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Biomedical subjects

D J McGinty

Publications and source records attributed to D J McGinty.

At least 19 recordsLinked to original sources
PubMed1999

Prenatal stress is associated with depression-related electroencephalographic sleep changes in adult male rats: a preliminary report.

1. Prenatal stress in rats has been shown to produce long-term behavioral, neuroendocrine and neurochemical changes. These changes may model aspects of human depressive illness. 2. In this pilot investigation, adult male offspring exposed to stress in utero and non-stressed controls were studied using 24-hour electroencephalographic sleep recordings. 3. Prenatally stressed animals demonstrated reduced latency to the onset of rapid eye movement (REM) sleep, prolongation of the first REM episode, and diminished slow-wave sleep. 4. Although preliminary, the observed changes parallel those seen in studies of human depression. These data further support the face validity of the prenatal stress model as a potential tool for future studies on the pathophysiology of depressive disorder.

Animals↗
PubMed1993

Selective increases in non-rapid eye movement sleep following whole body heating in rats.

Afternoon body heating has been reported to increase amounts of slow wave sleep (SWS) during the subsequent night in humans. This delayed effect of body heating on SWS has not been previously studied in laboratory animals. We examined the effect of whole body heating during the last 4 h of the light period on sleep and brain temperature (Tbr) during the subsequent twelve hour period in rats. Whole body heating was accomplished by elevating ambient temperature, typically to 33-35 degrees C, which increased Tbr to 40 +/- 0.5 degrees C. This condition was compared to a sleep-matched control condition, a sleep-deprived control condition and to a baseline condition. Following heating, non-rapid eye movement sleep 2 (NREMS2 or deep NREMS) was significantly increased during the first 2 h of the recovery period compared with baseline and sleep-matched control conditions and during the first hour compared with the totally sleep-deprived condition. NREMS1 was not significantly changed by heating. Rapid eye movement sleep was not different following heating compared to the sleep-matched and sleep-deprived control conditions but was significantly increased during the first hour of the recovery period following heating compared to baseline. Tbr was significantly lower for the first 5 h and the 7th h following heating compared to all three other conditions. Possible relationships between the regulation of sleep and temperature are discussed.

Animals↗
PubMed1986

Pontine neuronal response to local cholinergic infusion: relation to REM sleep.

In behaving cats, a cholinergic agonist, carbachol, or Ringer's solution were infused into the pontine reticular formation (PRF). Extracellular microelectrode recordings were obtained from single neurons located 1-4 mm from the infusion site. Sleep polygraphic variables were also recorded. Carbachol microinfusions into the PRF area between the locus coeruleus and the genu of the seventh nerve readily triggered some or all of the tonic and phasic components of REM sleep. The resulting REM-like states had a mean duration of 30 min. In 56 reticular units studied during carbachol infusions, compared to Ringer's, we observed the following significant responses: 26.6% (16 cells) increased discharge rate, 55.4% (31 cells) decreased discharge rate, 12.5% (7 cells) showed no change, while 3.5% (2 cells) showed a biphasic response. Both incremental and decremental neuronal responses evoked by carbachol preceded or coincided with the onset of REM-like sleep periods, and persisted throughout these periods. The subpopulation of cholinoceptive PRF neurons accelerated during both spontaneous and carbachol-induced REM sleep is most likely to account for REM sleep triggering by carbachol. The PRF neurons found to be decelerated by carbachol displayed under control conditions, the accelerated discharge pattern during REM sleep which is typical of PRF neurons. Since either discharge acceleration or deceleration may occur during REM-like states the discharge pattern of this subpopulation of PRF neurons may not be critical for REM sleep generation.

Animals↗
PubMed1986

Alterations in blood pressure and REM sleep after pontine carbachol microinfusion.

