Differential Contribution of 5-HT, 5-HT, and 5-HT Receptors to Acute Pruriceptive Processing Induced by Chloroquine and Histamine in Mice.

The involvement of serotonin (5-HT) and/or noradrenaline in acute pruriceptive processing in the central nervous system (CNS) has been reported using antidepressants, such as milnacipran, a serotonin and noradrenaline reuptake inhibitor, and mirtazapine, a noradrenergic and specific serotonergic antidepressant; however, the roles of 5-HT receptor family in acute pruriceptive processing have not been fully elucidated in the CNS. In the present study, scratching behavior induced by chloroquine (CQ) was ameliorated by milnacipran or mirtazapine, and these effects were reversed by SB207266, a 5-HT antagonist, or SB258585, a 5-HT antagonist, but not by SB258585, a 5-HT antagonist. Moreover, CQ-induced scratches were mitigated by intrathecal injection of 5-HT agonists, such as BIMU8 and ML10302, and the 5-HT agonist, WAY208466.

Role of kainate receptors in pruriceptive processing in the mouse spinal cord.

Pruritus, including neuropathic and psychogenic pruritus, is an unpleasant feeling that causes a desire to scratch, which negatively impacts physical and psychological aspects of daily life. Nonetheless, little is known about the neural mechanisms involved in pruritus. Glutamate is a predominant excitatory neurotransmitter in the mammalian central nervous system and exerts its effects by binding to various glutamate receptors, including kainate (KA) receptors; however, the precise involvement of each glutamate receptor in pruriceptive processing remains unclear, particularly that of KA receptors.

Roles of 5-HT and 5-HT receptors in acute pruriceptive processing in mice.

The roles of serotonin (5-HT) and/or noradrenaline in acute pruriceptive processing have been demonstrated using antidepressants, such as milnacipran, a serotonin and noradrenaline reuptake inhibitor, and mirtazapine, a noradrenergic and specific serotonergic antidepressant; however, the involvement of 5-HT in acute pruriceptive processing has not yet been elucidated in detail. Scratching events induced by chloroquine (CQ) were attenuated by the administration of milnacipran or mirtazapine, and these effects were reversed by a treatment with ondansetron, a 5-HT antagonist, or SB26970, a 5-HT antagonist. CQ-induced scratching events were also ameliorated by the intrathecal administration of 5-HT, SR572227A and RS56812 (5-HT agonists), and LP211 and LP44 (5-HT agonists), indicating the modulation of CQ-induced scratching events by 5-HT and noradrenaline.

Serotonin and noradrenaline modulate chronic itch processing in mice.

The roles of serotonin and noradrenaline in the modulation of chronic pruriceptive processing currently remain unclear. To clarify the contribution of serotonin and noradrenaline to chronic itch, the effects of the administration of antidepressants or noradrenaline reuptake inhibitors were evaluated in the present study. A pretreatment with milnacipran, a serotonin and noradrenaline reuptake inhibitor, and mirtazapine, a noradrenergic and specific serotonergic antidepressant, attenuated the induction of spontaneous scratching behavior in mice with chronic itch.