Objective To observe the efficacy,safety and optimum dose of pramipexole in treating patients with essential tremor (ET).Methods Patients in line with diagnostic criteria of essential tremor (ET),collected in our hospital from May 2011 to December 2012,were chosen in our study.Registration and follow-up files were established and a five-week treatment with pramipexole was routinely given to these patients:week 1:0.25 mg/d (0.125 mg bid),week 2:0.375 mg/d (0.125 mg rid); week 3:0.5 mg/d(0.25 mg bid),and week 4:0.75 mg/d (0.25 mg tid); dose adjustment was based on the rating scale for ET of the National Institutes of Health of United States and the subjective feelings of the patients after treatment with pramipexole every week; all patients were required to increase the amount of pramipexole at week 2; if the effect was the same as before in referral at week 3 by increasing the amount of pramipexole,increasing the amount was not needed; otherwise,increasing the amount was continued until the tremor symptoms was no longer worsen.The amount of some patients could be increased to 1.5 mg/d (0.5 mg tid) at week 5.At week 6,the efficacy and dose of all patients were evaluated and recorded to analyzed the treatment efficacy and optimum dose; treatment emergent symptom scale (TESS) was employed to assess the side effects.Results Forty six patients completed the study; symptom relief was noted in 45 patients with a total efficacy rate reaching 97.83％.An obvious statistical difference existed in the differential daily dose of Pramipexole (x2=32.473,P=0.000); an obvious statistical difference existed between the dose of 1.5 mg/d (0.5 mg tid) and others doses (P＜0.05).The most common side effects were hallucination,dizziness and orthostatic hypotension,but disappeared with the drug reduction or withdrawal; no patient gave up treatment resulting from the side effect.Conclusion Pramipexole is highly effective and safe in the treatment of patients with ET; the suitable effective dose is 1.5 mg/d (0.5 mg tid); it can be used as the first-line treatment for ET.

Objective:To study the distribution and changes of dopamine transporter (DAT) in guinea pig eyes under different light patterns.Methods:Thirty-six 3-week-old white ordinary-grade guinea pigs were randomly selected and divided into groups of 10 000 lx, 5 000 lx, and 500 lx, with 12 guinea pigs in each group exposed to strong light, medium strong light, and normal light, respectively.Each group was randomly divided into 3 subgroups, with 4 guinea pigs in each subgroup.The 3 subgroups of 500 lx group received light exposure for 5, 20, and 40 minutes, respectively.The 3 subgroups of 5 000 lx group received light exposure for 2, 4, and 40 minutes, respectively.The 3 subgroups of 10 000 lx group received light exposure for 2, 5, and 20 minutes, respectively.After light treatment, each group of guinea pigs was injected with 99mTc-TRODAT-1 for SPECT DAT imaging, and image data were collected by Micro-SPECT.The region of interest (ROI) of guinea pig retinas was analyzed using Micro-CT software.The counts of ROI were expressed as Sum, which reflected the relative distribution or density of DAT.The DAT density between experimental and control eyes of guinea pigs after light exposure, the differences in DAT density between guinea pig eyes under different light intensities, the differences in DAT density between guinea pig eyes after different light durations, and the cumulative and interactive effects of light intensity and light duration on DAT aggregation in guinea pigs were compared.Another 3 guinea pigs were selected, and after light exposure, the 3 guinea pigs' eyes underwent continuous image acquisition for 6 hours at 20-minute intervals, and 18 images per guinea pig were acquired to analyze the trend of DAT density in guinea pig eyes over time.This study was approved by the Ethics Committee of Shanghai General Hospital (No.2020SQ196). Results:The DAT density (Sum value) of experimental eyes at 500, 5 000, and 10 000 lx were 5 598.97±3 159.38, 8 636.78±2 503.16, and 7 407.39±2 053.41, respectively, significantly higher than 4 388.89±2 902.90, 5 981.92±3 057.44, and 5 091.32±2 039.36 of control eyes ( t=5.31, 4.69, 11.80; all at P<0.001). At 500 lx, there was a statistically significant difference in DAT density between the experimental and control eyes of guinea pigs at different light exposure durations ( F=14.01, P<0.01), while no significant difference was found at other light intensities at different light exposure durations (both at P>0.05). When the light exposure time was 5 minutes, the difference in DAT density between the experimental and control eyes of guinea pigs was significantly greater in the 10 000 lx group than in the 500 lx group ( t=-13.22, P<0.001). There was no statistically significant difference between different groups at other light exposure durations (all at P>0.05). No cumulative or interactive effects of light intensity and light duration were found on the differences in DAT density (all at P>0.05). Continuous scanning after illumination showed that DAT density in guinea pig retinas first increased to a peak over time and then gradually returned to normal values. Conclusions:Light, even under moderate or normal light levels, can cause an increase in the secretion of DAT in the retina and stimulate the production of DAT.Light intensity and duration have no cumulative or interactive effects on the distribution and density of retinal DAT.