LIGHT, a member of the TNF superfamily, induces morphological changes and delays proliferation in the human rhabdomyosarcoma cell line RD

LIGHT is a member of the tumor necrosis factor (TNF) superfamily, which binds two known receptors, lymphotoxin-beta receptor (LTbetaR) and the herpesvirus entry mediator (HVEM)/TR2. We investigated the effects of LIGHT on the human rhabdmyosarcoma cell line RD. LIGHT delayed cell proliferation and induced morphological changes of the cells. These effects were not shown by other TNF family ligands such as TNFalpha and LTalpha, which induced the transcriptional activity of nuclear factor-kappaB (NF-kappaB) and NF-kappaB-responsible chemokine productions in the same manner as did LIGHT. LTalpha1beta2, another TNF family ligand for LTbetaR, was shown to have similar activities in RD cells as LIGHT. Both LIGHT and LTalpha1beta2 induced the expression of muscle-specific genes such as smooth muscle (SM) alpha-actin, while TNFalpha and LTalpha did not. These findings indicate that LIGHT may be a novel inducer of RD cell differentiation associated with SM alpha-actin expression through the LTbetaR.

Evaluation of posttreatment response of hepatocellular carcinoma with contrast-enhanced coded phase-inversion harmonic US: comparison with dynamic CT

PURPOSE

To assess the reliability of contrast material-enhanced real-time gray-scale ultrasonography (US) in evaluating posttreatment response of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Fifty HCC nodules were examined with contrast-enhanced coded phase-inversion harmonic US before and after treatment. Intratumoral vascularity was assessed with continuous imaging in the early arterial phase and with interval-delay scanning to depict tumor parenchymal flow during the blood pool phase. Vascular findings at US were compared with those at dynamic computed tomography (CT).

RESULTS

In 50 HCC nodules before treatment, positive enhancement of tumor vessels and tumor parenchymal flow (stain) were observed in 47 (94%) and 46 (92%), respectively. Either tumor vessel or stain was visualized with coded harmonic US in 49 of 50 nodules. Eighty-one coded harmonic US studies were performed in 49 posttreatment HCC nodules. Compared with dynamic CT, the sensitivity, specificity, and accuracy of coded harmonic US in helping to detect positive enhancement in pretreatment HCC were 98% (49 of 50), 100% (50 of 50), and 98% (49 of 50), respectively. After treatment, positive enhancement of tumor vascularity was observed in 39 (48%) of 81 posttreatment studies, and no enhancement was observed in others (52%). Coded harmonic US demonstrated partial and no enhancement of tumor vascularity in four and one nodule, respectively; after transcatheter arterial embolization with iodized oil, evaluation of tumor vascularity with dynamic CT was difficult because of the presence of oil.

CONCLUSION

With enhancement, coded harmonic US depicted tumor vascularity by showing tumor vessels in a real-time fashion at continuous imaging and tumor parenchymal flow at interval-delay scanning.

Characteristics and distribution of endogenous RFamide-related peptide-1

We have recently identified RFamide-related peptide (RFRP) gene that would encode three peptides (i.e., RFRP-1, -2, and -3) in human and bovine, and demonstrated that synthetic RFRP-1 and -3 act as specific agonists for a G protein-coupled receptor OT7T022. However, molecular characteristics and tissue distribution of endogenous RFRPs have not been determined yet. In this study, we prepared a monoclonal antibody for the C-terminal portion of rat RFRP-1. As this antibody could recognize a consensus sequence among the C-terminal portions of rat, human, and bovine RFRP-1, we purified endogenous RFRP-1 from bovine hypothalamus on the basis of immunoreactivity to the antibody. The purified bovine endogenous RFRP-1 was found to have 35-amino-acid length that corresponds to 37-amino-acid length in human and rat. We subsequently constructed a sandwich enzyme immunoassay using the monoclonal antibody and a polyclonal antibody for the N-terminal portion of rat RFRP-1, and analyzed the tissue distribution of endogenous RFRP-1 in rats. Significant levels of RFRP-1 were detected only in the central nervous system, and the highest concentration of RFRP-1 was detected in the hypothalamus. RFRP-1-positive nerve cells were detected in the rat hypothalamus by immunohistochemical analyses using the monoclonal antibody. In culture, RFRP-1 lowered cAMP production in Chinese hamster ovary cells expressing OT7T022 and it was abolished by pre-treatment with pertussis toxin, suggesting that OT7T022 couples G(i)/G(o) in the signal transduction pathway.

