Search PubMed⌕ Search

Biomedical subjects

M Cabanac

Publications and source records attributed to M Cabanac.

At least 55 records · Page 3Linked to original sources
PubMed1994

Experimental study of the internal signal of alliesthesia induced by sweet molecules in rats.

To identify the preabsorptive signal that arouses alliesthesia, we compared the effects of five sweet molecules: glucose (3 g.5 ml-1), cyclamate (0.280 g.5 ml-1), saccharin (0.016 g.5 ml-1), aspartame (0.020 g.5 ml-1), and mannitol (3 g.5 ml-1) on the intestive aversive responses of rats. In Experiment 1, the sweet stimuli were adjusted to taste similarly sweet, and they were administered orally; they aroused similar ingestive responses. In Experiment 2, an isovolumetric load of each of the five molecules was administered in the stomach and its influence on ingestive/aversive response aroused by oral sucrose was recorded. Negative alliesthesia was obtained after gastric loads of glucose and mannitol, but not after gastric loads of cyclamate, saccharin, and aspartame.

Administration, Oral↗
PubMed1994

Cholecystokinin loses its satiating property in food deprived rats.

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with oral catheters. A gustatory stimulus of 50 microliters of 1.75 mol.l-1 sucrose was injected into the mouth every 5 min during 65 min. Five minutes after the beginning of the session, 2 micrograms.kg-1 cholecystokinin (CCK) were injected IP Typical ingestive facial consummatory responses were observed in response to sweet stimuli before IP CCK. Aversive consummatory responses were observed in response to sweet stimuli after the IP CCK (negative alliesthesia). In the second part of the experiment the rats were denied access to food for 36 h and their mean body weight decreased from 426 g to 395 g. When the food deprived rats were subjected again to the same gustatory sessions, the IP CCK was not followed by negative alliesthesia in response to sweet stimuli. After recovery of initial body weights CCK was followed again by a strong negative alliesthesia. These results in rats show that the CCK mediation of duodenal satiety was hindered by body weight decrease.

Animals↗
PubMed1994

Postingestive alliesthesia produced by exogenous cholecystokinin and blocked by abdominal vagotomy.

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with oral catheters. A gustatory stimulus of 50 microliters of 1.75 M sucrose was injected into the mouth every 5 min during 65 min. At 5 min, 2 micrograms/kg exogenous cholecystokinin (CCK) was injected intraperitoneally. Typical ingestive facial consummatory responses were observed in response to sweet stimuli before the load. Aversive consummatory responses were observed in response to sweet stimuli after the intraperitoneal exogenous CCK (negative alliesthesia). Control intraperitoneal injection of saline was not followed by negative alliesthesia in response to sweet oral stimuli. In the last part of the experiment rats were vagotomized or underwent sham operation. When the vagotomized rats were again subjected to the same gustatory sessions, the intraperitoneal exogenous CCK was not followed by negative alliesthesia in response to sweet stimuli, whereas sham-operated rats presented a strong negative alliesthesia. These results in rats suggest that CCK mediates duodenal preabsorptive signal for alimentary alliesthesia. They also suggest that the effect is peripheral, with the vagus nerve as afferent pathway.

Animals↗
PubMed1993

Selective brain cooling in humans: "fancy" or fact?

A mechanism that selectively cools the brain during hyperthermia is a well-accepted fact in animals. Selective brain cooling (SBC) during hyperthermia has also been proposed in humans, but this suggestion has met with considerable debate. Several authors have rejected the idea of human SBC for the following reasons: 1) SBC is illogical because this mechanism removes the error signal activating the defense against hyperthermia; 2) unlike other animals, humans do not pant and thus do not possess a powerful heat sink at a short distance from the brain; 3) humans do not have a carotid rete, the countercurrent heat exchanger between the arterial and venous bloods flowing in and out of the brain; 4) the high and constant arterial blood flow of the brain is sufficient to cool the brain under all conditions; and 5) the relatively low tympanic temperature (Tty) recorded in hyperthermic humans is not a sign of SBC, but rather is the sign of contamination of Tty by a low head skin temperature. These arguments are reviewed and rejected and results of several recent experiments are summarized. Finally, recent experimental articles that contradict the existence of human SBC or the validity of Tty are discussed and their conclusions refuted. This review points to overwhelming evidence in favor of human SBC.

