Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness and rapid eye movement (REM) sleep-related symptoms, such as cataplexy. The exact pathophysiology underlying the disease is unknown but may involve central cholinergic systems. It is known that the brainstem cholinergic system is activated during REM sleep. Furthermore, REM sleep and REM sleep atonia similar to cataplexy can be triggered in normal and narcoleptic dogs by stimulating cholinergic receptors within the pontine brainstem. The pontine cholinergic system is, therefore, likely to play a role in triggering cataplexy and other REM-related abnormalities seen in narcolepsy. The other cholinergic system that could be involved in the pathophysiology of narcolepsy is located in the basal forebrain (BF). This system sends projections to the entire cerebral cortex. Since acetylcholine release in the cortex is increased both during REM and wake, the basocortical cholinergic system is believed to be involved in cortical desynchrony. In the current study, we analyzed the effect of cholinergic compounds injected into the forebrain structures of narcoleptic and control dogs. We found that carbachol (a cholinergic agonist) injected into the BF triggers cataplexy in narcoleptic dogs while it increases wakefulness in control dogs. Much higher doses of carbachol bilaterally injected in the BF were, however, shown to trigger muscle atonia even in control dogs. These results suggest that a cholinoceptive site in the BF is critically implicated in triggering muscle atonia and cataplexy. Together with similar results previously obtained in the pontine brainstem, it appears that a widespread hypersensitivity to cholinergic stimulation may be central to the pathophysiology of canine narcolepsy.

The therapeutic potential of thyrotropin-releasing hormone (TRH) and TRH analogs in narcolepsy, a sleep disorder characterized by abnormal rapid eye movement (REM) sleep and daytime sleepiness, was examined using the canine model. The effects of TRH and the biologically stable TRH analogs CG3703, CG3509, and TA0910 on daytime sleep and cataplexy, a symptom of abnormal REM sleep, were assessed using polysomnographic recordings and the food elicited cataplexy test (FECT), respectively. CG3703 (100 and 400 g/kg, i.v.) and TA0910 (100 and 400 g/kg, i.v.) significantly increased wakefulness and decreased sleep in narcoleptic canines, whereas TRH (400 and 1600 g/kg, i.v.) had no significant effect. TRH (25-1600 g/kg, i.v.) and all three TRH analogs, CG3703 (6.25-400 g/kg, i.v., and 0.25-16 mg/kg, p.o.), CG3509 (25-1600 g/kg, i.v.), and TA0910 (25-1600 g/kg, i.v.), significantly reduced cataplexy in canine narcolepsy. These compounds did not produce any significant side effects during behavioral assays, nor did they alter free T 3 and T 4 levels in serum even when used at doses that completely suppressed cataplexy. Although more work is needed to establish the mode of action of TRH analogs on alertness and REM sleep-related symptoms, our results suggest a possible therapeutic application for TRH analogs in human sleep disorders.

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Objective:To determine the degree to which swallowing valproate (VP) tablets is an issue, the proportion of patients who would prefer an alternative formulation, and the predictors of preference.Methods:A quantitative telephone survey of eligible adults (n = 400, ≥18 years old) who currently take (n = 236) or previously took (n = 164) VP tablets within the past 6 months was conducted.Results:More than half of the patients indicated that VP tablets were ‘uncomfortable to swallow’ (68.5%, n = 274) and were ‘very interested’ (65.8%, n = 263) in medications that were easier to swallow. When choosing conceptually between taking VP tablet once/day or an equally safe and effective but significantly smaller soft gel capsule twice per day, the 82.8%, (n = 331) preferred the soft gel capsule. In the multivariate regression analysis, perceiving soft gel capsules to be easier to swallow (OR = 73.54; 95% CI = 15.01 to 360.40) and taking VP more frequently (OR = 2.02; 95% CI = 1.13 to 3.61) were significant predictors of soft gel capsule treatment preference.Conclusion:VP users would prefer a formulation that is easier to swallow, even if it is needed to be taken twice per day. When choosing between medications with similar efficacy and safety, physicians can consider patient preferences to optimize conditions for medication adherence.