Establishment of an optimized set of 406 microsatellite markers covering the whole genome for the Japanese population

Microsatellites, an essential tool for genetic linkage analyses, are selected in genetic studies on the basis of both informativeness and their positions with respect to one another on the genetic map. In order to establish a microsatellite marker set useful for linkage studies in the Japanese population, we first genotyped 64 unrelated Japanese subjects, using 400 microsatellite markers from a commercially available set (ABI PRISM Linkage Mapping Set-MD10) and then determined the allelic frequencies and heterozygosities for these marker loci in the population. In order to optimize the set, we replaced 41 markers having a heterozygosity lower than 0.6 with as many informative markers in the corresponding loci, and newly added six markers in the set to minimize the several gaps found at intervals of over 20 cM. We finally established a set comprising 406 microsatellites with average intervals of 9cM (maximum, 17 cM) and minimum heterozygosities of over 0.6 (mean, 0.76). All data generated in this study, including the specific polymerase chain reaction (PCR) primer sequences of the newly added markers, are freely available to all researchers at our web site. The genetic tool established here should facilitate genetic linkage studies of various hereditary diseases, especially in the Japanese.

Metastin suppresses the motility and growth of CHO cells transfected with its receptor

We recently reported having identified of the ligand for an orphan G-protein-coupled receptor, hOT7T175, as the gene product (68-121)-amide of the metastasis suppressor gene KiSS-1. We further showed that the ligand, which we named "metastin," inhibits chemotaxis and invasion of Chinese hamster ovary (CHO) cells transfected with hOT7T175 cDNA (CHO/h175) in vitro, and pulmonary metastasis of hOT7T175-transfected B16-BL6 melanomas in vivo. In the present study, we investigated the activity of metastin in CHO/h175 cells in greater detail. Metastin significantly suppressed motility in a chemotaxis assay and wound healing assay at 10-100 nM order concentrations. Two N-terminally truncated peptides, metastin(40-54) and metastin(45-54) inhibited the migration of CHO/h175 cells as potently as metastin itself. Metastin also inhibited the spreading, monolayer growth and colony formation in agar (0.8%) of CHO/h175 cells at 10-100 nM concentrations. These results indicate that metastin is a potent inhibitor of cell motility, leading to suppression of cell growth and antimetastatic activity, and suggest that low molecular chemical compounds could replace its activity as a novel antimetastatic agent.

Sonographic diagnosis of pancreatic islet cell tumor: value of intermittent harmonic imaging

We describe a case of nonfunctioning islet cell tumor of the pancreas diagnosed preoperatively by intermittent harmonic power Doppler imaging and digital subtraction gray-scale harmonic imaging and the use of the contrast agent SH U 508A (Levovist). Hypervascularity and tumor perfusion were clearly demonstrated with both harmonic imaging techniques in the early arterial phase. Sonographic findings were confirmed by other modalities and by histopathologic examination.

In vitro activity of linezolid against Gram-positive uropathogens of hospitalized patients with complicated urinary tract infections

The antimicrobial activity of linezolid, a recently developed antibiotic agent active against Gram-positive bacteria, was tested against pathogens from three different collections. (1) Uropathogens from hospitalized urological patients (1990/1991) with complicated and/or hospital-acquired UTIs; Urologic Clinic, Hospital St. Elisabeth, Straubing. (2) Uropathogens from a multi-centre study (1995/1996) comprising 37 urological centres throughout Germany. (3) MRSA isolates of patients and staff (1999/2000) within the Hospital St. Elisabeth, Straubing. Genotyping of the latter isolates was performed by pulsed-field-electrophoresis. The minimal inhibitory concentrations (MIC) of linezolid determined by an agar (Isosensitest) dilution method using a multipoint inoculator and an inoculum of 10(4) cfu per point ranged for methicillin susceptible Staphylococcus aureus (MSSA) (n=27) between 2 and 4 mg/l, for methicillin resistant S. aureus (MRSA) (n=35) between 1 and 2 mg/l, for methicillin susceptible coagulase-negative staphylococci (CNS) (MSSE) (n=67) between 0.5 and 4 mg/l, for methicillin resistant CNS (MRSE) (n=19) between 0.25 and 2 mg/l, for Enterococcus. faecalis (n=184) between 0.5 and 4 mg/l, for E. faecium (n=3) 2 mg/l and for Streptococcus spp. (n=4) between 0.25 and 1 mg/l, indicating that all strains were susceptible. According to the in vitro activity, linezolid may be considered a promising antibacterial agent for the treatment of complicated UTI caused by Gram-positive uropathogens. Thus, linezolid should be evaluated in a clinical study.

