Possible Anxiolytic Effects of Ivermectin in Rats

Ivermectin, a mixture of 22,23-dihydroavermectin B_1a (80%) and B_1b (20%), is produced by Streptomyces avermectilis, an actinomycete. It is a macrocyclic lactone disaccharide, a member of the avermectin family, and is used as an antiparasitic drug. Previous studies performed in our laboratory showed that doramectin, another avermectin drug, interferes with GABAergic-related behaviours, leading to anxiety and seizures. The objective of the present study was to examine the effects of ivermectin (0.5 and 1.0 mg/kg) on the central nervous system of rats, using behavioural models related to GABAergic neurotransmission. A known anxiolytic drug, diazepam, was used as a positive control. Open field and elevated plus-maze behaviours, as well as conflict behaviour to a conditioned response, were assessed. The effects of ivermectin and diazepam in reversing the anxiety induced by picrotoxin was studied. The protective effects of ivermectin on pentylenetetrazole- and picrotoxin-induced seizures were also investigated. In the open field, 1.0 mg/kg ivermectin decreased locomotion frequency at 15 and 60 min of observation, rearing behaviour showed a biphasic effect at 15 and 30 min and duration of immobility was increased in all sessions after 1.0 mg/kg ivermectin. These data suggest anxiolytic or sedative effects. Ivermectin and diazepam both had a tendency to cause an increase both in the number of entries into the open arms and on the time spent in the open arms of an elevated plus-maze. Picrotoxin on its own reduced the number of entries as well as the time spent in the open arms. Both diazepam and ivermectin reversed these effects of picrotoxin. In conflict behaviour analysis, ivermectin and diazepam gave the classic effect of an anxiolytic drug, reversing the conditioned response to shock. Ivermectin protected rats from the convulsant effects of pentylenetetrazole but not from those of picrotoxin. Thus, ivermectin had the pharmacological profile of an anxiolytic drug with GABAergic properties. The lack of effect on seizures induced by picrotoxin suggests that the action of ivermectin is different from that of the benzodiazepine drugs.     

INADVERTENT INTRATHECAL ADMINISTRATION OF DIATRIZOATE MEGLUMINE AND DIATRIZOATE SODIUM DURING MYELOGRAPHY IN A DOG

A dog undergoing diagnostic myelography inadvertently received 0.5 ml diatrizoate meglumine (66%) and (10%) diatrizoate sodium via intrathecal injection. This resulted in post-operative seizures requiring extended sedation of the patient. The clinical course and management of this patient are presented. Complications associated with the inappropriate administration of a hyperosmolar contrast agent into the subarachnoid space and the results of similar accidents in humans are also discussed. The dog in the report recovered with no evidence of long trem neurological dam     

Suspected venous air embolism in three horses

Venous air embolism was suspected in 3 hospitalised horses on the basis of an inadvertently open jugular venous line. Subsequently the 3 horses developed clinical signs including cardiovascular collapse, cardiac dysrhythmia, pulmonary oedema, behavioural abnormalities and neurological signs consistent with central nervous system injury. Treatment included intranasal oxygen therapy, i.v. fluid administration and anti‐inflammatory therapy. Specific therapy aimed at treating air embolism in man is reviewed, with pertinent therapy potentially applicable to horses emphasised.     

基于强占优先权的等待制M/M/n排队模型研究

文章首先研究了只有一类顾客的具有强占优先权的等待制M/M/n排队模型的顾客平均逗留时间和平均排队等待时间.在此基础上进一步研究了具有两级顾客到达的具有强占优先权的等待制M/M/n排队模型,得出了两级顾客的平均逗留时间和平均排队等待时间.