Heat production by brown adipocytes of FOK rats genetically resistant to a hot environment

The FOK rat was established as an inbred strain with genotypic adaptation to a hot environment. To investigate the mechanism of the heat resistance of FOK rats, heat production by isolated brown adipocytes in FOK and WKAH rats was measured at 37.0 and 39.9 degrees C. Basal heat production by brown adipocytes of FOK rats was not significantly different from that of WKAH rats. Isoproterenol increased the heat production in a dose-dependent manner in both strains, while 10(-9) M isoproterenol caused a significant increase in WKAH rats and a negligible change in FOK rats. These results indicate that the reason why FOK rats are resistant to the severe heat is partly due to the low heat production by brown adipocytes.

A new method for evaluation of motor deficits in 3-acetylpyridine-treated rats

We established a novel method for quantitative evaluation of the motor deficits induced by 3-acetylpyridine (3-AP) in rats. 3-AP (75 mg/kg, i.p.) was injected in a time-controlled manner by a following injection of niacinamide (NIA; 300 mg/kg, i.p.). Changes in the motor function were evaluated by measuring the maximal height of vertical jump (MHVJ) to escape from an electrical shock on the foot, as well as ataxic gait. The MHVJ decreased and reached a minimum value 5-7 days after the 3-AP treatment. The close correlation of the MHVJ and the incidence of ataxic gait indicates that the decrease of MHVJ is a useful quantitative index of motor deficits.

Increased production of interleukin-10 and inflammatory cytokines in blood monocytes of hemodialysis patients

Chronic hemodialysis (HD) patients have defects in cell-mediated immunity. To investigate the mechanisms underlying this immunodeficiency, we studied the production of cytokines in peripheral blood mononuclear cells (PBMC) from HD patients. PBMC from 22 HD patients and 20 healthy controls were cultured for 48 h in the presence or absence of phytohemagglutinin (PHA), lipopolysaccharide (LPS), or tuberculin purified protein derivative (PPD). Cytokine levels were measured by enzyme-linked immunosorbent assays. Only 64% of HD patients had a positive tuberculin skin test compared to 90% of normal Japanese controls. HD patients showed a diminished proliferative response to PHA. Compared to healthy controls, stimulated PBMC from HD patients produced similar amounts of T cell-derived cytokines (interleukin-2 (IL-2) and interferon-gamma (IFN-gamma)), but greater amounts of monocyte-derived inflammatory cytokines (IL-1 beta, tumor necrosis factor-alpha (TNF-alpha), and IL-8) and a regulatory cytokine (IL-10). IL-10 production was positively correlated with IL-1 beta and TNF-alpha in healthy controls, whereas no correlation was observed in HD patients. Abnormal cytokine production by monocytes may contribute to the immunodeficiency seen in HD patients.

[Synthesis and pharmacological action of TRH analog peptide (Taltirelin)]

Taltirelin hydrate[1-methyl-(S)-4,5-dihydroorotyl-L-histidyl-L-prolineamide tetrahydrate] is a new orally active thyrotropin releasing hormone (TRH) peptide analog synthetized from aspartic acid. From preclinical studies with mice and rats, Taltirelin hydrate was found to be highly stable in the blood and brain as compared with TRH. Furthermore, the CNS stimulating actions of Taltirelin hydrate such as antagonistic actions against pentobarbital-induced anesthesia and reserpine- induced hypothermia were found to be about 100 times stronger and about 8 times longer-lasting as compared with those of TRH. Meanwhile, the affinity of Taltirelin hydrate for TRH-receptors was about 10 times lower, and the endocrine action was about 5 times less potent than those of TRH. Therefore, high CNS-selectivity and long-lasting action of Taltirelin hydrate would be attributed to its high stability in the body and low affinity for TRH-receptors. Oral administrations of Taltirelin hydrate ameliorated consiousness impairment, memory impairment and motor dysfunction in several models. The clinical studies for patients with spinocerebellar degeneration are in progress.

