The disposition of sympathetic transmitter within the wall of rat femoral and rabbit saphenous arteries has been studied during sympathetic stimulation. Using a histochemical fluorescence technique, sharply delineated bead-like fluorescent spots representing sympathetic nerve terminals were found at the adventitiomedial junction. In specimens excised during sympathetic nerve stimulation, the entire media was veiled by fluorescent material representing noradrenaline which had diffused into that layer after release. The localization of the nerve terminals in controls as well as diffusion of transmitter during stimulation in the rat femoral artery was corroborated by autoradiography of tritiated noradrenaline.
In the current experiment, we used the saccadometric test to study the effect of a single therapeutic dose of methadone on the integrity of cortico-subcortical brain functioning. In this prospective study, we used the Saccadometer System (Advanced Clinical Instrumentation, Cambridge, UK). The saccadometric test was performed before and 1.5 hours after methadone dosing. We analyzed the following saccadic parameters: latency, duration, amplitude, average and peak velocity, and processing performance (promptness) as well as a number of different types of saccades (like correct/incorrect, under/overshoot, and left-sided/right-sided). The sample consists of 40 subjects with an average 18 years of opioid addiction. The mean age is 35.3 ± 7 (80% males and 20% females). The mean period of heroin dependence is 15.3 ± 6.3 years. The mean daily dose of methadone in substitution therapy is 90 ± 26.5 mg. After administration of a single therapeutic dose of methadone, there were statistically significant differences in the values of saccade duration and latency when compared to the values before the drug administration. Average duration of saccade was significantly longer [51.40 ± 8.75 ms versus 48.93 ± 6.91 ms, z = 2.53, p = .01] and average latency was significantly longer [198.85 ± 52.57 ms versus 183.05 ± 30.95 ms, z = 2.09 p < .03]. This is the first study to test the therapeutic effect of daily methadone dosing on the integrity of the cortico-subcortical brain functions as measured by the saccadometry. More research is needed to explore the effect of illicit opioid use on the integrity of brain structures and functions, and the protective effect of opioid agonist therapy on reversing the damaging effects of illicit opioid use.
Background and Objectives: Evidence suggests that methadone may play a protective role in the faulty decision-making in heroinaddicted individuals. This may reduce craving for opioids and the risky decisions associated with active opioid use. Methods: We tested the effect of a daily therapeutic dose of methadone on faulty decision-making in eighty (n ¼ 80) individuals with a history of opioid addiction. We used the Iowa Gambling Task (IGT) and compared the score and response time before and after the daily methadone dosing. Results: The mean net IGT score before methadone dose was 10 (AE22) and 22 (AE23) after methadone dose (t ¼ 4.23, p ¼ .00006). These results reflect statistically significant improvement in faulty decisions after the administration of the daily methadone dose.The mean response time for the reward cards before methadone dose were 1,856 ms (AE871) and 1,465 ms (AE851) after methadone dose (t ¼ 2.55, p ¼ .012). The mean response time for the punishment cards before methadone dose were 1,688 ms (AE911) and 1,399 ms (AE827) after methadone dose (t ¼ 1.86, p ¼ .065). These results reflect statistically significant improvement in response time to a rewarding healthy decisions after the administration of the daily methadone dose. Conclusions and Scientific Significance: This is the first study to report the effect of a therapeutic dose of methadone on improving faulty decisions for individuals with a long history of opioids addiction. This study demonstrated that the time to making a healthy decision was significantly shorter as a result of administration of methadone. (Am J Addict
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