Hepatocellular carcinoma: depiction of tumor parenchymal flow with intermittent harmonic power Doppler US during the early arterial phase in dual-display mode

PURPOSE

To assess the effectiveness of contrast material-enhanced intermittent harmonic Doppler ultrasonography (US) in depicting tumor vessels and tumor parenchymal flow (stain) in hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Fifty-eight patients with 65 HCC nodules were examined by using intermittent harmonic power Doppler US and digital subtraction harmonic B-mode US, both with intravenous administration of SH U 508A. Vascular findings at early arterial phase harmonic US were classified as positive enhancement or nonenhancement, depending on the tumor vascularity relative to the surrounding liver parenchyma. These results were compared with those of three-phase helical dynamic computed tomography (CT).

RESULTS

For hypervascular HCCs, there was excellent depiction of tumor vessels and tumor stain with the two intermittent harmonic US methods. The sensitivity and specificity for depiction of tumor vascularity were 93% (41 of 44 nodules) and 100% (21 of 21), respectively, with intermittent harmonic power Doppler US and 86% (38 of 44) and 100% (21 of 21), respectively, with subtraction US, as compared with these values at dynamic CT. Attenuation was an important factor in the depictability of tumor vascularity at harmonic US.

CONCLUSION

Contrast-enhanced intermittent harmonic US enables noninvasive demonstration of tumor vessels and especially tumor stain in HCC.

Stimulation effect of galanin-like peptide (GALP) on luteinizing hormone-releasing hormone-mediated luteinizing hormone (LH) secretion in male rats

Galanin-like peptide (GALP) is a recently isolated hypothalamic peptide which has sequence homology to galanin and binds to galanin receptors with high affinity. It has been shown that GALP neurons are localized in the arcuate nucleus and that GALP-immunoreactive fibers are in close apposition with LHRH neurons in the medial preoptic area (MPA). In the present study, we found that intracerebroventricular (icv) administration of GALP increased the plasma LH level but did not change the levels of other hormones. Concomitantly, accumulation of c-Fos protein was dramatically increased in the nuclei of LHRH-positive cells in the MPA by icv GALP administration. Furthermore, the GALP-induced plasma LH response was completely abolished by pretreatment with Cetrorelix, a LHRH receptor antagonist. On the other hand, GALP did not affect the release of LH, FSH, TSH, ACTH, GH or PRL directly from dispersed rat pituitary cells in vitro. These results strongly suggest a role for GALP in the control of gonadotropin secretion through a hypothalamic mechanism involving the release of LHRH.

The generation and characterization of a cell line derived from a sporadic renal angiomyolipoma: use of telomerase to obtain stable populations of cells from benign neoplasms

Angiomyolipomas are benign tumors of the kidney derived from putative perivascular epithelioid cells, that may undergo differentiation into cells with features of melanocytes, smooth muscle, and fat. To gain further insight into angiomyolipomas, we have generated the first human angiomyolipoma cell line by sequential introduction of SV40 large T antigen and human telomerase into human angiomyolipoma cells. These cells show phenotypic characteristics of angiomyolipomas, namely differentiation markers of smooth muscle (smooth muscle actin), adipose tissue (peroxisome proliferator-activator receptor gamma, PPARgamma), and melanocytes (microophthalmia, MITF), thus demonstrating that a single cell type can exhibit all of these phenotypes. These cells should serve as a valuable tool to elucidate signal transduction pathways underlying renal angiomyolipomas.

A novel secreted tumor antigen with a glycosylphosphatidylinositol-anchored structure ubiquitously expressed in human cancers

In a search for novel genes expressed in human cancers, we identified one gene from an assembled expressed sequence tag database. Northern blot analysis revealed that the gene, termed alcan, was expressed in various types of human cancer cell lines and in the fetus, but not in normal tissues. The alcan gene is located on chromosome 6 and is encoded on a 246-amino-acid protein with weak homology to classical major histocompatibility complex class I. Its gene product, ALCAN, had hydrophobic amino acid clusters at both the N- and C-terminal regions and was predicted to be a glycosylphosphatidylinositol (GPI)-anchored membrane protein. Flow cytometric analysis revealed that ALCAN was detected on the surface of human cancer cells and on alcan-transfected CHO-K1 cells. ALCAN was also secreted from these cells, suggesting that some portion of the molecules was secreted by enzymatic cleavage by, for example, phospholipases. Mutational analysis of ALCAN suggested that the GPI-anchored position was the Ser(216) residue. These findings indicate that ALCAN may be a potential target for cancer diagnosis or therapy.

