Biomedical subjects

I Ishikawa

Publications and source records attributed to I Ishikawa.

At least 37 records · Page 2Linked to original sources

PubMed2002

Effects of interleukin-4 on proteoglycan accumulation in human gingival fibroblasts.

In inflammatory gingival diseases, cytokines have been demonstrated to play critical roles by coordinating the stimulation of immunological and connective tissue cells. The activities of these cells, degrading and remodeling extracellular matrices, constitute the major pathological and repair processes. Thus, elucidating cellular and molecular events occurring in inflamed connective tissues is crucial for the understanding and treatment of inflammation. In order to test a hypothesis that proinflammatory cytokines affect metabolism of major extracellular matrix molecules, we studied metabolism of proteoglycans (PGs) by human gingival fibroblasts (HGF) under the influence of interleukin-4 (IL-4) as a model of gingivitis. HGF in cell culture were metabolically radiolabeled using [3H]glucosamine and [35S]sulfate in the presence or absence of IL-4, and the labeled PGs were analyzed by chromatographic techniques. The incorporation of 35S into PGs increased with IL-4 both in media and cell layer. At 100 ng/ml of IL-4, the increment of 35S incorporation over control culture was 16-39% (p<0.001) in media and 12-35% (p=0.01) in cell layer. The 35S-labeled macromolecules were PGs containing heparan sulfate (HS) and chondroitin sulfate (CS) chains. From the molecular weight and glycosaminoglycan composition analyses, versican and perlecan-type and biglycan and decorin-type were very likely to be the major PG constituents both in media and cell layer. IL-4 stimulated synthesis of versican and perlecan-type more potently than biglycan and decorin-type. With IL-4 treatment, the ratio of CSPG/HSPG decreased in media and increased in cell layer. This ratio suggested that syndecan family HSPGs were also present in HGF. In conclusion, IL-4 stimulated accumulation of CS/HSPGs in human gingival fibroblasts.

Adult↗

PubMed2002

Compositional analysis of root cementum and dentin after Er:YAG laser irradiation compared with CO2 lased and intact roots using Fourier transformed infrared spectroscopy.

The present study examines the dental root after Er:YAG laser irradiation, compared with CO2 lased and non-treated surfaces, using Fourier Transformed Infrared (FTIR) spectroscopy. Freshly extracted human teeth were irradiated by Er:YAG laser at an energy output of 40 mJ/pulse, 10 Hz (0.4 watts), with or without water coolant, and by CO2 laser at an energy output of 0.5 watts in continuous wave mode without coolant. The surfaces were chalky and smooth after irradiation by Er:YAG laser with water coolant, were charred and irregular after irradiation by Er:YAG laser without water coolant, and were completely carbonized after CO2 laser irradiation. The FTIR profiles from samples of the surfaces that were irradiated by Er:YAG laser with water coolant were similar to those from non-treated samples, except for a slight decrease on the OH and amide bands, which are mainly related to organic components. This decrease was observed to be extreme after CO2 laser irradiation and moderate after Er:YAG laser irradiation without coolant. The formation of new bands showing toxic substances was observed to a large extent after CO2 laser irradiation and to a smaller extent after Er:YAG laser irradiation without water coolant. In contrast, no such bands were detected after Er:YAG laser irradiation with water coolant. The present results show that these laser treatments selectively ablated more organic components than inorganic components and that Er:YAG laser irradiation with water coolant did not cause major compositional changes or chemically deleterious changes in either root cementum or dentin.

Aluminum Silicates↗

PubMed2002

LPS-stimulated human gingival fibroblasts inhibit the differentiation of monocytes into osteoclasts through the production of osteoprotegerin.

