Chlordiazepoxide (librium)-induced changes in intraspecific attack and selected non-agonistic behaviors in male Siamese fighting fish

Effect of drugs that alter alertness and emotionality on the novelty response of a weak electric fish, Gymnotus carapo

Weak field electric fish respond to alerting stimuli with a transient increase in the frequency of electric organ discharge (novelty response). In an attempt to demonstrate the influence of different degrees of alertness and of emotionality on the novelty response of Gymnotus carapo, we studied the variations in the magnitude of this response induced by the application of an electric stimulus to the water of the experimental box using a pair of electrodes, before and after intramuscular injections of d-amphetamine (1-2 and 4 mg/kg), sodium pentobarbital (10-20 and 30 mg/kg), diazepam (1-2 and 4 mg/kg), beta-carboline (2 mg/kg), and saline. After d-amphetamine injection the animal presented increased somatic motility but no changes in electric organ baseline firing rate or in response to the alerting electric stimulus. Sodium pentobarbital induced a partial loss of posture and a reduction of fin and operculum movements, as well as a reduction of baseline firing rate and of the response to the alerting electric stimulus, with frequent interruptions in electric organ firing. Beta-carboline caused increased motility, but no changes in basal firing rate or in response to the alerting stimulus. Diazepan-injected fishes remained still throughout the experiment, and some of those threated with the higher dose (4 mg/kg) presented interruptions on electric organ discharges in response to stimulation but no change on baseline firing rate. The data suggest that a reduction of the degree of alertness by the barbiturate and a decrease in emotionality and/or stress by the benzodiazepine interfere with the novelty response. The possible site of action of the drugs is discussed.

Brain benzodiazepine receptors in fathead minnows and the behavioral response to alarm pheromone

Fathead minnows (Pimephales promelas) exposed to 1 or 10 mg/l chlordiazepoxide showed normal alarm behavior during the presentation of alarm pheromone. Fish exposed to 20 mg/l drug, however, showed little or no behavioral alarm and did not appear sedated. A food extract stimulus presented after alarm pheromone led to a large foraging response by fish exposed to 20 mg/l chlordiazepoxide. Control fish or fish exposed to 1 to 10 mg/l drug showed less tendency to begin foraging. Exposure to 1, 10, or 20 mg/l chlordiazepoxide for 3 hr did not affect whole-brain concentrations of tryptophan, 5-hydroxytryptamine, 5-hydroxyindoleacetic acid, tyrosine, or dopamine. The binding of [3H]diazepam to specific brain receptor sites (KD = 10 nM, estimated Bmax = 3.3 fmol/mg wet weight) could be displaced by chlordiazepoxide (IC50 = 1.6 microM). These results suggest that benzodiazepine receptors in the central nervous system of lower vertebrates may function in ways similar to those in mammals, i.e., in the modulation of behavior in anxiety-like states.

Effects of ethanol and naltrexone on aggressive display in the siamese fighting fish, Betta splendens

The present study used the aggressive display of Betta splendens in response to a mirror as an index of the effects of ethanol and the opiate antagonist, naltrexone. Naltrexone produces an opiate receptor blockade and thus provided a test of the hypothesis that ethanol effects on aggression are mediated by the opioid system. Eighty fish were randomly assigned to one of eight groups in a 4 X 2 factorial design with Ethanol (0, 0.25, 0.50, and 0.75 g%) and Naltrexone (0 and 5 mg/l) as the main factors. The 0.75 g% dose of ethanol reliably suppressed aggressive display as measured by number of gill show responses, but lower doses had no effect or tended to increase aggressive display. At the same time, all doses of ethanol increased arousal in the fish as measured by airgulping. Naltrexone alone did not have effects on aggression or arousal, and did not interact with ethanol on either measure. Thus the results did not support the ethanol-opioid common-link hypothesis.

Benzodiazepines and their antagonists: a pharmacoethological analysis with particular reference to effects on "aggression"

A review of the literature on chlordiazepoxide indicates that the traditional view of benzodiazepines as antiaggressive drugs represents an inaccurate generalization. In fact, highly variable findings have been reported with the most significant factor in the variability being the type of aggression studied. Furthermore, considerable controversy surrounds the nature of chlordiazepoxide's influence on social conflict in rodents, with opinion divided regarding the selectivity of its inhibitory effect on offensive responding. It is argued that inappropriate behavioural methodology may have substantially contributed to this controversy. A pharmacoethological approach to the analysis of drug effects on social behaviour is described and exemplified by new data on chlordiazepoxide and midazolam. Both agents inhibit offense at doses which do not result in general response inhibition, yet their overall behavioural profiles are somewhat different. Evidence is also presented indicating low dose behavioural activity of the benzodiazepine antagonist Ro15-1788 in two test situations and suggesting possible differences in the effects of Ro15-1788 and CGS8216 on novelty-related responding. Several avenues of research are discussed which may yield insights into the manner whereby benzodiazepines influence social patterns and the significance of benzodiazepine-GABA interactions in such processes.

Benzodiazepine receptors in fish brain: [3H]-flunitrazepam binding and modulatory effects of GABA in rainbow trout

We have identified and partially characterised benzodiazepine binding sites in whole brain membranes of male rainbow trout. In terms of Bmax and KD values trout brain receptors are remarkably similar to those in rat and human brain. The Hill coefficient was 0.98, indicating a single binding site. GABA (10(-4) M) was able to significantly elevate binding of [3H]-FNZ through a change in KD rather than Bmax. This effect was prevented by the GABA receptor antagonist bicuculline methiodide.

Comparative psychopharmacology

Studies of the effects of psychoactive drugs and neurotransmitters on the behavior of invertebrates and poikilothermic vertebrates are reviewed. Dangers of reductive explanations are pointed out. Results and suggestions are given concerning the use of poikilothermic animals (1) in the development of screening tests, (2) in experiments on the action mechanisms of psychopharmaca, and (3) in the use of psychoactive drugs in the study of the mechanisms of animal behavior.

Pentobarbital sodium and attack behavior in male Siamese fighting fish

An experiment was undertaken to determine the effects of pentobarbital sodium on intraspecific attack behavior in male Siamese fighting fish in an attempt to extend earlier findings with chlordiazepoxide and secobarbital sodium. Pairs of fish fought while immersed in 20 microgram/ml or 40 microgram/ml pentobarbital sodium or plain water. The 40 microgram/ml group showed significantly less attack (e.g., biting, jaw locking) than either control or low dose groups without producing a change in general arousal. Quasisexual behavior, seen in an earlier chlordiazepoxide study, did not occur in the present study.

Effects of psychotropic drugs upon the hypothalamic rage response in cats

Effects of Chlorpromazine (CPZ), Haloperidol (HLP), Pentobarbital (PTB), and Diazepam (DZP) upon thresholds of the hypothalamically elicited rage response, i.e., directed attack and treat responses, were studied in chronic cats. All these drugs elevated the directed attack thresholds. CPZ and HLP elevated also the threat response thresholds and produced ataxia, but DZP did not show these effects. From these results, it is suggested that CPA and HLP suppressed the amygdalo-ventromedial hypothalamic nuclear and cerebellar functions and DZP suppressed the afferent pathway of the direct attack. PTB showed intermediate effects between the above two groups.