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R V Rial

Publications and source records attributed to R V Rial.

At least 19 recordsLinked to original sources
PubMed2006

Antioxidant response analysis in the brain after pilocarpine treatments.

Cholinergic and gabaergic systems play an important role generating electroencephalographic activity and regulating vigilance states. Pilocarpine is a cholinergic agonist commonly used to induce seizures and an epilepticus-like state in rodents. A relationship between status epilepticus and reactive oxygen species has been also suggested which could result in seizure-induced neurodegeneration. The aim of this study was to evaluate the existence of oxidative damage as well as the antioxidant enzyme response in cortex and hippocampus after the administration of an intraperitoneal (350 mg/kg) and an intracerebroventricular (360 microg, 1 microl) pilocarpine injection in rats. The GABA agonist muscimol (1 mg/kg, i.p.), with described neuroprotective properties, was used as a negative control. Only systemic pilocarpine induced oxidative damage. Malondialdehyde levels, as a marker of lipid peroxidation (LP), increased in both regions (55-56%). Catalase (52-80%) and superoxide dismutase (53-60%) activities also rose in both regions but glutathione peroxidase activity only increased in cortex (45%). Glutathione reductase and caspase-3 activity did not change. In conclusion, systemic pilocarpine produced oxidative brain damage, whereas local pilocarpine brain injection had no effects. Moreover, the enzymatic determinations performed in this study are a good tool to study brain injury in pharmacological manipulations such as the ones used in short recording EEG studies.

Animals↗
PubMed2000

Why we sleep: the evolutionary pathway to the mammalian sleep.

The cause of sleep is a complex question, which needs first, a clear distinction amongst the different meanings of a causal relationship in the study of a given behavior, second, the requisites to be met by a suggested cause, and third, a precise definition of sleep to distinguish behavioral from polygraphic sleep. This review aims at clarifying the meaning of the question and at showing the phylogenetic origin of the mammalian and avian sleep. The phylogenetic appearance of sleep can be approached through a study of the evolution of the vertebrate brain. This began as an undifferentiated dorsal nerve, which was followed by the development of an anterior simplified brain and ended with the formation of the multilayered mammalian neocortex or the avian neostriate. The successive stages in the differentiation of the vertebrate brain produced, at least, two different waking types. The oldest one is the diurnal activity, bound to the light phase of the circadian cycle. Poikilotherms control the waking from the whole brainstem, where their main sensorymotor areas lie. Mammals developed the thalamocortical lines, which displaced the waking up to the cortex after acquiring homeothermy and nocturnal lifestyle. In order to avoid competence between duplicate systems, the early waking type, controlled from the brainstem, was suppressed, and by necessity was turned into inactivity, probably slow wave sleep. On the other hand, the nocturnal rest of poikilotherms most probably resulted in rapid eye movement sleep. The complex structure of the mammalian sleep should thus be considered an evolutionary remnant; the true acquisition of mammals is the cortical waking and not the sleep.

Adaptation, Physiological↗
PubMed1997

Main trends in rectal temperature during sleep. Hypnogram and thermogram.

Changes in sleep state and night-time body temperature were studied in 13 healthy young men. Temperature data showed serial dependence that was removed when considering three main segments of the thermogram: an initial rapid drop between 60 and 140 min after lights off, followed by a slower decrease to the thermal minimum and a final temperature increase until waking. The first segment was fitted by a two-term function, while the other two segments were fitted by linear regression. Temperature data obtained after fitting these models were stationary and used to calculate the fast Fourier transformation and the cross-correlation functions between the hypnogram and the thermogram of each subject. Attaining stationarity has unmasked short oscillations during sleep and some temperature series showed the presence of ultradian oscillations with a period of 90-100 min. Significant cross-correlations between sleep stages and body temperature were found, and the parameters of the two-term function fitted to the first temperature drop were related to the sign of the correlation and to that time series (sleep or temperature) which preceded the other during the night.

Adult↗
PubMed1994

Reptilian waking EEG: slow waves, spindles and evoked potentials.