Infusions of cholinomimetics, either systemically in normal humans, or directly into the brain stem of unanesthetized cats and rats, readily induce rapid eye-movement (REM) sleep. In anesthetized cats and rats, infusions of cholinomimetics have been shown to produce both increases and decreases in arterial blood pressure. We determined the relation of these blood pressure changes to REM sleep, by examining both blood pressure and sleep states after injecting carbachol at midbrain, pontine, and medullary sites in unanesthetized cats. In the pons, carbachol infusions produced an early decrease in blood pressure followed by a sustained hypertensive effect. The early blood pressure decrease was associated with the occurrence of REM sleep; however, higher values were associated with later REM sleep episodes. In other brain stem sites carbachol did not produce REM sleep or its associated reductions in blood pressure. Instead it produced a hypertensive response that increased throughout the 1-h observation period. We hypothesize that pontine muscarinic mechanisms trigger REM sleep and a REM sleep-associated decrease in blood pressure. Thereafter, nicotinic receptors mediating the blood pressure increase override the muscarinic-induced decrease.

Animals↗
PubMed1984

Sleep apnea in cluster headache.

The impetus to study sleep changes in a cluster population arose from a recent hypothesis that predicted the finding of sleep apnea in this disorder. It holds that cluster attacks may occur in response to oxygen desaturation. Proposed mechanisms involve impairment of carotid body activity secondary to hypothalamic-vasomotor regulatory dysfunction. Five chronic and five episodic cluster patients underwent nocturnal polysomnography, utilizing standard equipment for monitoring sleep status, cardiac activity, nasal and buccal air flow change, chest and abdominal breathing, muscle activity and oxygen saturation. All episodic patients and one of five chronic patients were found to have sleep apnea (60%). Mean apneas per hour during NREM sleep were similar to that of REM sleep; 26.7 and 28.2, respectively. Six patients with sleep apnea experienced 14 cluster headache attacks during the study period. Eight attacks (57%) followed episodes of oxygen desaturation ranging from 65% to 85%. In the sleep apnea group, 8 out of 14 attacks (57%) were associated with REM; three without, and five following oxygen desaturation. Of the non-apnea group, all of whom had chronic cluster headache, none of 5 attacks were associated with oxygen desaturation, and only 2/5 attacks occurred in relation to REM. Thus, our study showed that sleep apnea was a common finding in a randomly selected group of episodic cluster patients; and most nocturnal attacks were preceded by oxyhemoglobin desaturation and REM-related. These findings were uncommon in the chronic cluster group.

Adult↗
PubMed1982

Sleep and medial reticular unit responses to protein synthesis inhibitors: effects of chloramphenicol and thiamphenicol.

This study utilized a newly developed combination push-pull cannula/microdrive-microwire device to record single-unit activity within the diffusion field of substances introduced into the brainstem. Single unit activity within the midbrain and pontine medial reticular formation (RF) and sleep were recorded following either perfusion or oral administration of protein synthesis inhibitors, chloramphenicol and thiamphenicol. Chloramphenicol administration led to significant reductions in the frequency, but not the duration, of individual REM episodes without altering slow-wave sleep. During control experiments in slow-wave sleep, incipient REM was characterized by substantial increases in medial RF unit activity which occurred in association with the appearance of PGO spikes. On the other hand, discharge rates of medial RF neurons were markedly attenuated by chloramphenicol but were not consistently affected by thiamphenicol. These findings suggest that reduced unit activity contributes to the REM-suppressive effects of protein synthesis inhibitors.

Animals↗
PubMed1982

Developmental comparison of sleep EEG power spectral patterns in infants at low and high risk for sudden death.

Power spectral density measured from central cortical EEG recordings during sleep was compared in two groups of 20 infants each at intervals between 1 week and 6 months of age. One group consisted of siblings of infants who had previously died of the sudden infant death syndrome, as determined by history and autopsy report (sibling group). The second group was made up of age, sex, and socioeconomically matched infants with no familial history of sudden infant death (control group).

Age Factors↗
PubMed1981

Respiratory patterns associated with hemoglobin desaturation during sleep in chronic obstructive pulmonary disease.

Respiration during sleep was monitored in ten patients with chronic obstructive pulmonary disease (COPD) and related to measures of hemoglobin saturation and intrathoracic pressure (ITP) or abdominal wall movement. Seven of the ten patients showed episodic hemoglobin desaturation of at least 5 percent during sleep. Two distinct patient groups could be distinguished on the basis of ITP measurements and breathing patterns. Desaturation was associated with reduced negative ITP or respiratory movement in three patients and with increased negative ITP or respiratory movement in four patients. These data suggest that desaturation may result from at least two distinct mechanisms, involving reduced respiratory effort in one group and increased upper airway occlusion in the other. Desaturation associated with reduced respiratory effort was primarily REM-sleep related and consisted of a few sustained episodes. Desaturation episodes associated with upper airway occlusion occurred in all stages of sleep and were very frequent and of short duration.

