Influence of different adrenoceptor agonists and antagonists on physostigmine-induced yawning in rats

Propranolol in yawning prophylaxis: a case report

OBJECTIVE

Yawning is a frequent behavior with circadian effects. Sometimes, its frequency is very high and it is disturbing. However, there is no evidence-based treatment for yawning.

METHOD

This is a case report of a man with severe yawning from about 2 years ago.

RESULTS

Yawning reduced after taking propranolol.

CONCLUSION

Current evidence suggests that propranolol may decrease yawning through its thermoregulation effect. It is worthwhile conducting controlled clinical trials to study whether propranolol is an effective treatment for yawning.

Inhibitory effects of landiolol and nicardipine on thiopental-induced yawning in humans

PURPOSE

Either the calcium (Ca(2+))-channel blocker nicardipine or the beta(1)-adrenoceptor antagonist landiolol may be intravenously (IV) administered to reduce the hemodynamic responses to tracheal intubation. In this study, we examined the effects of these drugs on the yawning response elicited by intravenous thiopental in humans.

METHODS

After Institutional Review Board approval, 180 consenting American Society of Anesthesiologists (ASA) I or II patients undergoing elective surgery were recruited. In a double-blind, randomized design, three groups of 60 patients each received one of the following intravenous injections: (1) landiolol 0.1 mg/kg (L-group), (2) nicardipine 0.02 mg/kg (N-group), or (3) saline (S-group). In all patients, anesthesia was subsequently induced IV with 4 mg/kg thiopental. Thereafter, the occurrence of the yawning response (characterized by mouth opening) was continuously assessed as the only clinical endpoint for 1 min. Throughout the study, mean arterial blood pressure and heart rate were also recorded at 1-min intervals.

RESULTS

The incidence of the yawning response was lower in both the L-group (6.7%) and the N-group (16.7%) than in the S-group (46.7%) (each, P < 0.01).

CONCLUSIONS

Prior intravenous administration of either a Ca(2+)-channel blocker or a beta(1)-adrenoceptor antagonist can greatly reduce the thiopental-induced yawning response in humans.

Identification of independent predictors for intravenous thiopental-induced yawning

PURPOSE

To explore risk factors for the yawning response induced by the intravenous administration of thiopental during the induction of general anesthesia.

METHODS

We analyzed data from a cohort of 1322 patients who underwent elective surgery under general anesthesia plus intravenous thiopental. The data collected were: (a) the patients' demographic findings (age, sex, height, weight, cigarette smoking, hypertension, and presence of cerebral lesion), and (b) anesthesia-related findings (the kind of preanesthetic medication, i.e., atropine, epidural lidocaine, priming dose of vecuronium, fentanyl, and the dose of intravenous thiopental). An association between an individual variable in the evaluation model and the likelihood of thiopental-induced yawning behavior was characterized by means of the odds ratio. Multiple logistic regression was used to examine the independent contribution of each candidate variable, while controlling for all variables.

RESULTS

After the intravenous administration of thiopental, 461 patients exhibited a yawning response. The probability of this response was decreased by the prior use of intravenous fentanyl, by female sex, and by premedication with clonidine, but the probability was unaffected by premedication with hydroxyzine, by the prior use of atropine, or by the presence of hypertension or a cerebral lesion.

CONCLUSION

Thiopental-induced yawning may be suppressed by female sex, prior use of intravenous fentanyl, and premedication with clonidine. These findings may allow insights into the physiologic and pharmacological aspects of yawning in humans, thereby leading to the development methods to prevent thiopental-induced yawning.