Signal spectral analysis procedures were used to compute the power spectrum of Gallotia galloti lizards EEG at different (5-35 degrees C) body temperatures. EEG power spectra were mainly characterized by a low frequency peak between 0.5 and 4 Hz which was present at the different body temperatures. A second spectral peak, corresponding to spindles of similar pattern to the sleep spindles of mammals, also appears in the spectra. The peak frequency of the spindles increased with the body temperature. Flash evoked potentials were characterized by a slow triphasic component upon which a spindle was superimposed, adopting a morphology similar to the K complexes of mammalian sleep. The characteristics of this EEG and evoked potentials support the hypothesis of homology between the waking state of the reptiles and the slow wave sleep of mammals.

Animals↗
PubMed1993

Temperature drop and sleep: testing the contribution of SWS in keeping cool.

Sleep and body temperature characteristics were studied in man in baseline (B), 24 h-constant routine (CR) and recovery (R) after the CR. The sleep advanced and deepened the trough of the minimum temperature when compared with CR. No relevant difference in minimum body temperature, or in the slope of temperature decrease was found, however, between B and R sleeping nights. No correlation was found between the amount of slow wave sleep and body cooling. The results do not support a homeostatic role of slow wave sleep in brain and/or body cooling.

Adult↗
PubMed1988

Developmental study of digestive motor response to dietary pattern in young broilers.

1. Gastrointestinal (GI) morphometry and motility were measured in young broilers (3, 8 and 15 days old) when they were submitted to three dietary patterns (ad libitum food, acute 48-hr fast and cumulative semi-starvation). 2. All GI regions were hypertrophied when acute or intermittent starvation were applied; lightly when acute starvation was applied and strongly with intermittent starvation. 3. All the 3-, 8- and 15-day-old acutely and intermittently starved chickens increased GI motility at the shortest times (0.5 and 1 hr) after the marker administration, but decreased GI motility at the longest times (2 and 4 hr). 4. The GI motor response of intermittently starved chicks was faster than the observed one in acutely starved chicks. The GI tract of intermittent starved chicks increased its motor response proportionally to the broilers age, while acutely starved chicks decreased their GI motility when the broilers age was increased. 5. A relationship between morphometrical and motor GI responses to dietary pattern has been inferred. From the gizzard and small bowel hypertrophy caused by intermittent starvation, an increased reflex GI motor response can be expected. Acute starvation only caused a light increase of GI motility, because it only increased the gizzard morphometry. 6. We concluded that young chicks respond to acute starvation by means of a short-term mechanism (an increase of GI motor reflexes) and responds to intermittent starvation by means of a medium- and long-term mechanism (a hypertrophy of GI tract and its subsequent increase of GI motor reflexes).

Age Factors↗
PubMed1987

Altered responsiveness to ambiental stimuli in altered thyroidal states.

Hypothyroidal rats produced by low iodine diet or propylthiouracyl (PTU) were less active in the open field and received fewer food reinforcements than controls in a lever press situation at both 22 degrees C and 1 degree C. The hypothyroid rats also pressed less when heat was the reinforcer. On the other hand, hyperthyroidal rats produced by thyroid powder ingestion showed reduced emotionality in the open field. Acute exposure to cold failed to increase their alimentary or heat reinforced behavior. The results suggest that hypothyroidism produces a general inattention to the environment. This is found whether the environmental stimulus is an opportunity to explore, access to food or the availability of external heat.

Animals↗
PubMed1987

Effect of thyroidal state on the gastrointestinal transit and emptying of young broilers.

1. In newly hatched broilers, propylthiouracil and thyroid powder added to the diet produced hypothyroidism and hyperthyroidism, respectively. After 4-5 days of treatment body and thyroid weight changed, but no differences in body temperature were found. 2. The hyperthyroidal animals had high mortality rate and the hypothyroidal ones showed significantly lower glycemia values. 3. The gastrointestinal transit and emptying of 8 and 15 days old hypo-, hyper- and euthyroidal broiler chicks were measured using 14C-PEG-4000 as a marker. 4. Hypothyroidism prolonged GI transit and emptying, whereas hyperthyroidism modified these parameters in a way dependent of the elapsed time after the test meal: at 0.5 and 1 hr transit and emptying were quick, but at 2 and 4 hr the transit was slow. 5. Hyperthyroidism also delayed the transit of large bowel intraluminal contents in 15-day-old chickens. 6. These results are very similar to those of starvation, suggesting an important interaction between diencephalon, thyroid gland and GI motility in young chickens.

