THE ROLE OF THE DOPAMINERGIC SYSTEM IN SLEEP-WAKE REGULATION

Abstract

Aim: The Role of the Dopaminergic System in Sleep-Wake Regulation.

Material & Methods: The study was conducted at the sleep laboratory of the department of psychobiology with the approval of the ethics Committee of the university as well as the radiation protection center. Fifty healthy male volunteers ranging from 20 to 30 years of age were randomly assigned to one of three experimental groups after giving written informed consent (10 non-sleep deprived, 10 total sleep deprived, and 10 REM sleep deprived). During the week preceding the study as well as during the study period, participants were asked to abstain from alcohol, chocolate, and caffeinated beverages and to maintain a standardized bedtime schedule in accordance with their regular habits. Blood samples were collected every morning from each volunteer during the experimental protocol to evaluate if the sleep deprivation promoted changes in cortisol, prolactin, and estradiol levels (hormones related to dopaminergic activity and stress).

Results: (ROIs) for [99mTc] TRODAT-1 were used to estimate the concentration of DAT in the striatum (right and left at baseline) post SD, and post-sleep recovery. An elliptical ROI was placed on three consecutive slices in the occipital cortex, an area used for reference of non-specific DAT binding. The results show that after either 2 nights of total sleep deprivation or 4 nights of selective suppression of rem sleep, there were no statistical differences in prolactin, estradiol, and cortisol levels, as assessed by intra-group analysis.

Conclusion: We can’t exclude that the hormones assessed did not lose their periodic pattern of excretion during sleep loss. Since the volunteers were injected with a radioactive isotope to perform the speCt, additional blood samples to evaluate hormone levels were not recommended after this intervention.

Keywords: Dopaminergic system, Neurotransmitter, EEG, REM & NREM Sleep, Sleep Regulation