Body Temperature Regulation↗
PubMed1993

Vasomotor response of the human face: laser-Doppler measurements during mild hypo- and hyperthermia.

The skin of the face is reputed not to vasoconstrict in response to cold stress because the face skin temperature remains steady during hypothermia. The purpose of the present work was to measure the vasomotor response of the human face to whole-body hypothermia, and to compare it with hyperthermia. Six male subjects were immersed in cold and in warm water to obtain the two conditions. Skin blood flow, evaporation, and skin temperature (Tsk) were recorded in three loci of the face, the forehead, the infra orbital area, and the cheek. Tympanic (Tty) and oesophageal (Toes) temperatures were also recorded during the different thermal states. Normothermic measurements served as control. Blood flow was recorded with a laser-Doppler flowmeter, evaporation measured with an evaporimeter. Face Tsk remained stable between normo-, hypo-, and hyperthermia. Facial blood flow, however, did not follow the same pattern. The facial blood flow remained at minimal vasoconstricted level when the subjects' condition was changed from normo- to hypothermia. When the condition changed from hypo- to hyperthermia a 3 to 9-fold increase in the blood flow was recorded. From these results it was concluded that a vasoconstriction seems to be the general vasomotor state in the face during normothermia.

Adult↗
PubMed1993

Selective brain cooling is affected by wearing headgear during exercise.

The purpose of this work is to relate the concept of selective brain cooling (SBC) during exercise to heat loss from the head while either bare or covered. During hyperthermia, SBC is considered to occur if tympanic temperature (Tty) is lower than esophageal temperature (Tes). In experiment I the head heat loss was measured with and without headgear. Each of four subjects took part in three sessions of exercise on a cycle ergometer. The face was cooled to simulate outdoor conditions. The first session (no headgear) served as control for the two following sessions in which a headband and a woolen cap were worn. Evaporative and radiative-convective heat loss were monitored from the head. Wearing a cap significantly reduced the heat loss from the head compared with the control condition. During the headband session the heat loss was not significantly lower than the control values. Tty, Tes, and head skin temperatures (T(sk)) were also recorded. Tty was significantly lower (-0.55 +/- 0.15 degrees C) than Tes at the end of exercise (150-W exercise load) when no headgear was worn. During headgear sessions, Tty was no longer significantly lower than Tes, either during the headband (-0.15 +/- 0.31 degrees C) or during the cap session (-0.30 +/- 0.13 degrees C). In experiment II the influence of wearing headgear on temperature regulation was studied. Hand skin blood flow, hand T(sk), and heat loss from the hand were recorded in addition to the variables monitored in experiment I. Wearing headgear elevated Tty and peripheral vasomotor responses, whereas Tes evolved in the opposite direction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Pleasure: the common currency.

At present as physiologists studying various homeostatic behaviors, such as thermoregulatory behavior and food and fluid intake, we have no common currency that allows us to equate the strength of the motivational drive that accompanies each regulatory need, in terms of how an animal or a person will choose to satisfy his needs when there is a conflict between two or more of them. Yet the behaving organism must rank his priorities and needs a common currency to achieve the ranking (McFarland & Sibly, 1975, Phil. Trans. R. Soc. Lond. 270 Biol 265-293). A theory is proposed here according to which pleasure is this common currency. The perception of pleasure, as measured operationally and quantitatively by choice behavior (in the case of animals), or by the rating of the intensity of pleasure or displeasure (in the case of humans) can serve as such a common currency. The tradeoffs between various motivations would thus be accomplished by simple maximization of pleasure. In what follows, the scientific work arising recently on this subject, with be reviewed briefly and our recent experimental findings will be presented. This will serve as the support for the theoretical position formulated in this essay.

Animals↗
PubMed1992

Ingestive/aversive response of rats to sweet stimuli. Influence of glucose, oil, and casein hydrolyzate gastric loads.

