Acute or chronic effects of cannabinoids on spontaneous or pharmacologically induced yawning in rats

Conditioned aversive responses produced by delayed, but not immediate, exposure to cocaine and morphine in male Sprague-Dawley rats

RATIONALE

To determine the conditions under which tastes paired with delayed access to experimenter-delivered cocaine and morphine elicit a conditionally aversive affective state.

OBJECTIVES AND METHODS

The potential of saccharin paired with immediate access to cocaine (5, 10, 20 mg/kg, sc and ip) and delayed (30 and 10 min) access to cocaine (20 mg/kg, sc and ip) and morphine (10 mg/kg, sc) to elicit a pattern of aversive responding in the taste reactivity test (Grill and Norgren 1978a) was evaluated. Cocaine-induced aversions were compared with those produced by a moderate dose of LiCl (50 mg/kg). Finally, as an independent measure of cocaine withdrawal, the potential of exposure to saccharin paired with delayed access to cocaine to produce anxiogenic-like responding in the Light-Dark Emersion test was evaluated.

RESULTS

Immediate access to cocaine did not produce conditioned aversion at any dose. Delayed (30 or 10 min) access to sc cocaine (20 mg/kg) produced robust conditioned aversion and delayed access to ip cocaine (20 mg/kg; 30 min) and to sc morphine (10 mg/kg; 10 min) produced weaker conditioned aversion. Yawning emerged as a potential withdrawal response in rats conditioned with delayed (30 min) access to 20 mg/kg, sc, cocaine. Contextual cues did not produce conditioned aversion when paired with delayed access to sc cocaine (20 mg/kg). Finally, exposure to saccharin paired with delayed access to cocaine produced anxiogenic-like responding in the Light-Dark Emersion test.

CONCLUSION

Our results support the contention that a conditioned aversive state develops when a taste cue comes to predict the delayed availability of drugs of abuse.

Yawning elicited by intravenous ethanol in rhesus monkeys with experience self-administering cocaine and ethanol: Involvement of dopamine D3 receptors

Characterization of the effects of long-term alcohol consumption on the brain would be aided by the development of behavioral assays that are relatively easy to implement in animal models of alcohol use disorders. Assessing unconditioned behaviors, such as drug-elicited yawning in models that permit long-term alcohol ingestion, may be a valuable complement to more invasive and costly procedures. The present studies investigated previous unexpected findings of ethanol-induced yawning in nonhuman primates. Subjects were adult male rhesus monkeys (n = 8), all of which had experience self-administering intravenous cocaine for several years. Four monkeys also had experience consuming 2.0 g/kg ethanol over 1 h per day, 5 days per week, for 6.8-12.0 months. All monkeys received saline or ethanol (0.25-1.0 g/kg) infused intravenously (i.v.) over 10 min, and the number of yawns elicited during the infusion was counted. A second experiment in the ethanol-experienced monkeys examined whether ethanol-induced yawning could be blocked by PG01037 (1.0, 3.0 mg/kg, i.v.), a selective antagonist at dopamine D3 receptors (D3R). Ethanol significantly and dose-dependently increased yawns in the ethanol-experienced animals, but not the ethanol-naïve animals. In the ethanol-experienced monkeys, this effect of ethanol was blocked by the D3R antagonist. The pharmacology of yawning is complex and a good deal of model development remains to be performed to characterize the potential involvement of other neurotransmitter systems. Nonetheless, drug-elicited yawning may be a useful unconditioned behavioral assay to assess the effects of long-term alcohol consumption in established nonhuman primate models.

Yawning-Its anatomy, chemistry, role, and pathological considerations

Yawning is a clinical sign of the activity of various supra- and infratentorial brain regions including the putative brainstem motor pattern, hypothalamic paraventricular nucleus, probably the insula and limbic structures that are interconnected via a fiber network. This interaction can be seen in analogy to other cerebral functions arising from a network or zone such as language. Within this network, yawning fulfills its function in a stereotype, reflex-like manner; a phylogenetically old function, preserved across species barriers, with the purpose of arousal, communication, and maybe other functions including respiration. Abnormal yawning with ≥3 yawns/15min without obvious cause arises from lesions of brain areas involved in the yawning zone, its trajectories causing a disconnection syndrome, or from alteration of network activity by physical or metabolic etiologies including medication.

Paradoxical sleep deprivation: neurochemical, hormonal and behavioral alterations. Evidence from 30 years of research

Sleep comprises approximately one-third of a person's lifetime, but its impact on health and medical conditions remains partially unrecognized. The prevalence of sleep disorders is increasing in modern societies, with significant repercussions on people's well-being. This article reviews past and current literature on the paradoxical sleep deprivation method as well as data on its consequences to animals, ranging from behavioral changes to alterations in the gene expression. More specifically, we highlight relevant experimental studies and our group's contribution over the last three decades.

Potentiation of penile erection and yawning responses to apomorphine by cannabinoid receptor antagonist in rats

The effect of systemic administration of the cannabinoid antagonist SR 141716A (N-(piperidin-1-yl)-5-(4-chlorophenyl)-4-methyl-1H-pyrazole-3-carboxyamide) on penile erection and yawning induced by apomorphine was investigated in rats. SR 141716A (2 mg/kg, i.p.) administered 40 min before apomorphine (40 and 80 microg/kg, s.c.) increased the number of penile erection and yawning responses. The administration of cannabinoid agonist Delta9-tetrahydrocannabinol (1.25 mg/kg, i.p.) 15 min before apomorphine (40 and 80 microg/kg, s.c.) did not affect penile erection, however it decreased yawning. The present results provide additional evidence that cannabinoid agonists interfere with dopaminergic systems and that SR 141716A together with a dopaminergic agonist could be useful to potentiate dopaminergic activity.