Periodontitis is an inflammatory bone disease caused by Gram-negative anaerobic bacteria, but the precise mechanism of bone destruction remains unknown. Activated T lymphocytes secrete receptor activator of NF-kappaB ligand (RANKL) and support the differentiation of monocytes into mature osteoclasts. The purpose of this study was to examine the expression of RANKL and its inhibitor, osteoprotegerin (OPG), in inflamed gingival tissue and to clarify the role of human gingival fibroblasts (HGFs) in osteoclastogenesis regulated by RANKL. HGFs and gingival mononuclear cells (GMCs) were obtained from chronic periodontitis patients during routine periodontal surgery. Expression of OPG and RANKL mRNA in gingival tissue and HGFs was examined with RT-PCR. OPG production was measured using ELISA. Expression of RANKL, CD4, CD8 and CD69 on GMCs was determined by flow-cytometry using RANK-Fc fusion protein and the respective monoclonal antibodies. Osteoclastogenesis by RANKL was assayed by counting the number of tartarate-resistant acid phosphatase (TRAP)-positive cells after culturing human peripheral blood monocytes with recombinant human RANKL and macrophage-colony stimulating factor (M-CSF) for 10 days. OPG and RANKL mRNA were expressed in 80% (16/20) and 25% (5/20) of periodontitis lesions, respectively. OPG, but not RANKL, mRNA was expressed within HGFs. OPG mRNA expression and production by HGFs was augmented by LPS stimulation. All GMC samples expressed CD69, and two of five GMC samples expressed RANKL. The culture supernatant of LPS-stimulated gingival fibroblasts significantly reduced the number of TRAP positive cells generated by culturing monocytes with RANKL and M-CSF. The present study suggests that LPS-stimulated HGFs inhibit monocyte differentiation into osteoclasts through the production of OPG.

Antigens, CD↗

PubMed2002

Noggin blocks osteoinductive activity of porcine enamel extracts.

Enamel extracts induce biomineralization such as osteogenesis and cementogenesis, but the molecular component responsible for this activity remains uncertain. We fractionated enamel extracts from developing pig teeth and isolated the osteoinductive fraction. Proteins from pig enamel scrapings were extracted under alkaline conditions (pH 10.8) and fractionated with the use of a Sephadex G-100 (size exclusion) column. The ability of each fraction to enhance alkaline phosphatase (ALP) activity was assayed in ST2 cells, a mouse bone marrow stromal cell line. The osteoinductive fraction of enamel extracts (OFE) was found in fractions 44 and 45, which induced ST2 cells to express the phenotype of bone-forming osteoblasts, and to form mineralized nodules. Furthermore, the ALP activity of ST2 cells exposed to OFE was reduced by noggin, an antagonist of BMPs, and OFE reacted with BMP-2/4 antibody in dot-blot analysis. These results indicate that OFE contains BMPs that contribute to the induction of biomineralization.

Alkaline Phosphatase↗

PubMed2001

Clonal evolution from trisomy into tetrasomy of chromosome 8 associated with the development of acute myeloid leukemia from myelodysplastic syndrome.

Tetrasomy 8, though rare, is usually associated with trisomy 8, a far more common chromosomal abnormality in acute myeloid leukemia (AML). Yet the clonal relationship between trisomy 8 and tetrasomy 8 in the cases with these chromosomal abnormalities has been unclear. Here, we report a case of a 17-year-old male, diagnosed as having a myelodysplastic syndrome (MDS). Chromosome analysis showed the presence of trisomy 8. Five years later, he developed overt AML exhibiting tetrasomy 8 only. After chemotherapy, the blast cells in the bone marrow decreased to 3.4%, and the karyotype showed trisomy 8 alone. Fluorescence in situ hybridization using a probe specific for chromosome 8 showed that the percentages of cells exhibiting 2/ 3 /4 signals were 7.8/89.2/2.0 at the MDS stage, 20.5/36.1/41.0 when overt AML developed and 24.0/72.1/2.4 after chemotherapy. These results suggested that tetrasomy 8 is derived from the AML clone, possibly evolved from the MDS clone with trisomy 8. To our knowledge, this is the first detailed case report of clonal evolution from trisomy 8 into tetrasomy 8 associated with the development of AML from MDS.

Adolescent↗

PubMed2001

Downregulation of lipopolysaccharide-induced intercellular adhesion molecule-1 expression via EP2/EP4 receptors by prostaglandin E2 in human fibroblasts.

