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Biomedical subjects

R Dantzer

Publications and source records attributed to R Dantzer.

At least 217 records · Page 12Linked to original sources
PubMed1980

Conditioned taste aversion as an index of lead toxicity.

Rats treated with lead acetate following the consumption of a solution with a distinct taste exhibited an aversion to the initially consumed solution. Conditioned taste aversion was reliably induced with 10--20 mg/kg lead acetate. Repeated treatment with lead did not enhance this effect when measured either in forced or in free choice conditions. The utility of the taste aversion procedure for evaluation of toxic agents is discussed.

Animals↗
PubMed1979

[Involvement of endorphins in the emotional behavior of pigs].

Social isolation and exposure to a new environment induce hyperactivity, vocalizations and ACTH release in weaned Piglets acutely submitted to this stress. These reactions are increased by pretreatment with morphine (0.5 and 1 mg/kg) and decreased by naloxone (1 mg/kg), suggesting that endogenous opiates modulate emotional behaviour in Pigs.

Adrenocorticotropic Hormone↗
PubMed1979

[Effect of a tryptophan lead on the swine adrenal cortex reactivity and behavioral response to stress].

Behaviour and plasma corticosteroid levels were investigated in pigs preloaded with 50 to 200 mg/kg 1-tryptophan. The treatment did not influence reactions to frustation and had no effect on continuous avoidance responding. However the adrenal response to the stress of new environment concomitant with delivery of unavoidable shocks was decreased (fig. 1), as well as the behavioural response to a fear signal superimposed on a continuous avoidance paradigm (fig. 2). These results point out relatively specific psychotropic effects of a tryptophan load in pigs.

Adrenal Cortex Hormones↗
PubMed1979

[Behavioral alterations induced by post-natal exposure of the rat to lead].

The behaviour of rats exposed to various levels of lead acetate (0.5 ; 1 ; 2 and 4% in dam's diet) before weaning was recorded between 2 and 6 months of age. Higher locomotor and exploratory activities as well as better scores in active avoidance conditioning were observed in the 4% lead-treated rats. For lower doses, no behavioural alterations were recorded despite both detarded growth and increased mortality.

Animals↗
PubMed1978

Antipunishment effects of diazepam: interaction with shock and food deprivation levels in pigs.

The effects of 1mg/kg diazepam on punished behaviour of pigs were investigated under various degrees, of food deprivation and/or shock level. Responses emitted during the punishment signal were affected more by the shock level than by the degree of food deprivation while nonpunished response rates were modified by neither factor. Diazepam treatment increased the number of responses emitted during the punishment signal but interacted with the shock intensity: drug effects were attenuated when the shock intensity was severe, in spite of an equivalent control baseline. Diazepam also increased the overall rate of nonpunished responding. The drug treatment had no reliable effect on flinch and escape thresholds measured in separate experiments. The effects of diazepam on punished responding do not appear to be related to eventual changes in food motivation or sensitivity to electric shock.

Animals↗
PubMed1978

Increased resistance to satiation in diazepam-treated pigs.

Sated pigs, having a previous history of operant responding according to a CRF schedule, resumed responsing when put back in the Skinner box after 1 mg/kg diazepam. This effect did not appear to be related to the disinhibition of an extinction process.

Animals↗
PubMed1978

Behavioural and pituitary-adrenal characteristics of pigs differing by their susceptibility to the malignant hyperthermia syndrome induced by halothane anesthesia. 2. Pituitary-adrenal function.

Pituitary-adrenal function was investigated in two groups of Pietrain pigs differing by their susceptibility to the malignant hyperthermia syndrome induced by halothane, and in Large White pigs (LW). Plasma basal levels of glucocorticoids, measured by a protein binding technique, and plasma ACTH concentrations, determined by radioimmunoassay, did not differ according to halothane susceptibility but were higher in LW pigs compared with Pietrain pigs. The reactivity of the pituitary-adrenal axis to such stressors as exposition to a novel environment or shaking was the same for all experimental groups. The same was true concerning plasma levels of glucocorticoids and ACTH after injection of dexamethasone and response of the adrenal cortex to a standard dose of ACTH. These results demonstrate that LW pigs have a higher tonic secretion of ACTH than Pietrain pigs, but with identical phasic response to stimulations. Halothane susceptibility by itself appears to have no influence of pituitary-adrenal function.

Adrenal Cortex Hormones↗
PubMed1978

Behavioural and pituitary-adrenal characteristics of pigs differing by their susceptibility to the malignant hyperthermia syndrome induced by halothane anesthesia. 1. Behavioural measures.