Effect of cyclic polylactates on tumor cells and tumor bearing mice

We studied the effect of cyclic polylactates ranging in size from a degree of polymerization number of 3 to 13 on pyruvate kinase, lactic dehydrogenase, anaerobic glycolysis, growth of tumor cells and survival of tumor bearing mice. Pyruvate kinase and lactic dehydrogenase activities were both inhibited by cyclic polylactates, and the inhibition mechanism of cyclic polylactates on lactic dehydrogenase was noncompetitive. About half the anaerobic glycolytic activity of FM3A ascites tumor cells was inhibited and tumor cell growth was also effectively inhibited by cyclic polylactates. Mice, which were treated with cyclic polylactates after inoculation of FM3A ascites tumor cells lived significantly longer than mice, which were treated with vehicle or non mice.

Mucosal blood flow and generation of superoxide in rat experimental colitis induced by succinic acid

As we consider succinic acid to be an exacerbating factor in ulcerative colitis, we investigated its influence on rat colonic mucosa in terms of mucosal blood flow and superoxide generation. We measured mucosal blood flow by the hydrogen gas clearance method and superoxide generation by the chemiluminescence method, and observed histopathological findings to determine the effects of succinic acid. After the instillation of succinic acid of any concentration tested to the colon, mucosal blood flow decreased. Histopathologically, the higher the concentration of succinic acid, the greater was the erosion formation in the colonic mucosa, while significant polymorpho-nuclear cell infiltration superoxide generation from colon tissue were observed with 0.01% succinic acid compared with higher or lower concentrations. Succinic acid, at fecal concentrations found in active stage ulcerative colitis, appears to be implicated in mucosal injury, mediated by a decrease in colonic mucosal blood flow and infiltration of superoxide-generating polymorpho-nuclear cells into the mucosa.

Leukocytapheresis with leukocyte removal filter as new therapy for ulcerative colitis

Leukocytapheresis (LCAP) with a leukocyte removal filter column was administered for 45 patients with ulcerative colitis (UC). We evaluated changes in the leukocyte count and the differential percentages during LCAP. Cytokine production was assessed from each patient's peripheral mononuclear cells or monocytes. Flow cytometry was performed to assess the removal rates of activated cells and adhesion molecule positive cells by LCAP. Clinical improvement was recognized in 35 of 45 patients during intensive LCAP therapy, and it continued throughout maintenance therapy in 32 patients (71.1%). The leukocyte count was decreased to about 40% during the first 30 min, but it increased to approximately 170% at 20 min after the completion of LCAP. The concentration of tumor necrosis factor (TNF)alpha before LCAP in the effective group was higher than it was in either the ineffective group or the control group. Its level decreased to near normal range after LCAP. In the effective group, the concentrations of interleukin (IL)-1beta, IL-2, interferon (IFN)gamma, and IL-8 were near the normal upper limits before LCAP; however, they had decreased after LCAP. The concentration of IL-4 increased after LCAP. In the ineffective group, in contrast, the concentrations had been at or near normal before the initial LCAP treatment. Flow cytometry study revealed that LCAP could remove the activated cells and adhesion molecule positive cells more effectively. The clinical improvement and the changes observed before and after LCAP therapy suggest that LCAP is able to intervene in the causal mechanism(s) of UC.

Frequent hepatic involvement in adult T cell leukemia: comparison with non-Hodgkin's lymphoma

We examined 111 patients with acute type- or lymphoma type-adult T-cell leukemia (ATL) and compared them with 106 patients with non-Hodgkin's lymphoma (NHL). In addition to skin involvement and hypercalcemia which are already known to be frequent in ATL, ATL patients showed an higher incidence of hepatic involvement. There was more frequent palpable hepatomegaly, higher total bilirubin, GOT, GPT, lactate dehydrogenase (LDH), and alkaline phosphatase values in ATL than in NHL patients (p < 0.0001). Among 36 autopsied liver samples, invasion of ATL cells was confirmed in 22 cases. ATL patients with impaired hepatic function showed shorter survival times than patients without hepatic dysfunction. Moreover, ATL patients showed a worse performance status (PS), a higher incidence of lytic bone lesions, lower total protein (TP) and serum albumin levels than NHL patients. This invasive characters of ATL cells and consequent impaired general condition seemed to be factors affecting the poor prognosis recorded in ATL.

