Hiroki Miyate

Simple determination of acetylcholine and choline within 4 min by HPLC-ECD and immobilized enzyme column in mice brain areas

A rapid and simple method using a combination of high-performance liquid chromatography (HPLC) with electrochemical detection (ECD) and an immobilized enzyme column herein is described for simultaneous assay of acetylcholine (ACh) and choline (Ch) in discrete brain areas of the mouse. Perchloric acid extracts of small brain tissues were injected directly onto the HPLC system with no pre-cleanup procedure. The ACh and Ch levels were determined within 4 min for each chromatographic run. Recoveries were 100.0 +/- 4.8% for ACh and 96.1 +/- 1.4% (mean +/- S.D., n = 10) for Ch. Detection limits for both compounds were 0.25 pmol (signal-to-noise ratio of three). The present method has been applied to the measurement of Ch and ACh in several discrete brain areas of the mouse.

Effects of 24-Hr fasting on methamphetamine- and apomorphine-induced locomotor activities, and on monoamine metabolism in mouse corpus striatum and nucleus accumbens

The effects of 24-hr fasting on the vertical (VMA) and horizontal (HMA) locomotor activities, on cage climbing activity and on brain monoamine-related substances, were examined using male ddY mice. Both the VMA and HMA increased with fasting, but not the cage climbing activity. Methamphetamine (2 mg/kg, SC) increased the VMA and HMA in both the feeding and fasting mice, whereas with apomorphine (0.1 mg/kg, SC) both decreased. Furthermore, pretreatment with haloperidol (0.025 mg/kg, SC) showed no influence on the methamphetamine-induced VMA increase in both the feeding and fasting mice. However, pretreatment with haloperidol inhibited the methamphetamine-induced HMA increase in both the feeding and fasting mice and showed a higher level of HMA in fasting mice than in feeding mice. When measuring brain monoamine-related substances, the DA, NE, 5-HT, and 5-HIAA levels in the corpus striatum increased, whereas the 3-MT levels decreased. The monoamine levels in the nucleus accumbens of fasting mice were the same as those in feeding mice, except for a decrease of the 3-MT level. These results suggest that the locomotor activity in fasting mice may be increased by a change in the sensitivity of dopaminergic neurons in the corpus striatum.

Very rapid assay of gamma-aminobutyric acid in mouse brain regions within 3 minutes by high-performance liquid chromatography with electrochemical detection

For assay of gamma-aminobutyric acid (GABA) in brain tissue, a very rapid and simple chromatographic procedure using high-performance liquid chromatography (HPLC) with electrochemical detection (ECD) in combination with precolumn o-phthalaldehyde (OPA) derivatization is described. Perchloric acid extracts of the tissue were mixed with OPA/beta-mercaptoethanol solution and the mixture was injected onto the HPLC system. The present method permits GABA assay within less than 3 min in one chromatographic run. Up to 100 samples a working day can be analyzed in the present method. The present method has been applied to the measurement of GABA levels in discrete brain regions of mice treated with aminooxyacetic acid and isoniazid.

Ultra-rapid assay of brain γ-aminobutyric acid by liquid chromatography with electrochemical detection

We have improved the analysis time and sensitivity of the method for GABA assay by using a very short column (45 mm, 5 μm particle size). The method described here permits GABA assay within 1 min in one chromatographic run

Hyaline Ring Granuloma of the Mandibular Periosteum

Abstract Hyaline ring granuloma (HRG) is a comparatively rare inflammatory condition occurring mainly in the oral region, and is characterized by hyaline rings (HRs) formed in the granulation tissue. This study describes a case of HRG occurring in the mandibular periosteum of an 18-year-old male. Histopathologic, histochemical and electron microscopic studies were performed on surgically excised materials. Histopathologically, ovoid bodies(OBs) surrounded by thin hyaline walls and HRs showing pale-stained eosinophilic thick hyaline walls were both detected. Histochemical study revealed that the OBs contained many granules chiefly composed of starch. Ultrastructurally, the HRs presented a stratiform structure due to the accumulation of cross-banded collagen fibrils with a basement membrane-like lining containing cellulose microfilaments. These results suggest that HRs are formed as follows: the exogenous vegetable materials are encapsulated by collagen, then the component is gradually degraded; the residual cellulose fraction adheres to the inner surface of the collagenous capsules, and the continuous deposition of collagen at the outer surface of the capsules increases its thickness. Finally, thick hyaline walls of HRs are formed. The possible pathogenesis of this curious lesion is discussed for stomatologists.

Effects of caerulein and cholecystokinin-octapeptide on acetylcholine and choline contents in the brains of intact and vagotomized mice.

The effects of caerulein (CLN; 0.5, 5, and 50 micrograms/kg, IP) and cholecystokinin-octapeptide (CCK-8; 5, 50, and 400 micrograms/kg, IP) on the acetylcholine and choline contents in the discrete brain regions were examined, 30, 60, and 120 min after injection into intact and vagotomized mice. In all of the discrete brain regions of the intact mice. CLN and CCK-8 was found to have a complex effect on the acetylcholine and choline contents depending on the brain region, dosage and treatment time. On the other hand, the effect of CLN was abolished completely in the vagotomized mice. Thus, the present study indicates that peripherally administered CLN and CCK-8 have an effect on the central cholinergic system, mainly mediated via the vagus.