Effects of imipramine on the expression and development of morphine dependence in mice

In the present study, the effects of imipramine and/or alpha-adrenoceptor agents on naloxone-induced jumping in morphine-dependent mice were examined. In the first set of experiments, the drugs were used before naloxone injection, to test their effects on the expression of jumping. Administration of imipramine (10-60 mg/kg) 15 min before naloxone increased the number of jumping in mice. Injection of the alpha2-adrenoceptor agonist, clonidine (0.1 mg/kg), or alpha1-adrenoceptor agonist, phenylephrine (4 mg/kg), themselves neither altered naloxone-induced jumping nor influenced the imipramine response. The alpha2-adrenoceptor antagonist, yohimbine (4 mg/kg), itself but not the alpha1-adrenoceptor antagonist, prazosin (1 mg/kg), increased jumping and decreased the imipramine effect. In the second set of experiments, imipramine and/or the alpha-adrenoceptor drugs were injected during the development of morphine dependence. Imipramine (10-40 mg/kg) increased the development of dependence and increased jumping was seen. Clonidine did not influence the imipramine effect. Phenylephrine was lethal in combination with imipramine. Both yohimbine and prazosin decreased the effect of imipramine. Imipramine and phenylephrine but not clonidine, yohimbine or prazosin decreased locomotion. It is concluded an alpha2-adrenoceptor mechanism may be involved in the influence of imipramine on the expression and development of naloxone-induced withdrawal signs in mice.

Morphine state-dependent learning: interactions with alpha2-adrenoceptors and acute stress

The interactions of -adrenoceptors and acute restraint stress with morphine state-dependent memory of passive avoidance were examined in mice. Memory acquired following pre-training morphine administration (5 mg/kg, i.p.) was dose- and time-dependently retrieved by pre-test morphine; this effect was reversible by yohimbine (1 mg/kg). Pre-test clonidine (0.005-0.1 mg/kg) was also effective in restoring morphine-induced memory. Pre-training clonidine (2 mg/kg) induced an amnestic effect that was restorable by pre-test clonidine or morphine; this effect was also blocked by yohimbine. Acute pre-training stress for 2 h induced an amnestic effect that was reversible by pre-test morphine (1 and 5 mg/kg) or clonidine (0.01 and 0.1 mg/kg). Finally, acute pre-test stress could restore the impairment of memory induced by pre-training morphine. The data are suggestive of a functional interaction between -opioid, -adrenergic receptors and stress in modulating state-dependent learning and memory.

The effects of dopamine receptor agents on naloxone-induced jumping behaviour in morphine-dependent mice

In the present study, the effects of dopamine receptor agonists and antagonists on naloxone-induced jumping in morphine-dependent mice were examined. Mice were rendered dependent as described in the methods section. Naloxone was injected to elicit jumping (as withdrawal sign). The first group received dopamine receptor drugs before naloxone injection to test the effects of the drugs on the expression of jumping. Administration of the dopamine D1/D2 receptor agonist, apomorphine (0.25, 0.5 and 1 mg/kg), decreased jumping, but not diarrhoea, induced by naloxone. The effect of apomorphine on jumping was reduced by the dopamine D2 receptor antagonist, sulpiride. The dopamine D2 receptor agonist, quinpirole (0.1, 0.3 and 0.5 mg/kg), increased jumping, while it decreased diarrhoea in mice. Different doses of sulpiride did not alter jumping, but one dose of the drug (12.5 mg/kg) decreased jumping. Neither the dopamine D1 receptor agonist, SKF38393 (1-phenyl-7,8-dihydroxy-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride; 8 and 16 mg/kg), nor the dopamine D1 receptor antagonist, SCH23390 (R-(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-benzazepine-7-ol maleate; 5, 10 and 25 mg/kg), altered jumping, but they decreased diarrhoea. The second group of animals received the drugs during the development of dependence. Administration of quinpirole (0.1, 0.3 and 0.5 mg/kg), but not bromocriptine (4, 8 and 16 mg/kg), apomorphine (0.25, 0.5, 1 and 2 mg/kg) or sulpiride (12.5, 25 and 50 mg/kg) decreased naloxone-induced jumping and diarrhoea. A dose of SKF38393 (8 mg/kg) decreased jumping, while both SKF38393 (4 and 16 mg/kg) and SCH23390 (5 and 10 microg/kg) increased diarrhoea. It is concluded that activation of both dopamine D1 and D2 receptors may suppress naloxone-induced jumping in morphine-dependent mice, and that stimulation of dopamine D1 receptors during development of morphine dependence may increase diarrhoea through peripheral mechanism.

