Effects of mirogabalin, a novel ligand for the α2δ subunit of voltage-gated calcium channels, on N-type calcium channel currents of rat dorsal root ganglion culture neurons.

Mirogabalin, which is a novel ligand for the α2δ subunit of voltage-gated calcium channels, is being developed for treating neuropathic pain including diabetic peripheral neuropathy and postherpetic neuralgia. Mirogabalin possesses unique α2δ subunit binding characteristics and has potent and long-lasting analgesic effects in neuropathic pain models. In the present study, we investigated the effects of mirogabalin on N-type calcium channel currents of the rat dorsal root ganglion (DRG) culture neurons using the whole-cell patch clamp technique. Small or medium DRG neurons were isolated from Sprague-Dawley rats and were incubated for 20 to 24 h with mirogabalin or pregabalin. The DRG neurons were depolarised from a holding potential of -40 mV to +40 mV in steps of 10 mV for 220 ms, and elicited N-type calcium channel currents were recorded. The N-type calcium channel currents were verified by sensitivity to ω-conotoxin GVIA, a selective N-type calcium channel blocker. Mirogabalin inhibited the calcium channel currents of rat DRG neurons at 50 µM, and pregabalin inhibited them at 200 µM. Mirogabalin and pregabalin showed significant differences in the peak current densities at depolarisation to -20 and -10 mV when compared with that shown by the vehicle control. In conclusion, mirogabalin inhibits N-type calcium channel currents in rat DRG culture neurons. The potent and long-lasting analgesic effects of mirogabalin are thought to be associated with its potent and selective binding to α2δ-1 subunits and following functional inhibition of calcium channel currents.

Analgesic effects of the novel α2δ ligand mirogabalin in a rat model of spinal cord injury.

Mirogabalin, which is a novel ligand for the α2δ subunit of voltage-gated calcium channels, is under development for the treatment of pain associated with diabetic peripheral neuropathy and postherpetic neuralgia. Mirogabalin possesses unique binding characteristics to α2δ subunits and potent and long-lasting analgesic effects in peripheral neuropathic pain models. In the present study, we investigated the analgesic effects of mirogabalin in a rat model of spinal cord injury as an experimental animal model for central neuropathic pain. The spinal cord injury model was established by acute compression of the spinal cord at the T6/7 level with a microvascular clip in male rats. Twenty-eight days after spinal cord injury, the animals received the test compound orally, and the paw withdrawal threshold to mechanical stimulation was determined using the von Frey test at 0 (before administration), 2, 4, 6, 8, and 24 h after administration. The area under the curve of the paw withdrawal threshold (paw withdrawal threshold AUC) was also calculated. In rats subjected to spinal cord injury, mechanical allodynia was demonstrated by a decreased paw withdrawal threshold. A single oral administration of mirogabalin (2.5, 5, or 10 mg/kg) significantly increased the paw withdrawal threshold. The effects of mirogabalin were still significant 6 or 8 h after administration. The paw withdrawal threshold AUC was significantly higher in the treated animals than in the control group. In conclusion, mirogabalin showed potent and long-lasting analgesic effects in a rat model of spinal cord injury and may therefore provide effective pain relief for patients with central neuropathic pain.

[Two types of depersonalization--reconsideration from a descriptive-phenomenological view point].

The term depersonalization has been vaguely used in clinical contexts and there is confusion over its nosological positioning. Although the syndrome has been assigned a niche of its own in the European psychiatric taxonomy, the American's Diagnostic and Statistical Manual of Mental Disorders (DSM-III, IV) labeled it under the term Dissociative Disorder. The latter, which does not agree with the classical theory of Janet, seems to have no basis on traditional psychopathology and is not derived from any dissociative theories. In this paper the descriptive characteristics of depersonalization are discussed with regard to the features of "observing self" and the relationship between experiences and selves, according to which the authors distinguish two types of depersonalization: an "excessive-self-reflecting type" and an "absorbed-in-experience type". Whereas the former coinsides with the typical depersonalization neurosis, in which excessive self-reflection plays an important role in reducing the sense of reality, in the latter over-absorption in some situations leads the patient to construct a wall to block out reality. We suggest that in making a distinction between these two types, the psychopathology of depersonalization will be better clarified.

A clinical study on suicide among schizophrenics.

We conducted a clinical investigation of 80 suicides who met the DSM-III-R criteria for schizophrenia. The results using this approach showed no significant difference with those of preceding studies, and general features regarding the phenomenology of suicide among schizophrenics worldwide were recognized. The present study, however, served to underscore the following points: (i) suicide of schizophrenics must be considered a concern at all stages of the disease; (ii) the subjective strength of the will to die may be more important for the committing suicides than the lethality of the methods employed; and (iii) a change in the environment, for example, a hospital admission or discharge, may trigger suicide. A control group of 80 living schizophrenics with no past attempted suicide was then matched to the suicide group with respect to sex and illness duration, in order to identify the predictors of suicide. In a logistic regression analysis, the presence of suicidal ideation, degree of anxiety estimated by positive and negative syndrome scale, and birth order were revealed as predictors of suicide. As to the birth order, the risk is higher in middle children.