No abstract

No abstract

No abstract

In order to find out the possible earliest biomarkers of Parkinson's disease (PD) cholinopathy, we followed the impact of bilateral pedunculopontine tegmental nucleus (PPT) lesion in rat on: the cortical and hippocampal sleep/wake states architectures, all sleep states related EEG microstructures, sleep spindles, the basal and stimulated locomotor activity. Sleep and basal locomotor activity in adult Wistar rats were followed during their inactive circadian phase, and throughout the same aging period. The bilateral PPT lesions were done by 0.1M ibotenic acid (IBO) during the surgical procedure for implantation of the electroencephalographic (EEG) and electromyographic (EMG) electrodes for chronic sleep recording. The cholinergic neuronal loss was identified by NADPH - diaphorase histochemistry. After all sleep and behavioral recording sessions, the locomotor activity was stimulated by d-amphetamine (d-AMPH) and the neuronal activity of striatum was followed by c-Fos immunolabeling. Impaired cholinergic innervation from the PPT was expressed earlier as sleep disorder then as movement disorder, and it was the earliest and long-lasting at hippocampal and thalamo-cortical level, and followed by a delayed "hypokinesia". This severe impact of a tonically impaired PPT cholinergic innervation was evidenced as the cholinergic interneuronal loss of the caudate putamen and as a suppressed c-Fos expression after stimulation by d-AMPH. In order how they occurred, the hippocampal non rapid eye movement (NREM) sleep disorder, altered high voltage sleep spindle (HVS) dynamics during rapid eye movement (REM) sleep in the hippocampus and motor cortex, and "hypokinesia" may serve as the biomarkers of PD cholinopathy onset and progression.

Our previous studies in the rat model of Parkinson’s disease (PD) cholinopathy demonstrated the sleep-related alterations in electroencephalographic (EEG) oscillations at the cortical and hippocampal levels, cortical drives, and sleep spindles (SSs) as the earliest functional biomarkers preceding hypokinesia. Our aim in this study was to follow the impact of a unilateral substantia nigra pars compacta (SNpc) lesion in rat on the cortical and hippocampal sleep architectures and their EEG microstructures, as well as the cortico-hippocampal synchronizations of EEG oscillations, and the SS and high voltage sleep spindle (HVS) dynamics during NREM and REM sleep. We performed unilateral SNpc lesions using two different concentrations/volumes of 6-hydroxydopamine (6-OHDA; 12 μg/1 μl or 12 μg/2 μl). Whereas the unilateral dopaminergic neuronal loss >50% throughout the overall SNpc rostro-caudal dimension prolonged the Wake state, with no change in the NREM or REM duration, there was a long-lasting theta amplitude augmentation across all sleep states in the motor cortex (MCx), but also in the CA1 hippocampus (Hipp) during both Wake and REM sleep. We demonstrate that SS are the hallmarks of NREM sleep, but that they also occur during REM sleep in the MCx and Hipp of the control rats. Whereas SS are always longer in REM vs. NREM sleep in both structures, they are consistently slower in the Hipp. The dopaminergic neuronal loss increased the density of SS in both structures and shortened them in the MCx during NREM sleep, without changing the intrinsic frequency. Conversely, HVS are the hallmarks of REM sleep in the control rats, slower in the Hipp vs. MCx, and the dopaminergic neuronal loss increased their density in the MCx, but shortened them more consistently in the Hipp during REM sleep. In addition, there was an altered synchronization of the EEG oscillations between the MCx and Hipp in different sleep states, particularly the theta and sigma coherences during REM sleep. We provide novel evidence for the importance of the SNpc dopaminergic innervation in sleep regulation, theta rhythm generation, and SS/HVS dynamics control. We suggest the importance of the underlying REM sleep regulatory substrate to HVS generation and duration and to the cortico-hippocampal synchronizations of EEG oscillations in hemiparkinsonian rats.