Inhibition of rheumatoid synovial fibroblast proliferation by antisense oligonucleotides targeting proliferating cell nuclear antigen messenger RNA

OBJECTIVE

To evaluate the feasibility of antisense oligonucleotides as therapeutic agents to inhibit synovial cell growth in rheumatoid arthritis (RA).

METHODS

Fibroblast-like cells established from RA synovium were stimulated with interleukin-1beta (IL-1beta) and treated with antisense or sense oligonucleotides targeting proliferating cell nuclear antigen (PCNA) messenger RNA (mRNA). Proliferation of these cells was determined by 3H-thymidine incorporation. Effects of antisense oligonucleotides on the expression of mRNA and protein were evaluated by reverse transcriptase-polymerase chain reaction and immunohistochemical staining, respectively.

RESULTS

Antisense oligonucleotides targeting PCNA inhibited IL-1-stimulated fibroblast proliferation, whereas sense oligonucleotides had no effect. Both mRNA and protein levels of PCNA were suppressed in the cells treated with antisense oligonucleotides, indicating that the antiproliferative effect was occurring through an antisense mechanism.

CONCLUSION

These results suggest that antisense strategies designed to suppress PCNA expression have potential use as therapeutic agents for RA.

The synovial expression and serum levels of interleukin-6, interleukin-11, leukemia inhibitory factor, and oncostatin M in rheumatoid arthritis

OBJECTIVE

To determine the expression of interleukin-6 (IL-6), IL-11, leukemia inhibitory factor (LIF), and oncostatin M (OSM) and their major cellular sources in the joints of rheumatoid arthritis (RA) patients, as well as the correlation of circulating levels of these IL-6-type cytokines and C-reactive protein (CRP).

METHODS

Messenger RNA (mRNA) and protein levels for IL-6, IL-11, LIF, and OSM were determined by using reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively.

RESULTS

Cells isolated from the synovium of RA patients expressed mRNA for IL-6, IL-11, LIF, and OSM at higher levels than did synovial cells from osteoarthritis (OA) patients, and spontaneously released greater quantities of these proteins in culture. Fibroblast cell lines derived from RA synovium were able to produce IL-6, IL-11, and LIF, but not OSM, when stimulated with IL-1 and tumor necrosis factor alpha. OSM was found to be produced spontaneously by synovial tissue macrophages. IL-6, IL-11, LIF, and OSM were present in synovial fluid from the RA patients; levels of IL-6, LIF, and OSM were present in significantly greater quantities in RA patients than in OA patients. However, only IL-6 was significantly elevated in the serum of RA patients and correlated with the serum CRP level, while other IL-6-type cytokines were not detected.

CONCLUSION

IL-6, IL-11, LIF, and OSM are all produced in large amounts at the site of disease activity, but IL-6 derived from synovial fibroblasts may be the major hormone-like mediator that induces the hepatic synthesis of acute-phase proteins in RA.