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with gastric and oral catheters. A gustatory stimulus of 50 microliters of 0.6 mol.l-1 sucrose was injected into the mouth every 5 min during 90 min. At time zero, one of seven loads was injected into the stomach. These consisted of, 5 ml of water, or 5 ml solution containing 1 g glucose, 3 g glucose, 1 g casein hydrolyzate, 3 g casein hydrolyzate, or of oil 0.6 ml, or 1.4 ml. The typical ingestive facial consummatory responses in response to sweet stimuli were observed prior to all gastric loads, and also after the water load. On the other hand, the consummatory responses to sweet stimuli turned aversive after all three high-calorie gastric loads. The magnitude of this decrease in palatability (negative alliesthesia) was similar after glucose, casein hydrolyzate, and oil. The reversal of the consummatory responses from ingestive to aversive did not reach the threshold of statistical significance after the three low-calorie gastric loads. These results would tend to show that the intestinal signal for alimentary alliesthesia is nonspecific.

Animals↗
PubMed1992

Acute, but not chronic, exercise lowers the body weight set-point in male rats.

The influence of muscular training on overall energy balance and body weight is not clear. A group of male rats was trained to feed every day from 1000 to 1200. Then the intersect of regression line of food hoarded during meal time vs. body weight with the X-axis was measured. Finally, the rats were trained to run 1 h every day on a motor-driven treadmill. When the training took place in the morning, just before the hoarding session, the mean intersect was significantly lowered from control (497 +/- 18 g to 433 +/- 9 g). When the training took place in the afternoon, after the hoarding session, the mean intersect was not significantly different (504 +/- 21 g) from control. Food intake during the hoarding sessions was affected neither by body weight changes nor by muscular exercise. These results suggest that the set-point for body weight regulation is acutely lowered just after muscular exercise, but is not influenced by chronic training.

Animals↗
PubMed1992

Duodenal preabsorptive origin of gustatory alliesthesia in rats.

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with gastric, duodenal, and oral catheters. A gustatory stimulus of 50 microliters of 1.75 mol/l sucrose was injected into the mouth every 5 min for 65 min. At time 0, 0.5 ml containing 0.3 g glucose was injected into the stomach or into the duodenum. Typical ingestive facial consummatory responses were observed in response to sweet stimuli prior to the load. Aversive consummatory responses were observed in response to sweet stimuli after the glucose duodenal load (negative alliesthesia). The gastric load of glucose was not followed by negative alliesthesia in response to sweet oral stimuli. In the last part of the experiment the rats were vagotomized. When the rats were subjected again to the same gustatory sessions, the duodenal load was followed by weak and delayed negative alliesthesia in response to sweet stimuli. These results in rats parallel results obtained in human subjects and reinforce the hypothesis of the existence of a duodenal preabsorptive signal for alimentary alliesthesia. They also suggest that the vagus nerve plays a part in the perception of satiety.

Absorption↗
PubMed1991

Stress hyperthermia: physiological arguments that it is a fever.

The theory that stress (or emotional) rise in central temperature (Tc) in rats is a fever with an upward shift of the set-point temperature was tested with three experiments: 1) Measurement of tail skin temperature and Tc during the emotional Tc rise; 2) Investigation of the effect of ambient temperature on the emotional Tc rise; and 3) The assessment of emotional Tc rise during daytime and nighttime. Skin vasomotor responses helped the increase of Tc toward a higher level and contributed to the regulation of central temperature at this new higher level. The cold environment did not diminish the emotional rise of central temperature as it would be expected in the case of a hyperthermia. However, at night emotional fever reached a higher level than during the daytime, suggesting that prostaglandin rise in Tc is distinct from emotional or stress-induced hyperthermia. In conclusion, the experiments reported here confirm the hypothesis that the rise of Tc induced by handling or disturbance of the rats is regulated, and is due to a shift of the set-point as occurs in fever.

Animals↗
PubMed1991

Facial consummatory responses in rats support the ponderostat hypothesis.

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with gastric and oral catheters. A gustatory stimulus of 50 microliters of 1.75 mol.1-1 sucrose was injected into the mouth every 5 min during 60 min. At time zero, 1.7 ml of 3.3 mol.1-1 glucose was injected into the stomach. Typical ingestive facial consummatory responses were observed in response to sweet stimuli prior to the gastric load. Aversive consummatory responses were observed in response to sweet stimuli after the glucose gastric load (negative alliesthesia). The rats were then fasted until they had lost about 14% of their body weight (from 411 +/- 34 g to 353 +/- 28 g). When lean, the rats were subjected to the same gustatory session as in the control period described above. In lean rats the gastric load of glucose was not followed by negative alliesthesia in response to sweet oral stimuli. In the last part of the experiment the rats were fed ad lib and they recovered their initial body weight. When the rats were subjected again to the same gustatory sessions, the gastric load was followed by negative alliesthesia in response to sweet stimuli. Thus, after recovering their initial body weight, the rats displayed the same response as in the control sessions prior to losing weight. These results in rats parallel results obtained in human subjects, and reinforce the hypothesis of the existence of a ponderostat regulating body mass.