Cloning of a novel G protein-coupled receptor, SLT, a subtype of the melanin-concentrating hormone receptor

A DNA fragment encoding an amino acid sequence possessing common features to the G protein-coupled receptor (GPCR) superfamily was found in the human genomic sequence, and from this information, the full-length cDNA of a novel GPCR, designated SLT, was cloned from the human hippocampus cDNA library. SLT showed the highest homology to the melanin-concentrating hormone (MCH) receptor, SLC-1 (31.5% identity), and to a lesser extent, to the somatostatin (SST) receptor subtypes. MCH exhibited agonistic behavior when applied to the SLT-expressing CHO cells at subnanomolar doses whereas more than 200 known peptides, including SST and cortistatin, did not. These results indicated that MCH is the cognate ligand of the SLT receptor and that this newly cloned GPCR is the second subtype of the MCH receptor. Quantitative polymerase chain reaction analysis of the SLT gene expression in human tissues showed that the SLT receptor is expressed mainly in brain areas including the cerebral cortex, amygdala, hippocampus, and corpus callosum, as well as in a limited number of peripheral tissues. The distribution of the SLT nearly overlapped that of SLC-1, suggesting that some of the neural functions of MCH may be mediated by both of these receptor subtypes.

Metastasis suppressor gene KiSS-1 encodes peptide ligand of a G-protein-coupled receptor

Metastasis is a major cause of death in cancer patients and involves a multistep process including detachment of cancer cells from a primary cancer, invasion of surrounding tissue, spread through circulation, re-invasion and proliferation in distant organs. KiSS-1 is a human metastasis suppressor gene, that suppresses metastases of human melanomas and breast carcinomas without affecting tumorigenicity. However, its gene product and functional mechanisms have not been elucidated. Here we show that KiSS-1 (refs 1, 4) encodes a carboxy-terminally amidated peptide with 54 amino-acid residues, which we have isolated from human placenta as the endogenous ligand of an orphan G-protein-coupled receptor (hOT7T175) and have named 'metastin'. Metastin inhibits chemotaxis and invasion of hOT7T175-transfected CHO cells in vitro and attenuates pulmonary metastasis of hOT7T175-transfected B16-BL6 melanomas in vivo. The results suggest possible mechanisms of action for KiSS-1 and a potential new therapeutic approach.

Possible risk reduction in esophageal cancer associated with MPO -463 A allele

Myeloperoxidase (MPO), an enzyme found in lysosomes of phagocytes, causes hydroxy radicals linked to DNA damage and activation of smoking related carcinogens. A -463 G/A polymorphism in the promoter region of the MPO gene results in reduced gene expression, which would imply lower susceptibility of esophageal cancer in mutant carriers. We conducted case-control study to test this hypothesis. Cases were 91 patients with esophageal cancer and controls were 241 non-cancer outpatients. MPO genotypes were examined by PCR-RFLP. The allele frequency for MPO -463A was found to be 8.2% for cases and 10.5% for controls. The age, sex, smoking and drinking status adjusted odds ratio for all subjects for MPO -463 GG/GA as compared to the AA was 0.61 (95% CI: 0.28-1.32). The adjusted odds ratio for the GG/GA genotype was significantly low (0.15; 0.03-0.76, P=0.022) for those aged 61 years or older who had a significantly higher odds ratio for smoking than younger subjects. No difference was observed in disease risk when prevalent and incident cases were compared. Although there are limitations for interpretation of this study because of prevalent case-control study and partial statistical significance, these results suggest that MPO -463 A allele reduce the risk of esophageal cancer.