Construction of a starch-utilizing yeast by cell surface engineering

We have engineered the cell surface of the yeast Saccharomyces cerevisiae by anchoring active glucoamylase protein on the cell wall, and we have endowed the yeast cells with the ability to utilize starch directly as the sole carbon source. The gene encoding Rhizopus oryzae glucoamylase with its secretion signal peptide was fused with the gene encoding the C-terminal half (320 amino acid residues from the C terminus) of yeast alpha-agglutinin, a protein involved in mating and covalently anchored to the cell wall. The constructed plasmid containing this fusion gene was introduced into S. cerevisiae and expressed under the control of the glyceraldehyde-3-phosphate dehydrogenase promoter from S. cerevisiae. The glucoamylase activity as not detected in the culture medium, but it was detected in the cell pellet fraction. The glucoamylase protein transferred to the soluble fraction from the cell wall fraction after glucanase treatment but not after sodium dodecyl sulfate treatment, indicating the covalent binding of the fusion protein to the cell wall. Display of the fused protein was further confirmed by immunofluorescence microscopy and immunoelectron microscopy. The transformant cells could surely grow on starch as the sole carbon source. These results showed that the glucoamylase was anchored on the cell wall and displayed as its active form. This is the first example of an application of cell surface engineering to utilize and improve the metabolic ability of cells.

[Leukocytapheresis for ulcerative colitis]

Major inclusion criteria for leukocytapheresis (LCAP) therapy were mainly insufficient response to conventional drugs therapy. LCAP was administered once a week for 5 weeks of intensive therapy and once approximately a month for maintenance therapy, for 38 patients with UC. LCAP could remove approximately 1 x 10(10) white blood cells in each session. In the evaluation, we classified the response to the LCAP as: 1) excellent, 2) moderately improved, 3) no change, and 4) deterioration. Clinical improvement was recognized in 29 of 38 patients (76%) including 8 with dramatic response during the intensive therapy, and continued throughout the maintenance therapy in 26 patients (68.4%). Even though their symptoms were mild, the patients with more than 5 years UC history seemed to be not effective. The patients with moderately improvement and with excellent response have kept remission for about 20 months and about 2.5 years on an average, respectively. Clinical and blood examinations showed no side effects in any cases. It suggests that LCAP is able to be a UC treatment between drug therapies and an operation.

[Remission by leukocytapheresis for a patient with ulcerative colitis found refractory by conventional drug therapies]

A 40-year-old male was admitted to our hospital on August 30, 1994 to receive a new ulcerative colitis (UC) therapy, leukocytapheresis (LCAP). On the admission day, he had bloody stool 5 to 6 times/day, abdominal pain, slight fever, and hypoproteinemia. His UC type was moderately severe left-sided colitis with pseudopolyposis. Prior to admission to our hospital, his condition had not improved for about 9 months, despite drug therapies such as salicylazosulphapyridine, intravenous high dose prednisolone, protease inhibitor, intraarterial hydrocortisone sodium succinate, 4 series of pulse therapies with metylpredonisolone, enema of corticosteroid, azathioprine (Imuran), and cyclosporine at another hospital. Thus he was introduced to our college hospital and treated by LCAP since September 1. After 10 LCAP sessions, remission was observed and the patient discharged on December 23. Until he was later operated on for heavy bleeding after he had discontinued treatment and had drunk heavily, he had maintained remission for 13 months with LCAP only once a month even after we gradually decreased the other medical supports and stopped all of them. After LCAP, the normalization of high percentage of leukocytes presented HLADR+ and lymphocytes presented CD 11 a+ CD 8+ was also observed. This suggests LCAP intercepts the excess immune reaction in UC by removing leukocytes.

Glucose metabolism and protective biochemical mechanisms in a rat brain affected by kaolin-induced hydrocephalus

To clarify glucose metabolism in a hydrocephalic rat brain, substances related to glycolytic metabolism were biochemically measured. Kaolin-induced hydrocephalic rats were sacrificed and lactate dehydrogenase (LDH), LDH isozyme, lactate, adenosine triphosphate (ATP), and isocitrate dehydrogenase (ICDH) were measured in the following regions: cortex, thalamus, midbrain, hippocampus, cerebellum, and pons with medulla. During the development of hydrocephalus, lactate and LDH increased in most regions, the LDH M-subunit increased in the cortex, and ICDH decreased in most regions. However, ATP levels did not change. The increases in lactate, LDH and M-subunit suggested an anaerobic environment in the cell leading to activation of the anaerobic glycolysis. The decrease in ICDH represented a diminution of the tricarboxylic acid cycle. Through these alterations, the ATP level can be kept constant during the course of hydrocephalus, allowing the brain to create a better biochemical milieu.