In the present study, the effect of prostaglandin E2 (PGE2) on intercellular adhesion molecule-1 (ICAM-1) expression in human gingival fibroblasts (HGF) stimulated with lipopolysaccharides (LPS) was investigated. LPS were isolated from periodontopathic bacteria, Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) and Porphyromonas gingivalis (P. gingivalis), by the phenol-water method and Escherichia coli (E. coli) LPS was used as a control. PGE2 significantly inhibited A. actinomycetemcomitans-, P. gingivalis- and E. coli-LPS-induced ICAM-1 expression. Next, of four PGE2 receptor subtypes (EP1, EP2, EP3 and EP4), we examined which subtype(s) was involved in inhibition of LPS-elicited ICAM-1 expression by PGE2. Eleven-deoxy-PGE1, a selective EP2/EP4 agonist, and butaprost, a selective EP2 agonist, attenuated A. actinomycetemcomitans-, P. gingivalis- and E. coli-LPS-elicited ICAM-1 expression, although butaprost was less potent than PGE2 and 11-deoxy-PGE1. Sulprostone, an EP1/EP3 agonist, and ONO-AP-324, an EP3 agonist, was inert to the LPS-elicited ICAM-1 expression. Furthermore, dibutyryl cAMP, a cAMP analogue, and forskolin, an adenylate cyclase activator, downregulated A. actinomycetemcomitans-, P. gingivalis- and E. coli-LPS-elicited ICAM-1 expression in HGF. Our data suggest that PGE2 downregulates A. actinomycetemcomitans- and P. gingivalis-LPS-induced ICAM-1 expression in HGF, via EP2/EP4 receptors by cAMP-dependent signaling pathways. The cAMP-elevating agents such as EP2/EP4 receptor activators may serve to control inflammatory and immune responses in periodontal disease.

Aggregatibacter actinomycetemcomitans↗

PubMed2001

Prostaglandin F2alpha upregulates interleukin-6 production in human gingival fibroblasts.

Prostaglandin F2alpha (PGF2alpha) is a bioactive lipid mediator which has been suggested to be involved in the pathogenesis of periodontal disease. However, the roles of PGF2alpha in periodontal lesions are poorly understood. In the present study, we investigated the effect of PGF2alpha on interleukin (IL)-6 production in human gingival fibroblasts (HGF). PGF2alpha stimulated IL-6 production in a time- and concentration-dependent fashion. IL-1beta and tumor necrosis factor alpha (TNFalpha), proinflammatory cytokines, induced IL-6 production in a time-dependent manner, and PGF2alpha synergistically enhanced IL-6 production induced by IL-1beta and TNFalpha. IL-6 mRNA was expressed in PGF2alpha-stimulated HGF, and PGF2alpha increased IL-6 mRNA levels induced by IL-1beta and TNFalpha. Fluprostenol, a selective FP receptor agonist, could mimic PGF2alpha-induced IL-6 production. Since FP receptors are coupled to elevation of intracellular calcium and activation of protein kinase C (PKC), the mechanism of IL-6 production by PGF2alpha was investigated using TMB-8, an inhibitor of Ca2+ mobilization from intracellular stores, and calphostin C, an inhibitor of PKC. TMB-8 significantly suppressed PGF2alpha-induced IL-6 production, whereas calphostin C showed a stimulatory effect on PGF2alpha-induced IL-6 production. From these data, we suggest that PGF2alpha upregulates IL-6 production through FP receptors in HGF, that PGF2alpha synergistically enhances IL-6 production in IL-1beta- and TNFalpha-stimulated HGF, and that PGF2alpha-induced IL-6 production may be dependent on intracellular Ca2+ mobilization and be downregulated by PKC activation. PGF2alpha may be involved in the pathogenesis of periodontal disease by enhancing IL-6 levels in periodontal lesions.

Calcium↗

PubMed2001

Involvement of cyclooxygenase-2 in serum-induced prostaglandin production by human oral gingival epithelial cells.

The purpose of the present study was to investigate the involvement of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in prostaglandin (PG) production by human oral gingival epithelial (OGE) cells stimulated with proinflammatory cytokines including interleukin(IL)-1alpha, IL-1alpha and tumor necrosis factor alpha (TNFalpha), and serum. Fetal bovine serum (FBS)-stimulated OGE cells produced significant levels of PGE2, whereas IL-1alpha, IL-1beta and TNFalpha could not induce significant PGE2 production. FBS induced PGE2 production in a dose- and time-dependent manner. NS-398, a selective COX-2 inhibitor, inhibited PGE2 production by FBS-stimulated cells as completely as indomethacin, a non-selective COX-1/COX-2 inhibitor. Expression of COX-2 protein in FBS-stimulated cells was increased, compared with that in unstimulated cells, whereas COX-1 protein expression was similar both in unstimulated and in FBS-stimulated cells. COX-2 mRNA was detected in FBS-stimulated cells, but not in unstimulated cells. We suggest that COX-2 is responsible for PG production by human OGE cells stimulated with serum and that OGE cells may be involved in PG production in periodontal lesions. Selective COX-2 inhibitors, which have the advantage of reduced gastric toxicity, may provide a useful approach to treatment of periodontal disease.