Molecular properties of apelin: tissue distribution and receptor binding

We analyzed the tissue distribution of apelin mRNA in rats by a quantitative reverse transcription-polymerase chain reaction and that of immunoreactive apelin (ir-apelin) by an enzyme immunoassay (EIA) using a monoclonal antibody. The expression levels of apelin mRNA and ir-apelin seemed to be consistent among tissues: they were highly expressed in the lung and mammary gland. By the combination of gel filtration and EIA, we found that the molecular forms of apelin differ among respective tissues: apelin molecules with sizes close to apelin-36 (long forms) were major components in the lung, testis, and uterus, but both long and short (whose sizes were close to [<Glu(65)]apelin-13) forms were detected in the mammary gland. In Scatchard analyses, the radioiodinated apelin-36 analogue bound to the receptor, APJ, with high affinity. In competitive binding assays, apelin-36 and apelin-19 far more efficiently inhibited the binding of the labeled apelin-36 analogue with APJ than [<Glu(65)]apelin-13. In analyses for the dissociation of apelin from APJ, unlabeled apelin-36 replaced more rapidly the labeled apelin-36 analogue bound with APJ than [<Glu(65)]apelin-13. Our results demonstrate that the long and short forms of apelin differently interact with APJ.

Distribution of galanin-like peptide in the rat brain

Galanin-like peptide (GALP) is a novel galanin-like peptide isolated from the porcine hypothalamus. To determine the distribution of GALP in the rat brain, we performed immunohistochemical studies using a monoclonal antibody toward the N-terminal sequence of GALP. GALP-immunoreactive neuronal cell bodies were observed only in the arcuate nucleus (Arc), which was further confirmed by in situ hybridization studies using digoxigenin-labeled antisense GALP riboprobe. Additional immunostained cells were found in the median eminence and infundibular stalk. The GALP neurons found in the Arc were further characterized by double label immunohistochemistry. More than 85% of the GALP neurons were immunostained with leptin receptor antibody. However, the GALP neurons and fibers found in the Arc were not labeled with alpha-MSH, somatostatin, neuropeptide Y, agouti-related protein, or galanin antibodies, indicating that GALP is found in neurons other than these known Arc neurons. Dense staining of GALP-containing fibers was found in the anterior parvicellular part of the paraventricular hypothalamic nucleus, in the ventral part of the lateral septal nucleus, and in the bed nucleus of the stria terminalis. Relatively dense staining was noted in the medial preoptic area (MPA), and weak staining was noted in the periventricular hypothalamic nucleus. Detailed double labeling studies in the paraventricular hypothalamic nucleus demonstrated that GALP-containing fibers converged in a more rostral direction than did agouti-related protein-containing fibers. Furthermore, GALP-immunoreactive fibers were in close apposition with GnRH-immunoreactive fibers in the MPA and bed nucleus of the stria terminalis, and about 6% of GnRH-positive neurons in the MPA showed close contact with the GALP-immunoreactive fibers. Our findings indicate that GALP neurons, as leptin-responsive neurons, may participate in the regulation of feeding behavior and/or reproductive functions.

Contrast-enhanced subtraction harmonic sonography for evaluating treatment response in patients with hepatocellular carcinoma

OBJECTIVE

Our objective was to assess the usefulness of contrast-enhanced subtraction harmonic sonography in evaluating the treatment response of patients with hepatocellular carcinoma.

SUBJECTS AND METHODS

Thirty-two hepatocellular carcinoma lesions in 26 patients (age range, 44-85 years; mean age, 66 years) were examined with Levovist-enhanced intermittent harmonic imaging before and after therapy. A Toshiba Powervision 8000 was used. A subtraction image was obtained by digitally subtracting the last-frame harmonic image from the first-frame image when multishot mode was preset. Results of contrast-enhanced CT were compared with the results of subtraction harmonic imaging.

RESULTS

Before therapy, an enhancement pattern of tumor vascularity was seen for 93.8% (30/32) of hepatocellular carcinoma nodules on subtraction harmonic imaging. After therapy, subtraction harmonic imaging showed 46.7% (14/30) enhancement (incomplete tumor necrosis) and 53.3% (16/30) no enhancement (complete tumor necrosis). When dynamic CT was the gold standard, the sensitivity, specificity, and accuracy of subtraction harmonic imaging were 93.3%, 100%, and 96.7%, respectively. Intratumoral flow signals in hepatocellular carcinoma after therapy on harmonic imaging were used as a guide to target additional percutaneous therapy.

CONCLUSION

Digital subtraction contrast-enhanced harmonic imaging can depict tumor vascularity in hepatocellular carcinoma after therapy sensitively and accurately. Because it is easy to perform and provides real-time needle insertion guidance, it may be preferable to perform after localized therapy to monitor treatment response, which will reduce unnecessary CT scanning.

