Region-specific elevation of D₁ receptor-mediated neurotransmission in the nucleus accumbens of SHR, a rat model of attention deficit/hyperactivity disorder.

Spontaneously hypertensive rats (SHR) are widely used as a rat model of attention deficit/hyperactivity disorder (AD/HD). Here, we conducted neurochemical and behavioral studies in SHR to clarify the topographical alterations in neurotransmissions linked to their behavioral abnormalities. In the open-field test, juvenile SHR showed a significant hyperactivity in ambulation and rearing as compared with Wistar Kyoto rats (WKY).

Modulation of antipsychotic-induced extrapyramidal side effects by medications for mood disorders.

Antipsychotic drugs are widely used not only for schizophrenia, but also for mood disorders such as bipolar disorder and depression. To evaluate the interactions between antipsychotics and drugs for mood disorders in modulating extrapyramidal side effects (EPS), we examined the effects of antidepressants and mood-stabilizing drugs on haloperidol (HAL)-induced bradykinesia and catalepsy in mice and rats. The selective serotonin reuptake inhibitors (SSRIs), fluoxetine and paroxetine, and the tricyclic antidepressant (TCA) clomipramine, which showed no EPS by themselves, significantly potentiated HAL-induced bradykinesia and catalepsy in a dose-dependent manner.

Serotonergic modulation of extrapyramidal motor disorders in mice and rats: role of striatal 5-HT3 and 5-HT6 receptors.

Previous studies showed that 5-HT(1A) and 5-HT(2) receptors play an important role in controlling the extrapyramidal motor disorders. However, the functions of other 5-HT receptor subtypes remain elusive. To elucidate the role of 5-HT receptors, specifically of 5-HT(3) ∼5-HT(7) subtypes, in modifying antipsychotic- induced extrapyramidal side effects (EPS), we studied the effects of the 5-HT stimulant 5-hydroxytryptophan (5-HTP) and various 5-HT receptor antagonists on haloperidol (HAL)-induced bradykinesia and catalepsy in mice and rats.

Atypical antipsychotic properties of blonanserin, a novel dopamine D2 and 5-HT2A antagonist.

Blonanserin is a novel antipsychotic agent that preferentially interacts with dopamine D(2) and 5-HT(2A) receptors. To assess the atypical properties of blonanserin, we evaluated its propensity to induce extrapyramidal side effects (EPS) and to enhance forebrain Fos expression in mice. The actions of AD-6048, a primary metabolite of blonanserin, in modulating haloperidol-induced EPS were also examined.

Role of cortical and striatal 5-HT1A receptors in alleviating antipsychotic-induced extrapyramidal disorders.

Previous studies have revealed that 5-HT(1A) agonists ameliorate antipsychotic-induced extrapyramidal symptoms (EPS) through postsynaptic 5-HT(1A) receptors. Here, we conducted an intracerebral microinjection study of (+/-)-8-hydroxy-2-(di-n-propylamino)-tetralin ((+/-)8-OH-DPAT) to determine the action site of the 5-HT(1A) agonist in alleviating EPS. Bilateral microinjection of(+/-)8-OH-DPAT (5 microg/1microL per side) either into the primary motor cortex (MC) or the dorsolateral striatum (dlST) significantly attenuated haloperidol-induced catalepsy in rats.

Therapeutic potential of alpha2 adrenoceptor antagonism for antipsychotic-induced extrapyramidal motor disorders.

We examined the effects of JP-1302 (a selective alpha2C antagonist), BRL-44408 (a selective alpha2A antagonist) and yohimbine (a non-selective alpha2 antagonist) on haloperidol-induced bradykinesia and catalepsy in mice to elucidate the role of alpha2 adrenoceptor subtypes in modifying extrapyramidal motor disorders. JP-1302 (0.1-1 mg/kg, s.

Effects of tandospirone, a 5-HT1A agonistic anxiolytic agent, on haloperidol-induced catalepsy and forebrain Fos expression in mice.

We studied the effects of tandospirone, a 5-HT(1A) agonistic anxiolytic agent, on haloperidol-induced catalepsy and forebrain Fos expression in mice. Haloperidol (0.5 mg/kg, i.

Anticataleptic 8-OH-DPAT preferentially counteracts with haloperidol-induced Fos expression in the dorsolateral striatum and the core region of the nucleus accumbens.

We studied the effects of the 5-HT(1A/7) agonist 8-OH-DPAT on haloperidol-induced catalepsy and forebrain Fos expression in mice to clarify its mechanism in modulating extrapyramidal motor disorders. 8-OH-DPAT (0.1-1mg/kg, i.

Evaluation of the antibradykinetic actions of 5-HT1A agonists using the mouse pole test.

To clarify the role and mechanism of the 5-HT1A receptor in modulating extrapyramidal motor disorders, we studied the actions of 5-HT1A agonists in the mouse pole test, a valid model of parkinsonian bradykinesia. Haloperidol markedly delayed pole-descending behavior of mice in the pole test, and this effect was alleviated by the antiparkinsonian agent trihexyphenidyl (a muscarinic antagonist). The selective 5-HT1A agonists, 8-hydroxydipropylaminotetraline (8-OH-DPAT) and tandospirone, significantly attenuated haloperidol-induced bradykinesia in a dose-dependent manner.