have yielded useful results. Furthermore, recent evidence obtained in behavioral and electroencephalographical investigations of epileptic birds, induced neuropharmacologically or genetically, have led to recognition of the fact that epileptic seizures are present in aves, and that these seizures reveal many similarities between mammalian and avian epilepsy. While the investigation of birds is of obvrious value for demonstrating the neuropharmacological interrelationship with the brain, comparison of the correlation between abnormal behavior and the electroencephalogram in birds and higher vertebrates requires further research. In the present paper, normal and abnormal electroencephalographic activity associated with behavior of birds is reviewed. It was concluded that birds provide a useful preparation for studying experimental epilepsy.

Effects of gamma-hydroxybutyrate on chick behaviour, electrocortical activity and crossed extensor reflexes

1. Convulsant and anticonvulsant effects of gamma-hydroxybutyrate (GHB) have been studied in chicks.2. When administered alone, GHB produced weak myoclonic seizures accompanied by electrocortical synchrony and spikes.3. GHB was found to protect chicks against leptazol- and picrotoxin-induced seizures. A slight potentiation of strychnine-induced seizures was evident.

Pharmacological properties of amino-oxyacetic acid in the chicken

1. The effects of amino-oxyacetic acid (AOAA) on the central nervous system and on skeletal muscle have been examined in the chicken.2. AOAA had both anticonvulsant and convulsant effects, depending on the dose, as in other species.3. The convulsant effect, accompanied by EEG spiking, decreased rapidly with increase in age of young chicks.4. The convulsant effect was exerted primarily through supraspinal centres.5. Of control depressants tested, only troxidone and small doses of AOAA afforded significant protection against AOAA seizures.