Controlled clinical investigation of trimeprazine as a sleep-inducer in normal subjects

Evidence for histaminergic arousal mechanisms in the hypothalamus of cat

Polygraphic 23-hr recordings were carried out in 25 adult cats in order to examine the effects of both systemic and local injections of various histaminergic and antihistaminergic drugs on sleep-waking cycles. alpha-Fluoromethylhistidine (alpha-FMH), a specific inhibitor of histidine decarboxylase, when injected intraperitoneally at a dose of 20 mg/kg, induced a significant increase in deep slow wave sleep (S2) and a decrease in wakefulness (W), without modifying light slow wave sleep (S1) and paradoxical sleep (PS). Intraperitoneal injections of mepyramine (1 mg and 5 mg/kg), a well-known histamine H1-receptor antagonist, increased deep slow wave sleep and decreased wakefulness, as well as paradoxical sleep. Bilateral injections of alpha-FMH (50 micrograms/1 microliter) into the ventrolateral posterior hypothalamus, where histamine immunoreactive neurones have been recently identified, resulted in a significant decrease in wakefulness and increase in deep slow wave sleep. Similarly, injections of mepyramine (120 micrograms/1 microliter) in the same structures caused a significant decrease in wakefulness and an increase in deep slow wave and paradoxical sleep as well. In contrast, local injections of SKF-91488 (50 micrograms/1 microliter), a specific inhibitor of histamine-N-methyltransferase, led to a significant increase in wakefulness and decrease in both slow wave sleep (SWS) and paradoxical sleep. Injections of histamine, at doses of 5, 30 and 60 micrograms/1 microliter, also increased wakefulness and decreased slow wave sleep dose dependently, while these effects were completely blocked by pretreatment with mepyramine. The results suggest that histaminergic systems in the hypothalamus play an important role in arousal mechanisms and their actions are mediated through H1-receptors.

Effects of propiomazine on the EEG sleep of normal subjects

The effects of 25 mg propiomazine were examined in ten healthy volunteers in a sleep laboratory setting. A significant decrease in sleep latency and a corresponding decrement in subjectively assessed sleep latency was found during drug treatment. The distribution of the different sleep stages was affected to a relatively small extent. Some evidence for a suppression of REM-sleep in the early part of the treatment period was found. Based on subjective assessment, the subjects rated their sleep quality as significantly improved during treatment. Ratings of "drowsiness in the morning" were not different during baseline and drug treatment, but there was a significant decrease at withdrawal.

Effects of alpha-fluoromethylhistidine on sleep-waking parameters in rats

Effects of alpha-fluoromethylhistidine (FMH), an irreversible inhibitor of histidine decarboxylase, on the sleep-waking parameters were studied in rats for 24 hours. Intraperitoneal administration of FMH (100 mg/kg) at 11:30 hr resulted in a longer sleep latency compared with the control values. Hour-to-hour analyses revealed that wakefulness (W) time decreased (from 20:00 to 07:00 hr) and slow wave sleep (SS) time increased (from 19:00 to 06:00 hr) in the night. Paradoxical sleep (PS) time did not parallel the SS changes; it was increased significantly from 07:00 to 11:00 hr in the next morning. The influence of FMH seemed to be divided into direct, immediate action (increase of W) and late, prolonged action (decrease of W), and the results obtained support the histamine arousal hypothesis.

Effects of the beta-adrenoceptor antagonists acebutolol and metoprolol on sleep pattern in normal subjects

The effects of acute introduction and withdrawal of 2 new beta-adrenergic blockers, acebutolol and metoprolol, on sleep in normal subjects were investigated. Both the subjective effects of the drug and EEG sleep variables were determined during a baseline period with placebo and in relation to the drug. The results showed that neither drug had a significant effect on sleep pattern in normal subjects. However, a transient effect on certain sleep parameters was seen on the first night of drug administration, with complete return to baseline, on the following night without any evidence of rebound. Possible mechanisms to explain the central actions of beta-adrenergic blockers are briefly discussed.