Behavioural responses were compared in Pietrain pigs and in Large White pigs differing by their susceptibility to the malignant hyperthermia syndrome induced by halothane. Non reactive Pietran pigs (P--) displayed a higher level of locomotor activity in a new environment than either reactive Pietrain pigs (P+) or Large White pigs. Pietran pigs performed better in a latent learning proceudre (latency of approach or feeding response, after exploration of the new environment) and in a continuound P-- did not reach significance, but P+ pigs tended to be superior to P-- animals. The three groups did not differ on a measure of passive avoidance. These results suggest that Large White pigs are characterized by a lower ability to initiate active responding when confronted with aversive events. The same would be true when Pietrain positive pigs are compared with Pietrain negative pigs, although to a lesser extent.

Animals↗
PubMed1977

[Effects of diazepam on exploratory behavior of pigs (author's transl)].

The exploratory behavior of pigs was studied in two successive daily 20-mn sessions in a two-compartment box by counting the number of crossings from one compartment to the other and observing the activity patterns. Injection of 1 mg/kg diazepam before the first session increased the number of crossings without affecting the temporal decline of activity within the session; treated pigs did not attempt to escape the experimental situation and tended to be more perseverative in their activity patterns than control pigs. Injected before the second session, diazepam did not modify the exploratory behavior. There was no evidence of a state-dissociation effect in experimental groups for which the treatment condition differed from one session to the other. These results are discussed with respect to current theories about the behavioral effects of benzodiazepines.

Animals↗
PubMed1977

Effects of diazepam on behaviour suppressed by extinction in pigs.

Diazepam injected to pigs previously trained to perform an operant response for food according to a continuous reinforcement schedule significantly increased resistance to extinction compared to control pigs. In pigs submitted to a time-out procedure diazepam increased the number of nonreinforced responses at the beginning of the acquisition but was unable to disinhibit suppressed behaviour in the later stages of acquisition when the extinguished behaviour was well acquired. The results are discussed with respect to antiaversive or disinhibitory effects of benzodiazepines and an alternative interpretation, the strengthening of the prevailing behavioural tendency in the animal's repertoire at the time of test, is put forward.

Animals↗
PubMed1976

Fear-dependent variations in continuous avoidance behavior of pigs. I. Lack of effect of diazepam on performance of discriminative fear conditioning.

Pigs trained to avoid shocks by crossing a barrier in a shuttle-box according to a continuous avoidance procedure were submitted to a Pavlovian discriminative fear-conditioning procedure in which a tone was always followed by unavoidable shock (CS+) and another tone never followed by shock (CS-). The presentation of the CS+ on a test session in the shuttle-box induced an increase of the response rate while the CS- decreased the performance. Diazepam (1 mg/kg) administered before the test session did not modify the changes in avoidance response to each CS.

Animals↗
PubMed1976

Fear-dependent variations in continuous avoidance behavior of pigs. II. Effects of diazepam on acquisition and performance of Pavlovian fear conditioning and plasma corticosteroid levels.

Previously acquired continuous avoidance performance of pigs in a shuttle-box was modified by a Pavlovian fear-conditioning procedure. Diazepam (1 mg/kg) given before the Pavlovian conditioning session prevented the increase in corticosteroids and the impairment of performance in the subsequent test session before the presentation of the fear signal. Diazepam given before the Pavlovian conditioning session and/or the test session did not prevent the increase of response to the CS presentation; however, the temporal pattern of increase differed according to the drug condition: the diazepam treatment on the day of the test significantly delayed the peak of responding to the CS; in pigs treated with diazepam on the day of Pavlovian conditioning and with saline on the day of test, the increase of response was diffuse instead of being localized to the CS presentation period. Pigs treated with diazepam both during learning and performance of fear conditioning showed some evidence of performance facilitation. Usual unitary interpretations cannot account for such results which would appear to be the net result of several intermingled effects among which state-dependent learning, acquisition deficit, and performance facilitation seem to be of importance.

Adrenal Cortex Hormones↗
PubMed1975

[Sequential analysis of effectiveness of diazepam, a tranquilizer, on stress in swine (author's transl)].

To study the effectiveness of diazepam, a tranquilizer, in alleviating the problems resulting from the mixing and moving of weaned piglets from one piggery to another, two procedures, one of short-duration transport and the other of long-duration transport, are used in a double blind clinical trial. Both followed mixing the pigs, but before they entered the new piggery. Results from both groups of pigs (treated and control) are sequentially analyzed. Measurements used are growth rate and feed conversion curves during the first 18-20 days of the prefattening period. Diazepam (I mg/kg IM) reduces feed conversion when used to alleviate the effects of the long journey, but increases feed conversion after the short journey when compared to controls injected with a placebo. Worsening effects seem related to increased aggressiveness in animals treated and transported. These results indicate that a better understanding of the action mechanisms of psychotropic drugs is necessary, and they should be used with caution in husbandry.

Animal Feed↗