Autoradiographic localization and pharmacological characterization of [3H]tandospirone binding sites in the rat brain

5-HT1A receptor-dependent modulation of emotional and neurogenic deficits elicited by prolonged consumption of alcohol

Repeated episodes of binge-like alcohol consumption produce anxiety, depression and various deleterious effects including alterations in neurogenesis. While the involvement of the serotonin receptor 1 A (5-HT1A) in the regulation of anxiety-like behavior and neurogenesis is well documented, its contribution to alcohol withdrawal-induced anxiety and alcohol-induced deficits in neurogenesis is less documented. Using the Drinking-In-the-Dark (DID) paradigm to model chronic long-term (12 weeks) binge-like voluntary alcohol consumption in mice, we show that the selective partial activation of 5-HT1A receptors by tandospirone (3 mg/kg) prevents alcohol withdrawal-induced anxiety in a battery of behavioral tests (marble burying, elevated-plus-maze, open-field), which is accompanied by a robust decrease in binge-like ethanol intake (1 and 3 mg/kg). Furthermore, using triple immunolabelling of proliferation and neuronal differentiation markers, we show that long-term DID elicits profound deficits in neurogenesis and neuronal fate specification in the dorsal hippocampus that are entirely reversed by a 2-week chronic treatment with the 5-HT1A partial agonist tandospirone (3 mg/kg/day). Together, our results confirm previous observations that 5-HT1A receptors play a pivotal role in alcohol drinking behavior and the associated emotional and neurogenic impairments, and suggest that 5-HT1A partial agonists represent a promising treatment strategy for alcohol abuse.

Role of tandospirone, a 5-HT1A receptor partial agonist, in the treatment of central nervous system disorders and the underlying mechanisms

5-hydroxytryptamine (5-HT, serotonin) is an important neurotransmitter in the modulation of the cognitive, behavioral and psychological functions in animals and humans. Among the fourteen subtypes of 5-HT receptor, 5-HT1A receptor has been extensively studied. Tandospirone, an azapirone derivative with strong and selective agonist effect on 5-HT1A receptor, has been used for the treatment of anxiety disorders especially generalized anxiety disorder for decades. Recently, tandospirone showed the efficacy in relieving the syndromes of social anxiety disorder and post-traumatic stress disorder as well as in potentiating the effect of antidepressants in the treatment of depression in both preclinical and clinical studies. More impressively, the beneficial effect of tandospirone has been revealed on improvement of motor dysfunction of Parkinson's disease and cognitive deficits of schizophrenia either in monotherapy or in combination with other drugs. This review discusses the superiority of tandospirone in the treatment of the disorders and associated mechanisms in central nervous system from the literature.

A Review of Pharmacological Treatments for Depression in Alzheimer's Disease

Depression in Alzheimer's disease (dAD) is one of the most common behavioral and psychological symptoms of dementia, with devastating consequences not only for the affected individuals, but for caregivers as well. So far, pharmacological treatment of dAD has been based on the "monoamine hypothesis". However, the reported moderate effects of approved antidepressants, as well as an increasing body of research evidence, suggest a more complex pathophysiologic mechanism. In the present paper, a systematic review of different treatments for dAD is presented that can inform the study of alternative neuropathological and neurobiological aspects of the disease aimed at the development of more effective treatment targets.

Clinical evaluation of the efficacy and safety of tandospirone versus sertraline monotherapy for social anxiety disorder: a randomized open-label trial

OBJECTIVE

Although selective serotonin reuptake inhibitors are now established as first-line pharmacotherapy for social anxiety disorder (SAD), other agents with different mechanisms have shown promise in treating SAD. The aim of this study was to examine the efficacy and safety of tandospirone in treating adolescents with SAD.

METHODS

Adolescent patients meeting the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for SAD were randomly assigned (1:1) to open-label treatment with either tandospirone or sertraline for 8 weeks. The primary outcome measures were changes from baseline in the Hamilton Anxiety (HAM-A) scale and response using the Clinical Global Impression of Improvement (CGI-I) scale.

RESULTS

The adjusted mean change in HAM-A scores from baseline was indicating a significant improvement over baseline in both treatment arms (p < 0.0001). The mean CGI-I scale score at week was with no significant difference between the two arms (p = 0.42). Rates of response were 48.6% for tandospirone and 55.6% for sertraline using the CGI-I. Response rates were 37.1% for tandospirone and 41.7% for sertraline using a HAM-A response criterion (≥50% reduction). The adjusted mean change in Social Phobia Inventory scores from baseline was indicating a significant improvement over baseline in both treatment arms (p < 0.0001).