Analysis of Variance↗

PubMed2001

Upregulation of matrix metalloproteinase-1 production by prostaglandin F2alpha in human gingival fibroblasts.

In the present study, we investigated the effect of prostglandin F2alpha (PGF2alpha) and combination of PGF2alpha and interleukin(IL)-1beta on matrix metalloproteinase (MMP)-1 production in human gingival fibroblasts (HGF). PGF2alpha enhanced MMP-1 production in a dose-dependent manner in HGF. Combination of PGF2alpha and IL-1beta induced a synergistic increase of MMP-1 production in HGF. Furthermore, fluprostenol, a specific FP receptor agonist, increased MMP-1 production and induced a synergistic enhancement of IL-1beta-induced MMP-1 production in HGF, similar to PGF2alpha. FP receptor mRNA expression was detected in HGF, by reverse transcription-polymerase chain reaction. Northern blot analysis revealed that PGF2alpha enhanced MMP-1 mRNA expression in HGF and that PGF2alpha increased MMP-1 mRNA levels induced by IL-1beta. In conclusion, we suggest that PGF2alpha increases MMP-1 production in HGF and synergistically enhances MMP-1 production in IL-1beta-stimulated HGF. PGF2alpha may be involved in degradation of connective tissue in periodontal lesions.

Blotting, Northern↗

PubMed2001

A novel point mutation (C571T) in the tissue-non-specific alkaline phosphatase gene in a case of adult-type hypophosphatasia.

OBJECTIVE: Hypophosphatasia (HOPS) is an inheritable disorder characterized by defective skeletal mineralization, deficiency of tissue-non-specific alkaline phosphatase (TNSALP) activity and premature loss of deciduous teeth. The gene for TNSALP is located on chromosome 1p34-36.1 and consists of 12 exons and 11 introns. In this study we analysed the genomic TNSALP gene from a patient with HOPS, her family, and unrelated normal controls. MATERIALS AND METHODS: The proband was a 52-year-old Japanese woman with adult onset HOPS. The patient showed deficiency in alkaline phosphatase (ALP) activity, increased urinary excretion of phosphoethanolamine and severe periodontal disease. Genomic DNA was extracted from the peripheral leukocytes of the subjects. Based on published sequence data in the TNSALP gene, 11 pairs of polymerase chain reaction (PCR) primers were used to amplify the coding exons. The PCR amplified samples were subjected to PCR-single strand conformation polymorphism (SSCP) analysis and PCR-allele specific oligonucleotide (ASO) analysis. RESULTS: By PCR-SSCP analysis of the patient's genomic DNA, fragments containing exon 5 revealed abnormal mobility. This abnormal mobility (exon 5) was also found in the genomic DNA in her mother's sister, but were not detected in her father, brothers or sisters, and unrelated normal controls. Sequencing analysis of the abnormal band extracted from the SSCP gel revealed a C to T transition at nucleotide position 571 (C571T) in exon 5. This mutation resulted in a substitution of Ala-115 with a Val in the mature TNSALP polypeptide. PCR-ASO analysis also confirmed this missense point mutation. The result of this study showed that the pro-band has inherited the C571T mutation in exon 5 from her mother alone and the disease in this family was inherited as an autosomal dominant trait from the pedigree. CONCLUSIONS: The C571T mutation is a new missense point mutation and appears to cause significant changes in the structure and function of TNSALP because Ala-115 is highly conserved in rat TNSALP and human tissue-non-specific, intestinal and placental ALPs.

Alanine↗

PubMed2001

Prediction of the potentially fertile period by urinary hormone measurements using a new home-use monitor: comparison with laboratory hormone analyses.

BACKGROUND: The study compared a new urinary hormone monitoring system, Clearview Primera Fertility Monitor (CPFM), with laboratory hormone analyses in the prediction of the potentially fertile period. METHODS: Thirty healthy female volunteers provided blood and early morning urine samples for one cycle. Serum oestradiol, progesterone and luteinizing hormone (LH), and urinary LH and oestrone-3-glucuronide (E3G) were measured. The fertility status of volunteers; Low, High or Peak, was collected from monitors and compared with the hormone measurements. RESULTS: There was agreement between the first day of peak fertility and the urinary LH peak day in 65.6% of cycles and detection 1 or 2 days before the urinary LH peak day in 24.1 and 6.9% of cycles respectively. In 58.6% of cycles the system detected up to 5 days of increased fertility prior to the urinary LH peak day. Warning days of the urinary LH peak were similarly determined using defined thresholds of E3G and oestradiol providing up to 5 days warning in 82.8 and 96.6% of cycles respectively. CONCLUSIONS: The system can provide couples attempting to conceive with information about the potentially fertile days in the cycle in order that they may time intercourse. It also has potential for use in evaluation and treatment of infertile couples.

