Search PubMed⌕ Search

Biomedical subjects

M Radulovacki

Publications and source records attributed to M Radulovacki.

90 records · Page 5Linked to original sources
PubMed1976

Effects of methysergide in cats deprived of paradoxical sleep.

Methysergide maleate, a 5-hydroxytryptamine receptor blocker, was administered to cats deprived of paradoxical sleep for 48 hours. During the first six hours after methysergide, the latency to the first slow-wave sleep and paradoxical sleep episodes was increased and total sleep time decreased. The decrease in sleep reflects a loss of paradoxical sleep, while the amount of slow-wave sleep remained unchanged. Slow-wave sleep time, though unchanged in amount, was displaced to the end of the six-hour recording period. These results suggest that paradoxical sleep in cats is more sensitive to methysergide action than is slow-wave sleep.

Animals↗
PubMed1975

The selective effects of alpha-methyl aromatic amino acids on brain monoamine metabolites and behavior in cats.

Alpha-methyldopa or alpha-methylmetatyrosine (100 mg/kg) were administered orally to cats and the EEG recorded for 9 hours. Through the first 6 hours after each administration, the concentration of cisternal cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) selectively decreased from control (hour 0) while homovanillic acid (HVA) levels showed only small changes. On observation, the animals were quiet but awake. At 9 hours after alpha-methyldopa administration, the percentage decrease of 5-HIAA was significantly greater from the percentage decrease of HVA. The EEG record from 6-9 hours following either drug showed fewer intervals of EEG synchronization in both duration and frequency. These results indicate that behavior and EEG can be related to changes in brain monoamine metabolism determined in CSF. After either drug administration, dopamine turnover (as indicated by HVA) was higher than that of serotonin (as indicated by 5-HIAA) which corresponded to EEG desynchronization and other behavioral indicators of wakefulness.

Amino Acids↗
PubMedDate not supplied

Sleep apnea in normal and REM sleep-deprived normotensive Wistar-Kyoto and spontaneously hypertensive (SHR) rats.

The effects of hypertension and REM sleep deprivation on spontaneous and postsigh apneas have been studied in normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive (SHR) rats by simultaneously monitoring their respiration and sleep by the EEG. The amount of REM and non-REM sleep in SHR rats was identical to WKY rats under control as well as REM sleep-deprived recording conditions. Hypertension was associated with an increase in postsigh apneas, as was evident by the increased postsigh apnea index in non-REM and total sleep in SHR rats when compared to normotensive WKY rats. In contrast, REM sleep deprivation suppressed the postsigh apnea expression both in non-REM and total sleep in SHR rats. The incidence of spontaneous apneas was increased by a combination of hypertension and REM sleep deprivation, as was shown in REM-deprived SHR rats, while each of these conditions alone had no effect on spontaneous apneas. These results suggest a role for hypertension in the postsigh apnea genesis and the existence of partially distinct mechanisms for the two types of apneas.

Animals↗
PubMedDate not supplied

Muramyl dipeptide does not induce slow-wave sleep or fever in rats.

The synthetic muramyl dipeptide, N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), is reported to increase slow-wave sleep and body temperature in cats, rabbits, and squirrel monkeys. The present study examined the ability of MDP to induce sleep and fever in rats. MDP was administered IP at 50, 250 and 500 micrograms/kg. Sleep and body temperature were monitored for 12 hr. MDP failed to affect the duration of wakefulness, S1, S2, or total (S1 + S2) slow-wave sleep. There was also no change in the latency to the first episode of S2 sleep. In contrast, rapid-eye-movement (REM) sleep was significantly suppressed for the first 6 hr after 250 and 500 microgram/kg doses of MDP. There was, however, a rebound increase in REM sleep after the initial period of suppression which resulted in no overall change in the amount of REM sleep. Body temperature was unaffected by MDP. Thus, we conclude that MDP has neither sleep-promoting nor pyrogenic actions in the rat when administered systemically at doses reported to be effective in several other species.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMedDate not supplied

Effects of carbachol and nicotine injected into the cerebral ventricles on electromyogram of conscious cats.