Conformation of a peptide ligand bound to its G-protein coupled receptor

Many peptide hormones elicit a wide array of physiological effects by binding to G-protein coupled receptors. We have determined the conformation of pituitary adenylate cyclase activating polypeptide, PACAP(1--21)NH(2), bound to a PACAP-specific receptor by NMR spectroscopy. Residues 3--7 form a unique beta-coil structure that is preceded by an N-terminal extended tail. This beta-coil creates a patch of hydrophobic residues that is important for receptor binding. In contrast, the C-terminal region (residues 8--21) forms an alpha-helix, similar to that in the micelle-bound PACAP. Thus, the conformational difference between PACAP in the receptor-bound and the micelle-bound states is limited to the N-terminal seven residues. This observation is consistent with the two-step ligand transportation model in which PACAP first binds to the membrane nonspecifically and then diffuses two-dimensionally in search of its receptor; a conformational change at the N-terminal region then allows specific interactions between the ligand and the receptor.

Quantitative analysis of gene expressions related to inflammation in canine spastic artery after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The possible role of inflammatory reaction of the cerebral artery in the pathogenesis of cerebral vasospasm has been noted in recent studies. We quantitatively measured the levels of expression of genes related to inflammation in the spastic artery in a canine double-hemorrhage model.

METHODS

Twenty dogs were assigned to 4 groups: group D0, control; group D2, dogs killed 2 days after cisternal injection of blood; group D7, dogs given double cisternal injections of blood and killed 7 days after the first injection; and group D14. Angiography was performed twice: on the first day and before the animals were killed. Total RNA was extracted from the basilar artery. The expressions of interleukin (IL)-1alpha, IL-6, IL-8, IL-10, tumor necrosis factor-alpha, E-secretin, fibronectin, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule-1, transforming growth factor-ss, basic fibroblast growth factor, and collagen types I, III, and IV were examined with TaqMan real-time quantitative reverse transcription-polymerase chain reaction.

RESULTS

Prolonged arterial narrowing peaking on 7 day was observed. There was a significant difference in vessel caliber between D0, D2, D7, and D14 groups (P:<0.0001). There were significant differences in mRNA expression in the basilar artery for IL-1alpha, IL-6, IL-8, ICAM-1, and collagen type I between D0, D2, D7, and D14 groups (P:=0.0079, 0. 0196, 0.0040, 0.0017, and <0.0001, respectively). The average level of mRNA was highest in D7 for IL-1alpha, IL-6, IL-8, and ICAM-1 (17-, 16-, 131-, and 1.7-fold compared with those of D0, respectively) and in D14 for collagen type I (10.9-fold).

CONCLUSIONS

Increased expression of genes related to inflammation in the spastic artery suggests that inflammatory reaction of the cerebral artery is associated with sustained contraction.

Methicillin-resistant coagulase-negative staphylococci isolated from healthy horses in Japan

OBJECTIVE

To determine patterns of methicillin-resistant staphylococci isolated from apparently healthy horses.

SAMPLE POPULATION

44 horses from 8 riding clubs in Japan.

PROCEDURE

Methicill in-resistant staphylococci were isolated from the skin or nares, using a selective medium containing a beta-(symboric) lactam antibiotic, ceftizoxime. Clonality of isolates was determined by use of pulsed-field gel electrophoresis. Detection of mecA, mecl, and mecR1 genes was accomplished by use of polymerase chain reactions.

RESULT

Of the 44 horses, 13 (29.5%) yielded 15 isolates of methicillin-resistant staphylococci. The 15 isolates were identified as 6 species (Staphylococcus epidermidis, S lentus, S saprophyticus, S xylosus, S sciuri, and S haemolyticus). However, methicillin-resistant S aureus was seldom isolated. Each isolate contained the mecA gene and had a high resistance to beta-lactam antibiotics. Some isolates also were resistant to other antibiotics such as erythromycin and kanamycin.

CONCLUSIONS AND CLINICAL RELEVANCE

Methicillin-resistant coagulase-negative staphylococci that were highly resistant to various antibiotics were isolated from apparently healthy horses in Japan. These organisms must be considered a potential threat to horses and veterinarians who care for them.