Suppression of neointimal thickening by a newly developed HMG-CoA reductase inhibitor, BAYw6228, and its inhibitory effect on vascular smooth muscle cell growth

1. The aim of this study was to determine whether BAYw6228 (BAYw), a newly developed 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitor, could suppress an atherogenic process such as intimal thickening by a mechanism other than lowering the level of serum cholesterol. 2. First, we evaluated the in vitro effect of BAYw on the proliferation of vascular smooth muscle cells (SMC) from various species: Sprague-Dawley (SD) rats. New Zealand (NZ) white rabbits, intimal cells from Watanabe hereditary hyperlipidemic (WHHL) rabbit and SMC from the new-born human aorta. The increasing rate of total protein content of these cells was inhibited by the addition of BAYw in a dose-dependent fashion. In the presence of 2% foetal calf serum (FCS), the value of IC50 was 1.0 microM in SD rats, 2.1 microM in NZ white rabbits, and 0.3 microM in WHHL rabbits. With human SMC, the value was 0.02 microM in the presence of 10% FCS and 0.2 microM with a mixture of growth factors. 3. Based on these above in vitro findings, we next examined the in vivo effect of the agent to determine whether it could suppress rabbit intimal thickening induced by balloon catheterization. A balloon catheter was inserted from a peripheral branch of the left external carotid artery to the aorta to denude the endothelium of the left common carotid artery in Japanese white rabbits. After 12 days they were divided into control and BAYw groups. The former were subcutaneously injected with saline and the latter with BAYw 1 mg kg-1 day-1. Two days after the beginning of treatment, a second balloon injury was performed to the previously injured left common carotid artery in both groups. After another two weeks, the left common carotid artery was removed and variously stained. Although the total serum cholesterol in the BAYw group was significantly lower than in the control (P < 0.05), the difference was not enough to affect intimal thickening. In addition, the BAYw group had a smaller intima/media ratio than the control group, decreasing to 45% of control (P < 0.05). By anti-alpha smooth muscle actin antibody staining, these intimal thickening areas were entirely occupied by SMCs, and their amount was attenuated by BAYw. By anti-rabbit macrophage antibody (RAM 11) staining, the number of positive cells in the intimal thickening was markedly decreased in the BAYw group compared to control (P < 0.01). 4. These results indicate that BAYw has an inhibitory effect on intimal thickening by attenuating intimal SMC proliferation and infiltration of macrophages, suggesting that BAYw could be effective in the prevention of the progression of atherosclerotic plaque-like restenosis after angioplasty.

Depolymerized holothurian glycosaminoglycan (DHG) prevents neointimal formation in balloon-injured rat carotid artery

The in vivo activity of depolymerized holothurian glycosaminoglycan (DHG), a newly developed polysaccharide anticoagulant, on neointimal formation induced by a balloon catheter in the left common carotid artery of rats was investigated. In every Sprague-Dawley rat weighing approximately 400 g, a Forgaty 2Fr balloon catheter was inserted from the left femoral artery to the left common carotid artery, and was passed through three times in order to denude the endothelium of the artery. These rats were divided into four groups by the following treatment protocols; DHG was given to rats by daily subcutaneous injection into their abdomens at a dose of 3 mg/kg or 10 mg/kg (D3 or D10 group). For controls, 250 microl saline was injected daily (C group). Furthermore, 1 mg/kg of unfractionated heparin was also injected daily as a comparison to DHG (H group). Each treatment was performed in six rats, and the injections were continued for two weeks after the catheterization. The area ratio of thickened intima/media (I/M ratio) treated with DHG decreased in a dose-dependent manner compared to the control. In addition, the ratio in the D10 group was significantly lower than in the control (P < 0.01). However, the ratio in the H group did not decrease. By anti-a smooth muscle actin antibody staining the intimal thickening layers were seen to be completely occupied by proliferated smooth muscle cells, and their amount in these layers was attenuated by the DHG treatment. This indicated that DHG has an inhibitory effect on intimal thickening induced by balloon catheterization, and that this might be due to the inactivation of aberrant smooth muscle cells by this agent.