Adult↗

PubMed2001

Rapid detection and quantification of five periodontopathic bacteria by real-time PCR.

The quantity of periodontopathic bacteria in plaque samples is an important determinant for understanding the etiologic role of bacteria. The real-time PCR method was used to detect and quantify periodontopathic bacteria, such as Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis, Treponema denticola, and Treponema socranskii, in saliva and subgingival plaque samples. There was good agreement between the results of conventional PCR and real-time PCR methods. Using the LightCycler system we were able to determine the amount of periodontopathic bacteria within an hour. The real-time PCR method was linear for samples containing from 10(3) to more than 10(8) cells (r2 = 0.999). The application of the real-time PCR method should be useful in the rapid detection and quantification of periodontopathic bacteria in clinical samples.

Actinobacillus↗

PubMed2001

Treponema socranskii, Treponema denticola, and Porphyromonas gingivalis are associated with severity of periodontal tissue destruction.

BACKGROUND: The aim of the present study was to identify Treponema socranskii in addition to Treponema denticola and Porphyromonas gingivalis by polymerase chain reaction (PCR), and to clarify the relationship between the presence of these microorganisms and the severity of clinical periodontal parameters. METHODS: Saliva and subgingival plaque collected from 123 subjects (38 aggressive periodontitis patients, 65 chronic periodontitis patients, 20 healthy patients) were subjected to PCR to detect the aforementioned 3 microorganisms. RESULTS: Detection frequencies of T. socranskii, T. denticola, and P. gingivalis in plaque samples from aggressive periodontitis patients (71.1%, 73.7%, 84.2%, respectively) and chronic periodontitis patients (89.2%, 93.8%, 95.3%) were much higher than those from healthy subjects (30%, 5.0%, 10.0%). In aggressive and chronic periodontitis patients, these 3 species of bacteria were detected frequently at sites that showed deep periodontal pockets and severe attachment loss. The percentage of these bacteria-positive sites increased as the gingival index score of chronic periodontitis patients increased. T. socranskii was frequently detected together with T. denticola or P. gingivalis at the same sites, and coexistence of these microorganisms was frequently observed in deep periodontal pockets of aggressive periodontitis patients. CONCLUSIONS: T. socranskii, T. denticola, and P. gingivalis were frequently detected in periodontitis patients by PCR. The prevalence of these 3 microorganisms was correlated with various clinical parameters. Taken together, our findings suggest that T. socranskii, T. denticola, and P. gingivalis are associated with the severity of periodontal tissue destruction.

Adolescent↗

PubMed2001

Papillon-Lefèvre syndrome: serum immunoglobulin G (IgG) subclass antibody response to periodontopathic bacteria. A case report.

BACKGROUND: Papillon-Lefevre syndrome (PLS) is a rare autosomal recessive disorder which is characterized by palmar-plantar hyperkeratosis and rapid periodontal destruction of both primary and permanent dentitions. In this case report, we present clinical features, and microbiological and immunological findings of 40 month-old Thai male PLS patient. METHODS: Microbiological examinations consisted of bacterial culture methods utilizing selective media, morphological identification, and biochemical tests. In addition, the specific serum IgG subclass antibody titers reactive with etiologic periodontal bacteria were determined by the dot-blot immunological analysis and enzyme linked immunosorbent assay (ELISA). RESULTS: The examinations revealed that the patient harbored 3 major suspected periodontopathic microorganisms, A. actinomycetemcomitans, P. gingivalis, and P. intermedia. The patient's serum IgG1, IgG2, and IgG3, but not IgG4, titers against A. actinomycetemcomitans were dramatically increased. The predominant IgG subclass was IgG1. In contrast, the IgG titers against other tested bacteria, P. gingivalis, P. intermedia, and F. nucleatum, appeared to be similar to those of a healthy control. CONCLUSIONS: A. actinomycetemcomitans seems to play a pivotal role in the bacteria-host interaction in PLS periodontal pathogenesis. Response of the specific serum IgG subclass antibody titers against the A. actinomycetemcomitans antigen has been demonstrated. This association warrants further investigation.

