Gabriel Osuide

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.

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.

Influence of levodopa, apomorphine and 3,4-dihydroxyphenylserine (DOPS) on strychnine-induced seizures in mice.

The effects of levodopa, apomorphine and 3,4-dihydroxyphenylserine (DOPS) on tonic seizures elicited by strychnine were investigated in mice. Levodopa (6.25-100 mg/kg), apomorphine (0.2-0.8 mg/kg) and FLA-63 (12.5 mg/kg) profoundly delayed the onset and reduced the incidence of strychnine seizures. In addition, these drugs decreased strychnine-induced mortality. DOPS (1-16 mg/kg) apparently shortened the onset of strychnine seizures and altered strychnine-induced mortality in a dose-dependent manner; low doses (1-2 mg/kg) enhanced while moderate doses (4-8 mg/kg) reduced the mortality rate. FLA-63 (12.5 mg/kg) potentiated the anticonvulsant effect of low doses of levodopa (6.25-12.5 mg/kg) while it had no significant influence on the anticonvulsant effect of higher doses (25-100 mg/kg) of levodopa. In addition, the onset of strychnine seizure was further delayed by FLA-63. Haloperidol (0.5 mg/kg) potentiated the convulsant effect of strychnine (1 mg/kg) as well as strychnine-induced mortality. It also antagonised the protective effect of levodopa (12.5 and 100 mg/kg) against strychnine (1 mg/kg). Phentolamine (5 mg/kg) and +/- propranolol (1 mg/kg) antagonised strychnine seizures. Strychnine-induced mortality was also reduced by these drugs. In addition, the effects of DOPS (2 mg/kg) on strychnine seizures were antagonised by phentolamine and propranolol. These results indicate that enhancement of dopaminergic and noradrenergic neurotransmission respectively attenuate and potentiate strychnine seizures in mice.

Behavioural effects of β,β′-iminodipropionitrile (IDPN) in the domestic fowl (Gallus domesticus)

Abstract 1. 1. The behavioural effects of ββ′-iminodipropionitrile (IDPN) were studied in chicks and adult fowls. 2. 2. Repeated administration of IDPN (75 mg/kg) for 5 days induced behavioural changes in chicks and adult fowls characterized by excitation, choreiform head and neck movements and circling (ECC-syndrome). 3. 3. Both acute and chronic administration of IDPN induced EEG desynchronization, EMG activation and enhancement of photic-evoked response (PER) in the hyperstriatum and pontine reticular formation while a decrease in PER was observed in the optic tectum. 4. 4. d-Amphetamine (2.5–5 mg/kg), apomorphine (0.1–0.25 mg/kg), piribedil (2.5–5 mg/kg), atropine (2.5–5 mg/kg), hyoscine (2.5–5 mg/kg) and cyproheptadine (0.5 mg/kg) potentiated the circling and choreiform head and neck movements. These activities were antagonized by pimozide (1 mg/kg), physostigmine (0.5 mg/kg) and quipazine (2.5–5 mg/kg). 5. 5. The results suggest that dopaminergic, serotoninergic and cholinergic mechanisms may be involved in IDPN-induced behavioural effects in chicks.

Influence of dopamine on strychnine-induced seizures in the domestic fowl (Gallus domesticus)

Abstract 1. 1. The influence of dopamine (DA) on strychnine seizures was studied using young chicks. 2. 2. The susceptibility of chicks to strychnine seizures decreased profoundly with age. 3. 3. DA protected the chicks against strychnine seizures dose-dependently. 4. 4. The anticonvulsant influence of DA against strychnine seizures decreased with the age of chicks. 5. 5. FLA-63 protected chicks against strychnine seizures. In addition, FLA-63 potentiated the anticonvulsant effect of DA against strychnine seizures. 6. 6. Pimozide effectively blocked the anticonvulsant effect of DA against strychnine seizures. 7. 7. Apparently, the anticonvulsant effect of DA against strychnine seizures in chicks might be mediated via activation of DA receptors.

Hypothermic effect of dopamine and l-dopa in the domestic fowl (Gallus Domesticus)

Abstract 1. 1. The thermal influence of dopamine (DA) and l -dopa was studied in chicks and adult fowls using a thermistor thermometer with rectal probes. 2. 2. DA produced a significant dose-dependent hypothermia in young chicks but did not exhibit any thermal effect in adult fowls. 3. 3. FLA-63 potentiated dopamine-induced hypothermia. 4. 4. The hypothermic effect of l -dopa in chicks and adult fowls was highly significant and dose-dependent; but was less pronounced in the latter. 5. 5. The hypothermic effect of both DA and l -dopa in young chicks was antagonised by pimozide. 6. 6. The results suggest that the hypothermic influence of DA and l -dopa might be mediated via activation of central DA receptors.

Effects of cimetidine on drug metabolism in rat pups

SummaryThe effects of Cimetidine on drug metabolism were studied in male and female rat pups and compared to similar effects in adult rats. As in adult rats, Cimetidine 50 mg/kg/day i.p for 7 days in the 2nd, 3rd, 4th or 5th weeks of life resulted in prolonged pentobarbitone sleeping times (diminished pentobarbitone hydroxylase activities), particularly when administered during the 3rd week. These effects of Cimetidine were reversible since they continued only up to 2 weeks in males and 4 weeks in females, but by the 6th week were no longer observed. Pretreatment with Cimetidine 15, 25 and 50 mg/kg/day i.p. for 7 days, resulted in a dose-dependent inhibition of aminopyrine N-demethylase and aniline hydroxylase as well as a prolongation of pentobarbitone sleeping time in both pups and adults, aniline hydroxylase being the least affected. In general, female pups were more adversely affected then male pups and adults. The therapeutic and toxicological relevance of these results in man are discussed.

Alteration of 5-hydroxytryptophan-induced hypothermia by serotonergic agents in the adult domestic fowl (Gallus domesticus)

Abstract 1. 1.|5-Hydroxytryptophan (5-HTP) induced a dose-dependent hypothermia in adult fowls. 2. 2.|The hypothermic effect of 5-HTP was potentiated by carbidopa, citalopram, additive with (±), (−) and (+) propanolol and antagonised by methysergide and metitepine. 3. 3.|Cyproheptadine, xylamidine and ketanserin did not antagonised 5-HTP-induced hypothermia. 4. 4.|The results suggest that the hypothermic effect of 5-HTP in fowls may be mediated mainly via activation of central 5-HT receptors, probably 5-HT 1 receptors.