CONCLUSIONS

Tandospirone is safe and effective and appears non-inferior to sertraline for SAD in youths.

Effects of selective 5-HT1A agonist tandospirone on the rate and rhythmicity of binocular rivalry

RATIONALE

When dissimilar figures are presented to each eye individually, perception alternates spontaneously between each monocular view. This phenomenon, binocular rivalry, has been suggested to depend on serotonergic neural systems.

OBJECTIVE

To investigate the relationship between binocular rivalry and serotonergic neural systems in more detail, we measured the perceptual alternation rate and rhythmicity of binocular rivalry under the influence of the 5-HT(1A) agonist tandospirone.

MATERIALS AND METHODS

Fifteen healthy volunteers were tested under placebo and 60 mg tandospirone conditions using the single-blind method. The perceptual alternation rate and rhythmicity of binocular rivalry were measured at pre-administration and at 90, 180, and 360 min post-administration.

RESULTS

Compared to placebo, the administration of tandospirone decreased the rate and rhythmicity of perceptual switching significantly at 90 and 180 min post-administration in a manner that is consistent with its pharmacokinetics.

CONCLUSIONS

The present results suggest that the 5-HT(1A) neural pathways, mainly located in the mesolimbic system and brainstem, may play a crucial role as an oscillator in perceptual rivalry alternations.

The pharmacokinetics and pharmacodynamics of tandospirone in rats exposed to conditioned fear stress

The 5-HT1, agonist tandospirone is generally thought to have a weak anxiolytic effect with a slow onset of action. Our recent clinical study suggested that a comparatively high dose of tandospirone has excellent anxiolytic efficacy and is without significant adverse effects. The present study was designed to clarify the relationship between the anxiolytic effect of tandospirone and its plasma and brain concentrations. The anxiolytic effect was estimated by determining the conditioned fear stress-induced freezing behavior in rats after tandospirone administration. Obvious correlations between anxiolytic effect and brain concentration of tandospirone were observed 0.5 and 4 h after tandospirone administration, while the anxiolytic effect was dependent on the plasma concentration of at 0.5 h but not 4 h after tandospirone administration. The plasma concentration was significantly correlated with the brain concentration. These findings suggest that the potency of the anxiolytic effect is dependent on both the plasma and brain concentration.

The effect of tandospirone, a serotonin(1A) agonist, on memory function in schizophrenia

BACKGROUND

The purpose of this study was to test the hypothesis that the addition of tandospirone, a 5-HT(1A) partial agonist, to ongoing treatment with typical antipsychotic drugs, would improve memory function in patients with schizophrenia.

METHODS

Eleven outpatients (male/female = 7/4) with schizophrenia who had been on stable doses of haloperidol and biperiden were given tandospirone, 30 mg/day, for 4 weeks. The Wechsler Memory Scale-Revised (WMS-R) was administered at baseline and 4 weeks after the addition of tandospirone. The Brief Psychiatric Rating Scale (BPRS; Total, Positive, and Negative subscale scores) and the Simpson-Angus Scale for Extrapyramidal Symptoms (SAS) were also completed on the two occasions. To exclude the possibility of a practice effect on the WMS-R test, 11 age-matched patients with schizophrenia (M/F = 7/4) were tested at baseline and after a 4-week interval.

RESULTS

Repeated measures analysis of variance revealed a significant time by group (patients with or without tandospirone) effect for the Verbal-, but not the Visual Memory composite scores of the WMS-R test; no significant change was observed in patients without tandospirone, whereas improvement in the Verbal Memory score was noted in patients receiving tandospirone. Moreover, there was improvement in the Inclusion score, an index of memory organization as measured by the Logical Memory subtest of WMS-R, only in patients with tandospirone. Scores on the BPRS and SAS were improved during treatment with tandospirone, but the effects did not reach statistical significance.

CONCLUSIONS

The results suggest that adjunctive treatment with 5-HT(1A) agonists may improve some types of memory function in schizophrenia.

Localization and pharmacological characterization of [3H]perospirone-binding sites in rat brain

1. The regional distribution and pharmacological property of binding sites for perospirone, an atypical neuroleptic, in rat brain were examined by an in vitro binding assay. 2. A high degree of [3H]perospirone binding was observed in the frontal cortex, caudate putamen, nucleus accumbens, olfactory tubercle, lateral septum, choroid plexus, hippocampus and entorhinal cortex. 3. In cortical membranes, the frontal cortex and nucleus accumbens, 1 nM [3H]perospirone bound predominantly to serotonin 5-HT2A receptors (about 40% of specific [3H]perospirone binding) rather than to dopamine D2 receptors. 4. About 60% of binding sites specifically labeled with 1 nM [3H]perospirone were D2 receptors and about 20% were 5-HT2A receptors in striatal membranes and the caudate putamen. 5. [3H]Perospirone interacted mainly with 5-HT1A receptors in hippocampal membranes and the lateral septum. 6. These results suggest that perospirone has a broad binding activity and that predominant occupancy of 5-HT2A receptors in mesocortical and mesolimbic structures might concern the atypical profile of perospirone as an antipsychotic drug.