Animals↗
PubMed1991

Heat loss from the human head during exercise.

Evaporative and convective heat loss from head skin and expired air were measured in four male subjects at rest and during incremental exercise at 5, 15, and 25 degrees C ambient temperature (Ta) to verify whether the head can function as a heat sink for selective brain cooling. The heat losses were measured with an open-circuit method. At rest the heat loss from head skin and expired air decreased with increasing Ta from 69 +/- 5 and 37 +/- 18 (SE) W (5 degrees C) to 44 +/- 25 and 26 +/- 7 W (25 degrees C). At a work load of 150 W the heat loss tended to increase with increasing Ta: 119 +/- 21 (head skin) and 82 +/- 5 W (respiratory tract) at 5 degrees C Ta to 132 +/- 27 and 103 +/- 12 W at 25 degrees C Ta. Heat loss was always higher from the head surface than from the respiratory tract. The heat losses, separately and together (total), were highly correlated to the increasing esophageal temperature at 15 and 25 degrees C Ta. At 5 degrees C Ta on correlation occurred. The results showed that the heat loss from the head was larger than the heat brought to the brain by the arterial blood during hyperthermia, estimated to be 45 W per 1 degree C increase above normal temperature, plus the heat produced by the brain, estimated to be up to 20 W. The total heat to be lost is therefore approximately 65 W during a mild hyperthermia (+1 degrees C) if brain temperature is to remain constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Postingestive alliesthesia: the rat tells the same story.

Facial consummatory responses reflecting ingestive and aversive perceptions were studied and quantified in rats chronically implanted with gastric and oral catheters. A gustatory stimulus of 50 microliters of 0.6 mol.l-1 sucrose was injected into the mouth every 5 min during 60 min. At time zero, 5 ml of either 1.1 mol.l-1 glucose or water were injected into the stomach. The typical ingestive facial consummatory responses were observed in response to sweet stimuli prior to all gastric loads, and after the water loads. On the other hand, the aversive consummatory responses were observed in response to sweet stimuli after glucose gastric loads. The reversal of the consummatory responses from ingestive to aversive was stronger with higher concentration of the gastric load, and relatively independent from the volume of the load or the amount of glucose injected intragastrically. These results in rats parallel human postingestive alliesthesia.

Animals↗
PubMed1989

Rosacea: disturbed defense against brain overheating.

Tympanic (Tty), esophageal (Tes), forehead, and hand skin temperatures, as well as the forehead evaporation rate were recorded in six men (four suffering from rosacea and two healthy controls) before, during, and after 1 h of warm bath (38 degrees-39 degrees C). During the last 30 min of the bath, the subject's face was vigorously fanned (14 m/s). Blood flow was explored with ultrasonic Doppler in the emissary veins of the cranium during normothermia before entering the bath, and during hyperthermia just after leaving it. Under normothermic conditions, Tty was higher than Tes in all subjects. In three patients, no blood flow could be detected in the ophthalmic emissary veins whereas in the fourth patient as well as in both control subjects, blood flowed from the intracranium to the face. During hyperthermia, face fanning decreased Tty by 0.25 degrees +/- 0.05 degrees C (+/- SEM) below Tes in the control subjects whereas in all patients Tty remained warmer than Tes by 0.1 degrees C. Doppler recordings showed a rapid inward blood flow from the skin to the brain in the controls during hyperthermia. In patients, however, there was no change from normothermia in the blood flow patterns of vena angularis oculi. Their forehead temperature was permanently higher than in control subjects. Venous blood flow from the skin to the brain appears to be suppressed in rosacea, thus inhibiting selective brain cooling in hyperthermic conditions. The importance of this mechanism in the pathogenesis of rosacea and its significance as a means of investigation are discussed.

Adult↗