Les troubles du sommeil, tels que la somnolence diurne excessive et les attaques narcoleptiques, sont fréquemment observés chez les patients Parkinsoniens. Malgré de nombreux efforts cliniques à l’échelle mondiale, il reste à déterminer si ces troubles sont causés par les lésions neuronales dopaminergiques (DAergiques) ou non DAergiques, par les troubles moteurs ou par les effets délétères des médicaments anti-parkinsoniens. Par une approche pluridisciplinaire (analyse EEG; mesure de l’activité locomotrice; tests pharmacologiques; immunohistochimie) chez le félin traité au MPTP, nous avons étudié la corrélation possible entre perte DAergique et troubles du cycle veille-sommeil (V/S). Le MPTP (5mg/kg/jour x5, i.p.) induit en période aiguë, une hypersomnie en sommeil lent (SL), une suppression du sommeil paradoxal (SP), ainsi qu’une diminution de la locomotion et une difficulté à l’initiation des mouvements. Les agonistes DAergiques (L-dopa; ropinirole) empêchent l’hypersomnie en SL de façon transitoire. Durant la période chronique, les taux d’éveil et de SL reviennent à la normale. Le SP augmente transitoirement et s’associe à des épisodes narcoleptiques. Les analyses ex-vivo révèlent une diminution du marquage TH (corps cellulaire de la substance noire ; fibres du striatum). Le marquage des neurones cholinergiques (cerveau antérieur basal et tegmentum mésopontique) semblent inchangée. Nos résultats montrent donc que le MPTP induit chez le félin des symptômes moteurs et des troubles du sommeil proches de ceux observés chez les patients parkinsoniens. Cette étude suggère également une corrélation possible entre les troubles du cycle V/S et la perte des cellules DAergiques / Motors disorders are not the only symptoms of Parkinson disease (PD), and sleep disorders such as somnolence and narcolepsy are frequently reported in PD patients. Despite much investigation worldwide, it remains unknown whether these disorders are caused by dopaminergic (DArgic), non-DArgic neural lesions, nocturnal motor disability or deleterious effect of anti-PD drugs. Using multiple experimental approaches (EEG and sleep-wake recordings/pharmacological dosing / immunohistochemistry) in cats treated with MPTP, which causes DArgic neuronal loss, we have studied the possible correlation between the induced effects on the sleep-wake (S/W) cycle and those on DArgic neurons. MPTP (5mg/kg/day x 5, i.p.) caused, during the acute period, a slow wave sleep hypersomnia (SWS, up to 80% of recorded time) and a suppression of paradoxical sleep (PS), accompanied with pronounced behavioural somnolence, marked decrease in locomotion and difficulty to initiate movements. DArgic agonists L-dopa and ropinirole transiently prevented hypersomnia in SWS. During the chronic period, whereas the amount of W and SWS returned to control, PS transiently increased, associated with narcolepsy-like episodes. Ex-vivo analyses revealed marked decrease in TH labelling (cell bodies in the substantia nigra and terminal-like dots in the striatum) whereas cholinergic neurons in the basal forebrain and mesopontine-tegmentum seemed unchanged. Thus, MPTP treated cats showed major signs of motor and S/W disorders similar to those seen in PD patients and so could serve as useful animal model. Our results also suggest a possible correlation/causality between the MPTP-induced S/W disorders and DArgic cell loss.

The aim of this study was to investigate the causes of learner dropout in secondary schools around Johannesburg South, Gauteng Province. Twenty-seven participants from three secondary schools in Orange Farm area were purposively sampled for the study. A qualitative design was used. In-depth interviews were conducted to collect data to allow the researcher a platform to ask open-response questions and to explore the participants’ perspectives about the causes of learner dropout. The data was analysed thematically by carefully identifying and describing significant themes that emerged from educators, learners, parents, SGB chairpersons and principal’s responses to interview questions. The study revealed that teenage pregnancy, lack of parental involvement, substance abuse and peer pressure, among others, were the causes of learner dropout. The study recommends that schools put more efforts on abstinence programs, sex education and the use of contraceptives such as condoms, pills and injectables; training of educators on the management of drugs and pregnancy, and resuscitation of extra-mural activities. Recommendations for further research were made. / Inclusive Education / M. Ed. (Inclusive Education)

The aim of this study was to investigate the causes of learner dropout in secondary schools around Johannesburg South, Gauteng Province. Twenty-seven participants from three secondary schools in Orange Farm area were purposively sampled for the study. A qualitative design was used. In-depth interviews were conducted to collect data to allow the researcher a platform to ask open-response questions and to explore the participants’ perspectives about the causes of learner dropout. The data was analysed thematically by carefully identifying and describing significant themes that emerged from educators, learners, parents, SGB chairpersons and principal’s responses to interview questions. The study revealed that teenage pregnancy, lack of parental involvement, substance abuse and peer pressure, among others, were the causes of learner dropout. The study recommends that schools put more efforts on abstinence programs, sex education and the use of contraceptives such as condoms, pills and injectables; training of educators on the management of drugs and pregnancy, and resuscitation of extra-mural activities. Recommendations for further research were made. / Inclusive Education / M. Ed. (Inclusive Education)