Differential effects of haloperidol and two anxiolytic drugs, buspirone and lesopitron, on c-Fos expression in the rat striatum and nucleus accumbens

We have studied the effects of the neuroleptic haloperidol and the non-benzodiazepine anxiolytics buspirone and lesopitron on the expression of c-Fos immunoreactivity in the rat forebrain. Haloperidol and buspirone administration resulted in a significant quantitative increase in the number of Fos-immunoreactive neurons in the lateral striatum and a presumable qualitative increase in the nucleus accumbens. In contrast, lesopitron did not lead to a significant increase in the c-Fos expression in the striatum. The induction of c-Fos immunoreactivity by buspirone is compatible with an interaction of this compound with D2 dopamine receptors, as documented for haloperidol. The lack of effects after lesopitron administration suggests that, in contrast with buspirone, this compound has no dopaminergic blocking activity.

Effects of tandospirone on second messenger systems and neurotransmitter release in the rat brain

1. We studied the effects of tandospirone, a novel serotonin (5-HT)1A receptor-related anxiolytic, on the intracellular second messenger systems and neurotransmitter release. 2. Tandospirone inhibited forskolin-stimulated adenylate cyclase activity in rat hippocampal membranes by activation of 5-HT1A receptors and had high efficacy comparable to 5-HT1A receptor agonists such as 5-HT and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). 3. Tandospirone suppressed carbachol-stimulated phosphatidyl-inositol metabolism (PI response), which was shown to be a 5-HT1A receptor-mediated event. 4. Tandospirone did not affect the release of 5-HT, norepinephrine (NE), dopamine (DA) and acetylcholine (ACh) from rat brain slice preparations. 5. These findings suggested that tandospirone shows high agonistic efficacy on the postsynaptic 5-HT1A receptors but does not affect the presynaptic autoreceptors located on nerve endings. The modulation of the second messenger system via postsynaptic 5-HT1A receptors might be involved in the anxiolytic efficacy of tandospirone.

Effects of tandospirone in three behavioral tests for anxiolytics

The azapirone putative anxiolytic tandospirone was evaluated in two behavioral screening methods that identify known azapirone anxiolytics and one method that identifies only sedative-hypnotic anxiolytics. Tandospirone produced a large increase in punished key-pecking for food in pigeon and a large increase in cork gnawing in rat. It did not produce a large increase in punished lever-pressing for food in rat, a result that to some extent contradicts reports from other laboratories. It was equipotent with buspirone in pigeon, but in rat it was ten times less potent than buspirone in disrupting the lever-press response and increasing cork gnawing. The results indicate that tandospirone is qualitatively similar to the other azapirone anxiolytics buspirone, gepirone and ipsapirone and is different from sedative-hypnotic anxiolytics.

Serotonergic Mechanisms in Anxiolytic Effect of Tandospirone in the Vogel Conflict Test

To clarify which 5-HT1A receptors, autoreceptors located in the raphe nuclei or post-synaptic receptors in the forebrain areas receiving a 5-HT input, mediate the anticonflict action of tandospirone (a 5-HT1A receptor-related anxiolytics), the behavioral effects of tandospirone were studied in 5,7-dihydroxytryptamine (5,7-DHT) treated rats. By measuring both monoamines and their metabolite levels and densities of [3H]8-OH-DPAT binding in 5,7-DHT-treated rat brain, we confirmed that pretreatment with 5,7-DHT destroyed 5-HT neurons selectively without affecting postsynaptic 5-HT1A receptors located on the postsynaptic neurons. This selective destruction produced no significant changes in the drinking behavior of rats in either punished or unpunished sessions of the Vogel conflict test. Furthermore, this destruction altered neither the effect of tandospirone on punished responding in this procedure nor the potency of tandospirone to induce a flat body posture in rats, which is known as the "serotonin behavioral syndrome". These results suggested that the anticonflict action of tandospirone may be produced, at least in part, by binding to postsynaptic 5-HT1A receptors and activating them as agonists, and not to 5-HT1A autoreceptors located on the cell bodies of 5-HT neurons.