Alterations in local cerebral glucose metabolism and endogenous thyrotropin-releasing hormone levels in rolling mouse Nagoya and effect of thyrotropin-releasing hormone tartrate

Ca2+ channels and epilepsy

The epilepsies encompass diverse seizure disorders afflicting as many as 50 million people worldwide. Many forms of epilepsy are intractable to current therapies and there is a pressing need to develop agents and strategies to not only suppress seizures, but also cure epilepsy. Recent insights from molecular genetics and pharmacology now point to an important role for voltage-dependent calcium channels in epilepsy. In this article, I first provide an introduction to the classification of the epilepsies and an overview of neuronal Ca(2+) channels. Next, I attempt to review the evidence for a role of Ca(2+) channels in epilepsy and the insights gained from genetics and pharmacology. Lastly, I describe new avenues for how such information might be exploited in the development of therapeutic reagents.

Sustained release dosage of thyrotropin-releasing hormone improves experimental Japanese encephalitis virus-induced parkinsonism in rats

Thyrotropin-releasing hormone (TRH) has been reported to have some possibilities toward the treatment of affective CNS disorders. However, long term treatments with daily injections are often required. Effects of TRH-SR (sustained release microspheres of TRH) which is encapsulated in copoly (dl-lactic/glycolic acid) using an in-water drying method were investigated in experimental Japanese encephalitis virus (JEV)-induced post-encephalitic parkinsonism rats by a pole test and high performance liquid chromatography (HPLC) with an electrochemical detector (ECD). We have already reported that in adult Fischer rats killed 12 weeks after infection with JEV at the age of 13 days a marked decrease of tyrosine hydroxylase-positive neurons was found in the bilateral substantia nigra. TRH-SR (3 mg/kg per 2 weeks, 4 times injections, subcutaneous [s.c.]) improved bradykinesia observed in the JEV-induced parkinsonism rats. Dopamine (DA) concentrations in the JEV-infected rats were profoundly reduced in the striatum as compared with controls. TRH-SR (3 mg/kg, once, s.c.) increased DA in the striatum 7 days after the injection. Although the pathomechanism of post-encephalitic parkinsonism is different from that of Parkinson's disease and TRH possesses a variety of CNS effects as well, these results suggest that TRH-SR play a possible role in the treatment of Parkinson's disease in addition to post-encephalitic parkinsonism as a supportive drug of L-DOPA.

Effects of thyrotrophin-releasing hormone tartrate and its sustained release formulation on cerebral glucose metabolism in aged rats

The effects of a sustained release formulation of thyrotrophin-releasing hormone (TRH) over two weeks (TRH-SR, 10 or 50 mg kg-1, equivalent to 0.56 or 2.80 mg kg-1 free TRH, respectively) and repeated treatment with TRH tartrate (TRH-T, 0.3, 1.0 or 3.0 mg kg-1, equivalent to 0.2, 0.7 or 2.0 mg kg-1 free TRH, respectively) on the rate of local cerebral glucose utilization (LCGU) were investigated using the quantitative autoradiographic 2-deoxy-[14C]D-glucose method in various brain regions of aged rats. In aged rats (28 months old), the LCGU was significantly reduced as compared with young adult rats (3 months old), while treatment with TRH-SR ameliorated the reduction of the LCGU in a dose-dependent manner. The brain regions ameliorated by TRH-SR were the auditory cortex, septal nucleus, substantia nigra, cerebellar cortex and cerebellar nucleus. In contrast, once-daily repeated treatment over one week with TRH-T at a dose of 0.3 mg kg-1 (equivalent to 50 mg kg-1 of TRH-SR) had no effect on the reduced LCGU in various brain regions in aged rats (27 months old), whereas treatment with a higher dose of TRH-T (0.7 or 2.0 mg kg-1 free TRH) significantly ameliorated the reduction. The comparison of the ameliorating potencies between TRH-T and TRH-SR indicated that TRH-SR had a potency about 7 times greater than TRH-T.

Beneficial effects of TDN-345, a novel Ca2+ antagonist, on ischemic brain injury and cerebral glucose metabolism in experimental animal models with cerebrovascular lesions

The effects of TDN-345 on mortality and ischemic neurological deficit following transient global cerebral ischemia in Mongolian gerbils and also the rate of local cerebral glucose utilization (LCGU) in stroke-prone spontaneously hypertensive rats (SHRSP) with cerebrovascular lesions were investigated. In Mongolian gerbils, ischemia was produced by clamping the bilateral common carotid arteries for 15 min. TDN-345 (0.1-1.0 mg/kg) dose-dependently decreased the mortality and ischemic neurological deficit score when administered orally twice, 60 min before ischemia and 90 min after recirculation. Additionally, TDN-345 (0.2 or 1.0 mg/kg, p.o. once daily for 3 weeks after the onset of stroke) decreased the mortality and recurrence of stroke in SHRSP. To determine the site of action of TDN-345 in the brain, the rate of LCGU in various brain regions in SHRSP with stroke was examined using a [14C]2-deoxy-D-glucose method. The rate of LCGU decreased significantly in all the brain regions in SHRSP with stroke compared with Wistar-Kyoto (WKY) control rats, whereas the reduction in the rate of LCGU in SHRSP with stroke was prevented by TDN-345 treatment, especially in the sensorimotor cortex and locus coeruleus. These results suggest that TDN-345 has therapeutic efficacy in the treatment of cerebrovascular disease.