Carbachol and nicotine injected into the cerebral ventricles produced high amplitude and fast frequency activity in the electromyogram of conscious cats. Carbachol, much more than nicotine, caused bursts of such activity spaced at irregular time intervals accompanied by marked activity in the electrooculogram. In addition carbachol, but not nicotine, caused adynamia. The effect of nicotine laster 3-5 hr, while the effect of carbachol lasted up to 6 hr. The obtained results suggest that central muscarinic and nicotinic mediations are involved in the activation of the motor efferent system.

Animals↗
PubMedDate not supplied

Effects of ethanol injection to the preoptic area on sleep and temperature in rats.

Bilateral microinjection of ethanol to the preoptic area of rats causes a dose-dependent hypnotic effect at doses that do not affect brain temperature. Rats were polygraphically recorded for 6 h, and brain temperature was recorded every 10 min for 3 h. Administration of 0.047 mumol ethanol increased total sleep during the 3-6 h interval, while 0.24 and 0.47 mumol ethanol increased deep slow-wave sleep (SWS2) and total sleep during the 3-6- and 0-6-h intervals. The 0.24-mumol ethanol microinjections also increased REM sleep for the 0-6-h interval. No changes in sleep latencies were observed.

Animals↗
PubMedDate not supplied

R-zacopride, a 5-HT3 antagonist/5-HT4 agonist, reduces sleep apneas in rats.

The effects of R-zacopride, a benzamide with potent 5-HT3 receptor antagonist and 5-HT4 receptor agonist properties, on spontaneous apneas were studied in 10 Sprague-Dawley rats by monitoring respiration and sleep for 6 h. R-zacopride (0.5, 1.0 and 10.0 mg/kg) suppressed spontaneous central apneas during non-rapid-eye-movement (NREM) sleep by 50% (P=.05 for 0.5 mg/kg, P=.02 for 1.0 mg/kg and P=.001 for 10.0 mg/kg dose vs. control), and during rapid-eye-movement (REM) sleep by 80% by all doses tested (P<.0007) for at least 2 h after intraperitoneal injection. We conclude that R-zacopride, over a 20-fold dose range, significantly reduces central apnea expression during NREM and REM sleep in the rat. The efficacy of this compound to suppress central apneas most probably arises from its antagonist actions at 5-HT3 receptors or from its mixed agonist/antagonist profile at 5-HT4/5-HT3 receptors.

Animals↗
PubMedDate not supplied

Role of adenosine in sleep in rats.

The effects on sleep of N6-L-(phenylisopropyl) adenosine, cyclohexyladenosine and adenosine-5'-ethylcarboxamide were studied in rats. Also, the effects on sleep of deoxycoformycin, a potent inhibitor of adenosine deaminase, and adenosine were examined. In addition, we determined the effects of 48 h of REM sleep deprivation on adenosine (A1) receptors in specific brain structures. N6-L-(phenylisopropyl) adenosine and cyclohexyl-adenosine increased deep slow wave sleep and REM sleep whereas adenosine-5'-ethylcarboxamide increased only deep slow-wave sleep. At the dose of 0.9 mumol/kg all three adenosine analogs suppressed REM sleep and except for adenosine-5-ethylcarboxamide, were without an effect on deep slow-wave sleep. In accordance, administration of deoxycoformycin increased REM and deep slow-wave sleep. Intracerebroventricular administration of 1, 10 and 100 nmoles of adenosine to rats decreased waking, increased deep slow-wave sleep and increased total sleep. In addition, REM sleep deprivation significantly increased the number of A1 receptors (Bmax) in cerebral cortex and corpus striatum which correlates with the increased pressure for REM sleep and the onset of REM sleep rebound. When these data are taken together, they indicate a role for adenosine in the regulation of sleep and, in contrast to barbiturate and benzodiazepine hypnotics, increase in behaviorally deep and REM sleep.

Adenosine↗