Actinobacillus Infections↗

PubMed2001

Brain interleukin-1 is involved in blood interleukin-6 response to immobilization stress in rats.

Interleukin (IL)-6, a cytokine for host defense responses to infection and inflammation, is known to be induced by non-invasive physical or psychological stress, too. To test possible involvement of brain IL-1 in the stress-induced IL-6 production, IL-1 mRNA expression in the hypothalamus, in parallel with blood IL-6 level, was examined in rats subjected to restriction of their movement (immobilization stress). When rats were immobilized, the hypothalamic IL-1 beta mRNA level was increased in 1 hr, followed by progressive rises in the serum IL-6 level. The immobilization-induced rise in serum IL-6 was mimicked by intracerebroventricular (icv) administration of IL-1 beta under normal conditions, whereas it was attenuated by icv injection of an IL-1 receptor antagonist. These results indicate that IL-1 in the hypothalamus plays a pivotal mediating role in the stress-induced peripheral IL-6 production.

Animals↗

PubMed2001

Non-anastomotic midgraft stenosis of a knitted Dacron graft after arterial reconstruction. Report of a case.

Midgraft stenosis of the prosthesis after bypass surgery has seldom been reported. A man presented with an ischemic ulcer of the left foot. He had undergone bilateral femoropopliteal bypass surgery as well as left-sided iliofemoral bypass surgery with a knitted Dacron graft. The graft in his left thigh was occluded. A knitted Dacron conduit with 8-mm diameter was interposed between the iliofemoral bypass graft and the left profunda femoris artery, and graft-popliteal jumping bypass surgery was added. The postoperative angiogram showed a short-segmental severe stenosis of the interposed graft neighboring the proximal anastomosis. Repeat surgery showed that the stenotic lesion was located separately from the anastomosis. This midgraft stenosis was considered to consist of dissection of pseudointima associated with the intraoperative procedures. In cases of repeat surgery around the inguinal ligament, procedures should be performed with great care.

Aged↗

PubMed2001

[Thrombosis of the abdominal aorta in a patient with nephrotic syndrome].

Nephrotic syndrome frequently causes thromboembolic complications in veins. Arterial thrombosis, however, is relatively rare. We report the case of a 47-year-old male with nephrotic syndrome complicated with abdominal aortic thrombosis. The patient complained of pain in the bilateral lower extremities 2 weeks after the development of nephrotic syndrome. The aortogram revealed complete occlusion of the abdominal aorta just below the origin of the inferior mesenteric artery. Necrosis of the legs extended rapidly, and he eventually lost his legs. Among various predisposing factors, hypercoagulability associated with nephrotic syndrome seemed to be responsible for the development of thrombosis. Thrombotic complications are sometimes serious in the nephrotic patient. Assessment for the risk factors is required to warrant prophylactic anticoagulation.

Amputation, Surgical↗

PubMed2000

Central leptin suppresses splenic lymphocyte functions through activation of the corticotropin-releasing hormone-sympathetic nervous system.

Leptin is one of the key afferent signals that regulate food intake and energy expenditure by acting on specific receptors in the hypothalamus. Recently, leptin was reported to activate the peripheral immune system by acting directly on lymphocytes. To elucidate the brain-mediated participation of leptin in the modulation of peripheral immune functions, we examined the effects of intracerebroventricular (icv) injection of murine recombinant leptin on the proliferative response to Concanavalin A (ConA response) of splenic lymphocytes in rats. The ConA response of splenic lymphocytes was markedly reduced 30 min after icv injection of leptin. The suppressive effect of leptin was abolished completely either by surgical severing of the splenic nerves or by icv injection of an antibody against corticotropin-releasing hormone (CRH), but only partially by an anti-urocortin antibody. Icv injection of CRH and urocortin also suppressed the ConA response of splenic lymphocytes, and the effect of urocortin was prevented by the anti-CRH antibody, while that of CRH was not prevented by the anti-urocortin antibody. These results suggest that leptin suppresses peripheral lymphocyte functions, in contrast to the direct activating effects, indirectly through the activation of the CRH (urocortin)-sympathetic nervous system.

Animals↗