BAYw6228 suppresses accumulation of macrophages in balloon-induced intimal thickening of rabbit carotid artery

To determine the in vivo activity of BAYw6228 (BAYw), a newly developed 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitor, we examined its effect on balloon catheterization-induced carotid arterial intimal thickening in Japanese white rabbits. In all rabbits weighing approximately 3.5 kg, a balloon catheter was inserted from a peripheral branch of the left external carotid artery to the aorta in order to denude the endothelium of the left common carotid artery. At day 12, they were divided into control and BAYw groups. The latter were subcutaneously injected with BAYw, 1 mg/kg/day, for the following 17 days. At day 15, the second balloon catheterization was performed in the same left common carotid artery in both groups. After another two weeks, the left common carotid artery was removed and stained with Elastica-Masson (EM) and anti-rabbit macrophage antibody (RAM 11). With RAM 11 staining, the number of positive cells in the intimal thickening was markedly decreased in the BAYw group compared with the control group (P < 0.01). Compared with the area ratio of the thickened intima/media layer of the control group, that of the BAYw group was significantly decreased to 45% (P < 0.05). These results indicate that BAYw prevents accumulation of macrophages and consequently contributes to the inhibition of intimal thickening induced by balloon catheterization.

Integration patterns of HTLV-I provirus in relation to the clinical course of ATL: frequent clonal change at crisis from indolent disease

We examined human T-lymphotropic virus type I (HTLV-I) DNA integration in 68 patients with adult T-cell leukemia/ lymphoma (ATL) by Southern blotting using EcoRI, which does not cut within the 9 kb of the genome and probes for pX and gag-pol region of HTLV-I. We detected defective proviral integration as a monoclonal band of various sizes with the pX but not with the gag-pol probe, or a monoclonal band of less than 9 kb with the pX probe, in 20 patients (29.4%). These were designated defective (D) type. With both probes, a single band greater than 9 kb was detected in 34 (50.0%), designated complete (C) type, and two or more bands greater than 9 kb, were designated multiple (M) type, in 14 (20.6%). Advanced age, a high LDH value, and hypercalcemia were more frequent in D type patients. The median survival time (MST) was 6.8, 24.4, and 33.3 months, for D, C, and M types, respectively (log rank P = .006). Among 52 sequentially examined patients, the HTLV-I integration patterns changed in 4 (7.5%). In three of these four, the rearrangements of the T-cell receptor (TCR)b gene concomitantly changed, suggesting the appearance of a new ATL clone. Another patient had the same rearrangement of the TCRb gene, indicating clonal evolution. The HTLV-I integration pattern changed at crisis from indolent to aggressive ATL in three patients. These findings suggested that the HTLV-I integration patterns have clinical implications in ATL pathophysiology. In contrast to the clonal evolution characteristic of the multistep carcinogenesis of most human malignancies, the frequent clonal change of ATL at crisis is a peculiar phenomenon, probably reflecting the emergence of multiple premalignant clones in viral leukemogenesis as suggested in Epstein-Barr virus associated lymphomagenesis in the immunocompromised host.

Detection of herpes simplex DNA in semen and menstrual blood of individuals attending an infertility clinic

OBJECTIVE

To determine a possible link between herpes simplex virus 1 (HSV) and infertility.

METHOD

A specifically designed polymerase chain reaction with nested primers, was developed and used to test for HSV in 153 men and 20 women attending an infertility clinic.

RESULTS

HSV DNA was detected in 37 (24%) out of 153 semen samples and in 11 (55%) out of 20 menstrual blood samples. However, HSV DNA (0%) was not detected in the semen of 16 males with children. A significant association between the evidence for infertility and an HSV positive test was observed in men (Fisher's exact test, p = 0.024), and a stronger effect was found in females after failed in vitro fertilization (Fisher's exact test p = 0.0086).