Animals↗
PubMed1986

Ontogeny of the gastrointestinal motility in young broilers.

Gastrointestinal motility of young broilers (1, 8 and 15 days old) was measured by means of 14C-polyethylene glycol-4000. Two motor patterns can be observed: GI segments anterior to ileum increased their motility proportionally to the broiler age. GI segments below ileum decreased their motility when the broiler age is increased. It is concluded that these motor patterns are due to immaturity of gastric motility, early learning of food intake regulation and/or interference between prenatal and postnatal nutrition. Proventriculus and duodenal loop showed to be transit segments, with independence of the broiler age.

Age Factors↗
PubMed1986

[Effect of intracerebroventricular injection of histamine on the behavior of the white rat].

Previous references showed that the histamine injected peripherically produced a deterioration of the learning in experimental animals. The effects of 100 and 200 micrograms of histamine administered in the cerebral lateral ventricle, have been tested using an experimental paradigm which isolated attentional, motivational, and motor factor from the complex learned behavior. The obtained results showed to be similar to those produced by peripheric injection, and demonstrated a worsening in attentional, motivational, and motor parameters.

Animals↗
PubMed1978

Kindling effect in the reptilian brain: motor and electrographic manifestations.

The extension of the kindling effect to the reptilian brain is reported with two experimental groups of lizards Lacerta galloti. The first group received daily stimulation in the telencephalic cortex at a current level sufficient to produce motor responses. These motor responses occurred only when the stimulus was applied, and disappeared when it was terminated. However, the threshold for evoking these motor responses decreased in 20 days of stimulation, and the responses evolved to stimulus-bound convulsions. In the second group, the stimulus was too low to produce motor responses, but it developed afterdischarges and spontaneous recurrent electrographic seizures that increased their duration with each stimulation. Reptilia are discussed as useful experimental animals for studying the kindling phenomenon.

Animals↗
PubMed1978

[Temperature effects on the EEG and evoked potentials in Reptilia (Lacerta galloti) (author's transl)].

The effect of temperatures from 5 degrees to 40 degrees C on EEG amplitude, evoked potentials amplitudes to optical stimuli and latencies of components of evoked potential in lizard Lacerta galloti, have been studied, by means of chronically implanted electrodes in dorsal and medial telencephalic cortex. Evoked responses show with greater amplitude in the medial cortex, although latencies were closely similar for both regions.

Animals↗
PubMed1977

[Electrophysiology of the telencephalic cortex in reptiles (lacerta galloti); EEG and evoked potentials (author's transl)].

EEG recordings were made on the telencephalic cortex of the saurius Lacerta galloti by means of chronically and acute implanted electrodes. In acute experiment cases, the animal was curariced and given artificial respiration. In chronic experiment cases the recordings were made extradurally, epicortically and subcortically. Evoked potentials were obtained by optical, acoustic and somatosensory stimulations. The results show two main aspects: 1. High amplitude slow waves. 2. Very abundant spindles of high frequency. They also show clear responses to sensorial stimuli but without precise topographical localization.

Acoustic Stimulation↗
PubMedDate not supplied

[The evolution of sleep: birds at the crossroads between mammals and reptiles].

INTRODUCTION: The evolution of sleep is one of the mysteries surrounding the sleep. Since the discovery of the two phases in the mammalian sleep, NREM and REM, the sleep researchers have unsuccessfully tried to understand their origin and the causes of the sleep duality. Looking for an answer to these questions, the sleep of reptiles (the parental group of mammals) and birds (also descending from reptiles) has been studied. As a result, NREM and REM were found in birds but not in reptiles, and the question remains thus unresolved. DEVELOPMENT AND CONCLUSIONS: This review presents a critical analysis of the published sleep studies developed in birds and points to a possible cause of the conflict: considerable doubts can be cast on the existence of the two sleep phases in birds. If birds turn to have only one sleep phase, they would have a very similar sleep to that of reptiles. As a consequence, the two phases, REM and NREM, would be exclusive of mammals, and both would have appeared as a consequence of the evolutionary changes in the development of the brain from reptiles to mammals.

Animals↗