Biomedical subjects

R H Pastel

Publications and source records attributed to R H Pastel.

6 recordsLinked to original sources

PubMed1991

Effects of controllable vs. uncontrollable stress on circadian temperature rhythms.

The effects of sustained stress on body temperature were investigated in rats implanted with mini-transmitters that permitted remote measurement of body temperature. Temperature was first monitored during control conditions. Following the control period, rats were either shaped to avoid/escape signalled around-the-clock intermittent footshock (controllable stress) or yoked to the controlling rats such that the controlling rat and the yoked rat received shock of the same duration, but only the controlling rat could terminate shock by pulling a ceiling chain. Under control conditions, rats demonstrated regular rhythms in body temperature which averaged 1 degree higher during the 12-h dark cycle than the light cycle. Stress disrupted the rhythm and markedly decreased the night-day difference in temperature, especially in the yoked rats in which almost no difference between light and dark cycle temperature was seen. The disruption was most marked for the first days of stress. A regular temperature rhythm was reestablished following about 5 days of stress although the stress condition continued. Leverpressing for food was also affected by the stress conditions with both stress groups leverpressing less than controls and the uncontrollable stress group pressing less than the controllable stress group. These data offer additional evidence of the increased pathophysiological effects of uncontrollable as compared to controllable stress.

Animals↗

PubMed1989

Suppressant effects of selective 5-HT2 antagonists on rapid eye movement sleep in rats.

The effects of the novel, highly selective serotonin-2 (5-HT2) antagonists, ICI 169,369 and ICI 170,809, on 24 h EEG sleep-wake activity were studied in the rat. Both compounds caused a dose-related increase in the latency to rapid eye movement sleep (REMS) and significantly suppressed cumulative REMS time up to 12 h postinjection. In contrast, neither drug disrupted slow-wave sleep continuity in as much as the latency to non-REMS (NREMS) and cumulative NREMS time were unchanged. However, at the highest dose tested (20 mg/kg) ICI 170,809 did produce a significant increase in total NREMS time during the second half of the sleep-awake cycle. These results demonstrate effects of selective 5-HT2 antagonists on sleep in rats which appear to be specific for REMS behavior, suggesting that the priming influence of serotonin on REMS may involve 5-HT2 receptor subtypes. The relationship between the REMS suppressant actions of these compounds and their consideration as therapeutic agents in depression is discussed.

Animals↗

PubMed1988

A microcomputer-based sleep system: data acquisition and system calibration programs.

A data acquisition program is described for the Apple II series of microcomputers that allows for continuous, direct monitoring of electrographic elements from cortical, hippocampal and muscle leads from rats. The program detects cortical delta waves and sigma activity, hippocampal theta activity and electromyographic activity. The detected elements are counted and stored in memory at 15 second intervals (bins). Every three hours, the data are transferred to disks for permanent storage and off-line analysis.

Animals↗

PubMed1987

Short-term effects of fluoxetine and trifluoromethylphenylpiperazine on electroencephalographic sleep in the rat.

Fluoxetine and trifluoromethylphenylpiperazine (TFMPP) were studied for their short-term effects on electroencephalographic sleep in male rats. Following single injection, each drug produced a sizeable, dose-related suppression of rapid-eye-movement (REM) sleep that persisted for 4-5 h (fluoxetine, 0.625-5 mg/kg; TFMPP, 0.10-1.25 mg/kg). TFMPP also consistently increased non-REM (NREM) sleep during the second hour after drug injection, though this effect was not dose-related (it was seen at all doses tested). Fluoxetine produced small effects on NREM sleep that varied non-systematically with dose and time after drug injection. TFMPP, but not fluoxetine, also increased at all doses the number of delta waves per minute of NREM sleep in the second hour. A structural analog of TFMPP that is inactive at serotonin (5-HT) receptors [4-(m-trifluoromethylphenyl)piperadine; LY97117] was also tested, and found to be devoid of effects on NREM and REM sleep. Both fluoxetine (a 5-HT reuptake blocker) and TFMPP (a 5-HT agonist) enhance transmission across 5-HT synapses, though by different mechanisms. Because they have the common effect of suppressing REM sleep, and in a dose-related manner, the data support the notion that 5-HT neurons in the brain, when active, can suppress REM sleep.

Animals↗

PubMed1984

The effects of clonidine on EEG wavebands associated with sleep in the rat.

Clonidine was studied for its effects in rats on the occurrence of several EEG waves that characterize the sleep/waking cycle. Intraperitoneal administration of the drug (0.001-1.0 mg/kg) at the onset of the daily light period induced low frequency (4-7 Hz) rhythmical slow activity (RSA), and suppressed delta-wave occurrence. These effects were more prominent with increasing dose. Clonidine also had a biphasic effect on spindles: at low doses it suppressed, while at high doses it enhanced spindle occurrence. These effects could not be characterized as modifications in any of the classical sleep stages. A clearly non-classical state was induced by the clonidine in these studies. These results suggest that in rat, effects of clonidine cannot simply be interpreted as an alteration in one or more of the classically-defined sleep states.

Animals↗

PubMed1984

Long term stability of rat sleep quantified by microcomputer analysis.

An inexpensive microcomputer system is described for the direct recording of electrographic data from animals. Using this system, electrographic data can be recorded continuously on a polygraph and simultaneously quantitated by the computer, for days or weeks. Our system quantifies the amounts of delta waves, spindle bursts, hippocampal RSA activity and movement spikes for 15 sec epochs. These electrographic data are stored by the computer and subsequently can be used to score sleep stages. We find that the computer reliably counts waves; using these data, it can then score sleep stages off-line with about 90% accuracy. With this system, we find that the minutes/hour of both SWS and REM are remarkably stable from day to day. The absolute number of delta waves, spindle bursts, trains of RSA and movement counts/hour also remain stable from day to day. This type of system should find significant application in situations where quantitation of longterm effects of drugs, diets and other environmental inputs on sleep states or EEG wave bands are of interest.

Animals↗