CONCLUSION

This is the first report of the detection of herpes simplex virus DNA in semen and menstrual blood. Encouraging preliminary results justify antiviral therapy in case of a positive test.

Comparative analysis of CD45RA- and CD45RO-positive CD4+T cells in peripheral blood, synovial fluid, and synovial tissue in patients with rheumatoid arthritis and osteoarthritis

To determine whether the predominant infiltration with memory CD4+T cells in joints is specific to the local immune and inflammatory response in rheumatoid arthritis (RA), the proportions of CD45RA+ or CD45RO+ cells in the CD4+T cell populations in three different compartments (i.e., peripheral blood, synovial fluid, and synovial tissue) from patients with RA and osteoarthritis (OA) were compared by two-color flow-cytometric analysis. In the CD4+T cell population of peripheral blood, the number of CD45RO+ cells was relatively higher than CD45RA+ cells in both RA and OA patients, but their percentages did not differ from those found in healthy individuals. However, the great majority of CD4+T cells present in synovial fluid and synovial tissue were CD45RO-positive and CD45RA-negative in both patient groups; although CD4+T cells infiltrating both the disease compartments were markedly greater in RA joints, their mean percentages of CD45RO+ cells were not significantly different from those in OA joints. These data indicate that an accumulation of CD45RO+ memory CD4+T cells is a generalized phenomenon during local inflammatory responses in both RA and OA joints, and may be due mainly to the propensity of these cells to preferentially transmigrate into the inflamed joint via adhesion molecules as compared with CD45RA+ naive CD4+T cells.

Distribution of thyrotropin-releasing hormone (TRH) receptors in the brain of the ataxic mutant mouse, rolling mouse Nagoya

Thyrotropin-releasing hormone (TRH) and its analog, TA-0910, ameliorate the ataxia of the mutant mouse, rolling mouse Nagoya, by metabolic normalization in the ventral tegmental field (VTF). We here investigated the distribution of cerebral TRH receptors in the rolling mouse to clarify the sites of action of these drugs. TRH receptors were widely distributed in multiple brain areas, including in the VTF and the cuneiform nucleus (CnF) which terminates in the VTF. These results suggest that TRH and TA-0910 directly activate the VTF by acting on TRH receptors in the VTF and indirectly activate it through the receptors in the CnF.

Chronic anti-ataxic actions of the novel thyrotropin-releasing hormone (TRH) analog, TA-0910, during and after repeated administration in Rolling mouse Nagoya: behavioral and pharmacokinetic studies

Anti-ataxic effects of TA-0910, a novel thyrotropin-releasing hormone analog, in mice of the ataxic mutant mouse strain Rolling mouse Nagoya (RMN) are sustained beyond its 2-week oral administration period (Kinoshita et al., Eur. J. Pharmacol., 274, 65-72, 1995). We examined the concentration of TA-0910 in the central nervous system (CNS) of RMN after repeated administration in an attempt to clarify the mechanism of the sustained effect of the drug. Repeated administration of TA-0910 (3 mg/kg/d, i.p.) for 2 weeks produced a long-lasting ameliorating effect on ataxia in RMN, and this effect was maintained until 3 weeks after drug withdrawal. The concentrations of TA-0910 in the cerebrum and brain stem 24 h after the final administration were twice the concentration observed 24h after single administration. The cerebellum cencentration of TA-0910 was more than 4 times that observed 24 h after final administration. After repeated administrations, the drug concentrations in the brain tissues gradually decreased, but the drug was still detectable in the cerebrum and brain stem 3 weeks after withdrawal. However, these concentrations of TA-0910 3 weeks after withdrawal were as low those observed 24 h after single administration when there were no anti-ataxic effects. These observations suggest that the long-lasting ameliorating effect on the ataxia during and after repeated administration of TA-0910 is not ascribable to the drug remaining in the CNS of RMN.