Objective: To study nystagmus in harmaline induced tremor (HIT) in rats.

Background: Clinical observations have shown the presence of nystagmus in some patients with essential tremor (ET). HIT is an animal model for ET. Ethanol attenuates both ET and HIT. Investigations were undertaken to study the presence of nystagmus in HIT and the effect of ethanol.

Methods: Male Sprague Dawley rats were divided into three groups of ten and harmaline was administered (20 mg/kg, i.p) to induce tremor. Group 1 weighed between 100 ± 10 g, group 2 weighed 225 ± 15g, and group 3 weighed 350 ±15 g. The onset of tremor was recorded and the animals were continuously monitored for nystagmus with a scale of 0-4. Nystagmus was recorded with a video camera. Ten minutes after developing nystagmus, ethanol (8mL/kg orally), was administered to the HIT rats and they were then observed for 20 minutes.

Results: The results of our study showed the occurrence of nystagmus in HIT rats. Nystagmus was not observed in group 1 (0/10), but was seen in both group 2 (4/10) and in group 3 (9/10). The severity of nystagmus varied from animal to animal. The intensity of nystagmus was significantly attenuated upon treatment with ethanol.

Conclusions: To our knowledge, this is the first report to show attenuation of nystagmus in rats with harmaline-induced tremor following oral ethanol administration. These observations further strengthen the use of HIT as a valuable model for studying ET. However, further studies are warranted to better understand the mechanism of nystagmus in HIT rats.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/nystagmus-in-harmaline-induced-tremors-in-rats-and-attenuation-with-ethanol/