The effects of chlordiazepoxide (Librium) on the intensity and habituation of agonistic behavior in male Siamese fighting fish

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.

Maintained aggressive behavior in gonadectomized male Siamese fighting fish (Betta splendens)

Adult male Betta splendens were gonadectomized and tested twice for aggressive behavior two weeks later. In a mutual viewing test environment, it was found that gonadectomized animals maintained their aggressive behavior on all six indices of aggression at a level equal to controls. Animals that showed some testis regeneration and sham operated fish were also equal to controls. The results are interpreted to mean that adult aggressive behavior in male B. splendens may not be under the control of gonadal hormones. Pituitary gonadotropins, interrenal gland, and critical period hypotheses are given as possible explanations of the maintained aggressiveness following castration.

The effects of lithium chloride on response to salient and nonsalient stimuli in Carassius auratus

The exploratory behaviour of 20 goldfish was investigated to see whether it was affected by treatment with lithium chloride. When familiar and novel stimuli were readily discriminable, lithium treatment had no effect on exploration. In a second study, using 20 fish, it was shown that when novel and familiar stimuli were less markedly different from each other, exploratory responses to the novel stimulus were reduced by lithium. The findings may be related to a general suppressant action of lithium on the extent of stimulus generalisation, or to a reduction by lithium of the animals' responsiveness to near-threshold levels of stimulation.

Effects of two anxiolytics on distraction, habituation and dishabitiuation

Rats were engaged in a baseline activity of licking and their distraction to tone stimuli measured by an interruption in licking. Habituation, distraction to a stimulus change and dishabitiuation (the return of distraction to the original tone) were studied. Ethanol (0.4 and 0.8 g/kg) and chlordiazepoxide (7.5 mg/kg) produced significantly faster habituation, a result that cannot be attributed to changes in the baseline response rate, or to differences in the initial distraction to the tone. All groups showed 24 hr retention to the tone when they were tested in the same state in which they were habituated. There was transfer of habituation between drugged and undrugged states for rats injected with chlordiazepoxide, but rats habituated undrugged showed no retention if tested after injections of ethanol. Chlordiazepoxide impaired the specificity with which the physical parameters were coded, whereas ethanol improved the specificity of coding. Neither drug affected dishabituation.

Effects of clonidine on habituation and sensitization of acoustic startle in normal, decerebrate and locus coeruleus lesioned rats

Rats were presented with startle-eliciting tones after injection of clonidine (0.01, 0.02, 0.04, 0.08, 0.5, 1.0 or 2.0 mg/kg) or saline. Clonidine potently depressed startle amplitude and the effect was monotonically related todose. Pretreatment with piperoxane (10 mg/kg) antagonized this effect but pretreatment with phentolamine (10 mg/kg) did not. Clonidine still depressed startle in acutely decerebrate rats and in rats with bilateral ablation of the locus coeruleus. Clonidine did not interfere with sensitization to background noise and did not interfere with the ability to startle but instead improved within-session habituation. The results represent one of the few instances in the literature where a drug appears to improve habituation without directly interfering with the ability to respond. The possibility that clonidine might affect startle by stimulating central epinephrine rather than norepinephrine receptors is discussed.

Pheromonal control of aggressive display in siamese fighting fish (Betta splendens)

Male Siamese fighting fish displayed and respirated from the surface more frequently in water containing secretions collected from non-displaying male conspecifics than they did in clean water. Secretions collected from males given the opportunity to display to a mirror for 16, 30, or 45 min. did not affect display activity. However, secretions collected from males allowed to display to a mirror for 16 min. produced an increase in respiration rates. Secretions collected from males which had been stressed by electric shock resulted in decrements in aggressive display. Taken together, results of these experiments suggest that male Siamese fighting fish secrete substances which affect mirror-induced aggression and respiration rates.

Differentiation by morphine of two types of aggressive behaviour in the convict cichlid (Cichlasoma nigrofasciatum)

Morphie sulfate (5 mg/l and 10 mg/l) significantly decreased the amount of territorial aggression in the convict cichlid (Cichlasoma nigrofasciatum). The same doses had no effect on predatory aggression (ingestion of brine shrimp). The data suggest that previously demonstrated morphine receptor in the fish has functional properties.

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

Two experiments were undertaken to determine the effects of chlordiazepoxide on intraspecific attack behavior and selected non-aggressive behaviors in male Siamese fighting fish. In Exp. 1, pairs of fish fought while immersed in either 15 mug/ml or 30 mug/ml of chlordiazepoxide, or plain water. The drug groups showed significantly less attack (e.g., biting, jawlocking) than the control group, without noticeable behavioral toxicity. Also, in the drug groups alone, some variants of the copulatory clasp, seen in normal mating, occurred in many pairs. In Exp. 2, individual fish were isolated in one of the same doses or plain water for a period equivalent to that of Exp. 1. These doses produced no changes in measures of arousal, locomotion, and feeding behavior, as compared to the control condition. The drug-related appearance of the intermale mating-like behavior is discussed in terms of a theoretical formulation postulating a mutually inhibitory relationship between sex and aggression in fish.