Airway Obstruction↗
PubMed1980

Determinants of oxygen desaturation in the course of ventilation during sleep in chronic obstructive pulmonary disease.

During sleep, none of 9 subjects with chronic obstructive pulmonary disease (COPD) were apneic. Despite ventilation, acute arterial oxygen desaturation of 11% or more occurred in 6 of them. The other 3 were nondesaturators (i.e., 3% or less desaturation) during sleep. The desaturation that occurred in the 6 subjects with COPD was associated with episodes of (1) esophageal pressure or abdominal respiratory movement that acutely decreased in amplitude during rapid-eye-movement (REM) sleep, or (2) esophageal pressure or abdominal respiratory movement that acutely increased in amplitude in association with snoring during non-REM and REM sleep. During daytime wakefulness, ventilatory responses to hypoxia and hypercapnia were markedly less in the 6 desaturators compared with the 3 nondesaturators and 5 healthy control subjects. The decreased ventilatory responses in the 6 desaturators appeared to result from both impaired respiratory mechanical effectiveness and impaired respiratory center responsiveness to chemoreceptor stimulation. We suggest that subjects with COPD with these respiratory impairments are predisposed to develop severe nonapneic oxygen desaturation during the added respiratory impairment of REM sleep or of what appears to be sleep-related partial upper airway obstruction.

Chronic Disease↗
PubMed1979

Activity of medullary reticular formation neurons in the unrestrained cat during waking and sleep.

Single units, recorded in the medial medullary reticular formation (RF) in unrestrained, behaving cats, discharged in conjunction with specific movements and postures. Most cells were also active during REM sleep. Discharge rates in active waking and REM sleep were positively correlated and discharge patterns in these states were similar. We conclude that activity in these cells is related to the motor activation occurring in both active waking and REM sleep. We found no cells whose discharge was related in a non-specific way to motor tone or to REM sleep atonia. We discuss mechanisms by which medullary units with specific motor relations may give rise when stimulated to the relatively non-specific motor effects previously reported.

Animals↗
PubMed1979

Sleep-waking patterns in hypoxic kittens.

Kittens at 10, 20, and 40 days of age were made intermittently hypoxic in 10 or 7% oxygen chambers for either 3 or 8 days. Respiration, EKG, EEG, and neck and eye movements were recorded during hypoxia. Compared to 21% oxygen controls, hypoxic kittens had fewer and shorter epochs of active sleep, and longer epochs of quiet sleep. Some hypoxic kittens exhibited slow and labored respiration during quiet sleep and transitional epochs, which reversed during active sleep. Kittens that showed most pronounced respiratory changes or died had less active sleep than kittens that compensated adequately and survived. These results suggest that active sleep may be important for stimulation of respiration during infancy. Suppression of active sleep, augmentation of quiet sleep, or other disturbances to normal sleep-waking patterns during hypoxia, may increase the risk for hypoxic respiratory depression and death.

Animals↗
PubMed1979

Sleep apnea in hypoxic and normal kittens.

Frequency and characteristics of apneas were studied in 10-, 20-, and 40-day old kittens during several days of exposure to 21%, 10%, or 7% oxygen atmospheres. Ninety-seven percent of all apneas occurred during sleep or at transitions between sleep and waking states. Hypoxic kittens, compared to controls, had greatly decreased apnea frequency, but other characteristics of apneas did not differ significantly. Apneas in both control and hypoxic kittens were normal, stereotyped events and were not considered to represent pathological processes. Evaluation of events preceding apneas indicated that a majority of apneas followed augmented breaths and/or brief arousals. We suggest that apnea, heart rate changes during apnea, and frequently concurrent transitions in sleep-waking state may be causally related to these pre-apnea events. The results of this study and a parallel study of human infants suggest that below-normal apnea frequency may indicate hypoxemia and may be associated with higher risk for Sudden Infant Death Syndrome.

Age Factors↗