Clonazepam-induced up-regulation of serotonin1 binding sites in frontal cortex of rat

Clonazepam: Indications, Side Effects, and Potential for Nonmedical Use

After participating in this activity, learners should be better able to:• Assess the misuse potential of clonazepam• Characterize the nonmedical use of clonazepam• Identify the health problems associated with long-term use of clonazepam ABSTRACT: Clonazepam, a benzodiazepine, is commonly used in treating various conditions, including anxiety disorders and epileptic seizures. Due to its low price and easy availability, however, it has become a commonly misused medication, both in medical and recreational contexts. In this review, we aim to highlight the behavioral and pharmacological aspects of clonazepam and its history following its approval for human use. We examine the circumstances commonly associated with the nonmedical use of clonazepam and raise points of particular concern. Clonazepam, alone or in combination with other psychoactive substances, can lead to unwanted effects on health, such as motor and cognitive impairment, sleep disorders, and aggravation of mood and anxiety disorders. Prolonged use of clonazepam may lead to physical dependence and tolerance. There is therefore a need to find safer therapeutic alternatives for treating seizures and anxiety disorders. Greater awareness of its frequent nonmedical use is also needed to achieve safer overall use of this medication.

Pharmacological treatment of childhood obsessive-compulsive disorder: from theory to practice

Discusses pharmacological treatment of childhood obsessive-compulsive disorder (OCD), chronic and underrecognized psychiatric condition that affects up to 2% to 3% of children and adolescents. Research in OCD in children, including neuropharmacology, brain imaging, genetics, and clinical phenomenology, informs current views of OCD pathophysiology. Contemporary research supports the notion of a dysregulation in serotonin subsystems in the central nervous system, with target areas of dysfunction including basal ganglia and orbitofrontal cortex. Pharmacotherapy, along with cognitive-behavioral approaches, constitutes the indicated treatment for childhood OCD. Pharmacological treatment is best guided by a phenomenological understanding of the type of obsessions and compulsions, the intensity and frequency of their presentation with attention to behavioral reinforcements, and psychosocial factors that affect the course of the disease. Serotonin-enhancing agents, such as fluoxetine, fluvoxamine, paroxetine, and sertraline and citalopram (SSRIs) are first-line pharmacological agents, whereas refractory symptoms can be treated by augmentation with neuroleptics or other agents. Clomipramine is as effective as the SSRIs but its use may be accompanied by increased side effects. Genetic factors probably influence susceptibility to OCD as well as response to treatment, and the elucidation of these and other risk factors will be important elements in the future understanding and treatment of this disorder.

Effects of chronic diazepam treatment on pre- and postsynaptic 5-HT1A receptors in the rat brain

Biochemical and electrophysiological approaches were used to assess possible changes in 5-HT1A receptors in the rat brain after long-term treatment with an anxiolytic benzodiazepine. Rats were treated with diazepam (2 mg/kg i.p. daily) during 14 days and then untreated for 1 day (protocol A) or 5 days (protocol C) until they were killed for in vitro investigations on 5-HT1A receptors. In addition, other rats (protocol B) received the same 14-day treatment with diazepam, followed by 1 mg/kg of the drug on days 15 and 16, and 0.5 mg/kg on days 17 and 18, and were killed 24 h after the last injection. In vitro binding and quantitative autoradiographic experiments with [3H]8-hydroxy-2-(di-n-propylamino)tetralin ([3H]8-OH-DPAT) showed that the characteristics of 5-HT1A receptor binding sites in the hippocampus and the dorsal raphe nucleus were not significantly altered by the administration of diazepam under the treatment protocols A, B and C. Furthermore, in vitro electrophysiological recordings of serotoninergic neurons in the dorsal raphe nucleus of brain stem slices revealed no modification in the sensitivity of somatodendritic 5-HT1A autoreceptors in rats treated with diazepam according to the protocols A and B. However, under the conditions of protocol C, the potency of 8-OH-DPAT to depress the firing rate of serotoninergic neurons was significantly enhanced, as expected of a hypersensitivity of somatodendritic 5-HT1A autoreceptors. These data support the hypothesis that some functional changes in these receptors could occur during benzodiazepine withdrawal. However, they do not support the idea of a reduced anxiolytic efficacy of 5-HT1A receptor agonists as a result of prior treatment with a benzodiazepine.

Clonazepam as an augmenting agent in the treatment of childhood-onset obsessive-compulsive disorder

This case study is of a young man with childhood onset of severe obsessive-compulsive disorder (OCD). The patient had no clinical improvement during therapeutic trials of clomipramine, fluoxetine, and fluvoxamine, including buspirone augmentation. The patient consumed 50 tablets of fluoxetine in a suicide attempt and experienced a total remission of his OCD symptoms for the first time in his life. This remission lasted approximately 1 month and raises interesting questions about the mechanism of action of the serotonin reuptake inhibitors. Subsequently, the patient was able to achieve a 75% improvement in symptomatology when treated with a combination of fluoxetine and clonazepam. This open report suggests that clonazepam may be an effective augmentation agent to a serotonin reuptake inhibitor in the treatment of OCD.

Potentiation of physical dependence on diazepam by ondansetron in rats

The effects of ondansetron, a 5-HT3 antagonist, on the development of physical dependence on diazepam were examined in rats using a drug-admixed food method. Rats were treated with diazepam or diazepam in combination with ondansetron for 26 days. After an abrupt withdrawal from diazepam, the incidence of withdrawal signs, such as jerks, tremors and convulsions, and withdrawal scores, were potentiated by co-administration of ondansetron. On the other hand, rats which had been treated with ondansetron alone for 33 days did not show any withdrawal signs after abrupt withdrawal from ondansetron. These findings suggest that ondansetron does not possess physical dependence liability, but does potentiate the development of physical dependence on diazepam. Regulation of serotonergic neurons through 5-HT3 receptors may affect the development of physical dependence on diazepam.

Milacemide increases 5-hydroxytryptamine and dopamine levels in rat brain--possible mechanisms of milacemide antimyoclonic property in the p,p'-DDT-induced myoclonus

Milacemide, a glycine prodrug that is able to enter the brain readily, has been shown to have an antimyoclonic property in the p,p'-DDT-induced myoclonus syndrome. Milacemide increased regional 5-HT and dopamine and decreased 5-HIAA, DOPAC and HVA levels in naive rats. In p,p'-DDT-treated rats, 5-HT levels were unchanged at the time the rats experienced spontaneous myoclonus in all brain regions except in the striatum, where it increased. 5-HIAA levels increased but did not reach significant levels except in the striatum. Dopamine, DOPAC, HVA and norepinephrine were unchanged. When rats were treated concurrently with both p,p'-DDT and milacemide, regional 5-HT levels were increased and NE levels in the brainstem and cerebellum decreased. Depletion of brain serotonin by pretreatment with PCPA or with 5,7-DHT, or blocking 5-HT receptors with different 5-HT antagonists, failed to eliminate the antimyoclonic property of milacemide. This antimyoclonic effect of milacemide may be mediated through other mechanisms besides its ability to increase brain 5-HT levels. Possible mechanisms to be considered are its antiepileptic property, and its ability to increase brain glycine levels. Milacemide may have potential for therapeutic trials in patients with myoclonus.