The effects of simultaneous administration of alpha(2) -adrenergic agents with L-NAME or L-arginine on the development and expression of morphine dependence in mice

Both alpha(2)-adrenoceptors and the L-arginine/nitric oxide (NO) pathway have been implicated in the modulation of morphine dependence. This study examined the effects of simultaneous administration of the alpha(2)-adrenoceptor agonist clonidine or the antagonist yohimbine together with the NO precursor L-arginine or the NO synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on the induction and expression of morphine dependence as assessed by naloxone-precipitated withdrawal jumping and diarrhoea. Male NMRI mice weighing 20-30 g were used. In the induction phase, clonidine (0.01-0.1 mg/kg) intensified and yohimbine (0.5-2 mg/kg) attenuated the degree of morphine dependence. Yohimbine reversed the effect of clonidine. L-NAME (5 and 10 mg/kg) did not affect the development of morphine dependence, but significantly potentiated the effects of both subeffective (0.01 mg/kg) and effective (0.03 mg/kg) doses of clonidine. L-Arginine did not alter morphine dependence but inhibited the effect of clonidine. The effects of yohimbine in the induction phase were attenuated by L-NAME, but were not significantly affected by L-arginine. In the expression phase, clonidine attenuated and yohimbine intensified the signs of dependence. The effect of clonidine was inhibited by yohimbine. In the expression phase, L-NAME attenuated the withdrawal syndrome at 10 mg/kg and showed potentiation with clonidine in suppressing withdrawal signs. L-Arginine did not alter morphine dependence, but at 20 mg/kg inhibited and at 100 mg/kg potentiated the attenuating effect of clonidine on the expression of withdrawal syndrome. The effect of yohimbine on the expression phase was also attenuated by L-NAME, but was not significantly affected by L-arginine. In conclusion, alpha(2)-adrenergic and NO pathways seem to be functionally linked in the modulation of opioid dependence.

Involvement of adrenergic and cholinergic systems in nicotine-induced anxiogenesis in mice

In the present study, the effect of alpha-adrenoceptor agents on response to nicotine in an anxiety model (elevated plus-maze) in mice was investigated. Administered nicotine reduced indices of anti-anxiety behaviour (percent open-arm time (%open-arm time) and percent open-arm entries (%open-arm entry)) and increased indices of anxiety behaviour (protected stretched attention posture and percent of protected head dipping (%protected dipping)), indicating that nicotine elicits an anxiogenic response. This response to the drug was obtained 7 min but not 30 min after drug injection and with doses of 0.25 and 0.5 mg/kg. Nicotinic receptor antagonists mecamylamine (0.5 and 1 mg/kg) and hexamethonium (5 and 10 mg/kg) reduced the response induced by nicotine (0.25 mg/kg). Mecamylamine (1 mg/kg; decreased %open-arm entry and increased protected stretched attention posture) and hexamethonium (10 mg/kg; decreased %open-arm time) showed an anxiogenic-like profile. A muscarinic receptor antagonist, atropine (2.5 and 5 mg/kg), did not alter the nicotine response but elicited an anxiogenic effect by itself. The alpha(1)-adrenoceptor antagonist prazosin (0.25 and 0.5 mg/kg), but not the alpha(1)-adrenoceptor agonist, phenylephrine (4 and 6 mg/kg), reversed the nicotine effect. Single administration of phenylephrine (6 mg/kg) increased %open-arm time, while prazosin did not alter the anxiety behaviour. The alpha(2)-adrenoceptor agonist clonidine (0.001 and 0.01 mg/kg), induced complete immobility when administered in combination with nicotine. However, an alpha(2)-adrenoceptor antagonist, yohimbine (0.5 and 1 mg/kg), appeared to reverse the nicotine response, but did not show interaction with nicotine's effect. Clonidine did not elicit any effect, but yohimbine (1 mg/kg) increased %open-arm entry and %open-arm time by itself. It can be concluded that certain doses of nicotine (0.25 and 0.5 mg/kg) 7 min after their injection induce an anxiogenic effect through nicotinic mechanism(s), and that involvement of alpha(1)- but not alpha(2)-adrenoceptors in the response to nicotine seems likely.