New neuropeptides containing carboxy-terminal RFamide and their receptor in mammals

Only a few RFamide peptides have been identified in mammals, although they have been abundantly found in invertebrates. Here we report the identification of a human gene that encodes at least three RFamide-related peptides, hRFRP-1-3. Cells transfected with a seven-transmembrane-domain receptor, OT7T022, specifically respond to synthetic hRFRP-1 and hRFRP-3 but not to hRFRP-2. RFRP and OT7T022 mRNAs are expressed in particular regions of the rat hypothalamus, and intracerebroventricular administration of hRFRP-1 increases prolactin secretion in rats. Our results indicate that a variety of RFamide-related peptides may exist and function in mammals.

Identification and functional characterization of a novel subtype of neuromedin U receptor

Neuromedin U is a bioactive peptide isolated originally from the porcine spinal cord. We recently identified neuromedin U as the cognate ligand for the orphan G protein-coupled receptor FM-3. In this study, we isolated cDNA coding for a novel G protein-coupled receptor, TGR-1, which was highly homologous with FM-3. We found that neuromedin U specifically and clearly elevated the extracellular acidification rates, arachidonic acid metabolite release, and intracellular Ca(2+) mobilization in Chinese hamster ovary cells expressing TGR-1. Radiolabeled neuromedin U specifically bound with high affinity to membrane fractions prepared from these cells. These results show that TGR-1, like FM-3, is a specific and functional receptor for neuromedin U. We analyzed TGR-1 mRNA tissue distribution in rats using quantitative reverse transcription-polymerase chain reaction and found it to considerably differ from that of FM-3 mRNA. TGR-1 mRNA was primarily expressed in the uterus, suggesting that TGR-1 mediates the contractile activity of neuromedin U in this tissue. The identification of specific and functional receptor subtypes for neuromedin U will facilitate the study of their physiological roles and the search for their specific agonists and antagonists.

Molecular and functional characteristics of APJ. Tissue distribution of mRNA and interaction with the endogenous ligand apelin

We have recently identified apelin as the endogenous ligand for human APJ. In rats, the highest expression of APJ mRNA was detected in the lung, suggesting that APJ and its ligand play an important role in the pulmonary system. When apelin-36 and its pyroglutamylated C-terminal peptide, [<Glu(65)]apelin-13, were compared in microphysiometric analyses, the elevation of extracellular acidification induced in cells expressing APJ by [<Glu(65)]apelin-13 was transient, whereas that by apelin-36 was sustained. These responses were almost completely inhibited by a specific inhibitor for G(i) or that for Na(+)/H(+) exchanger. (125)I -Labeled [<Glu(65)]apelin-13 analogue specifically bound to APJ with a high affinity, and [<Glu(65)]apelin-13 was more potent than apelin-36 in competitive inhibition assays. Because pretreatment with apelin-36 but not [<Glu(65)]apelin-13 drastically reduced the binding of the labeled apelin to APJ, the different patterns of acidification induced by these two peptides appeared to reflect their dissociation rather than association with APJ. Apelin elicited the migration of APJ-expressing cells, and [<Glu(65)]apelin-13 was more potent than apelin-36 in this activity. Heterogeneous molecular forms of apelin corresponding to apelin-36 and [<Glu(65)]apelin-13 were produced in bovine colostrum. Apelin-36 and [<Glu(65)]apelin-13 might have different functions in vivo and in vitro.

Identification of neuromedin U as the cognate ligand of the orphan G protein-coupled receptor FM-3

Neuromedin U is a bioactive peptide first isolated from porcine spinal cord. In this paper, we demonstrate that neuromedin U is the cognate ligand for the orphan G protein-coupled receptor, FM-3, isolated originally as a homologue of neurotensin and growth hormone secretogogue receptors. Neuromedin U induced specific and evident elevation of extracellular acidification rates, arachidonic acid metabolite release, and intracellular Ca(2+) mobilization in Chinese hamster ovary cells expressing human FM-3. In addition, radiolabeled neuromedin U specifically bound to membrane fractions prepared from these cells with high affinity. We subsequently analyzed the tissue distribution of neuromedin U and FM-3 mRNAs in rats using quantitative reverse transcription-polymerase chain reaction. Neuromedin U mRNA was highly expressed in the gastrointestinal tract, and the highest expression was detected in the pituitary gland. On the other hand, FM-3 mRNA was highly expressed in the small intestine and lung, suggesting that neuromedin U plays important roles in these tissues. The identification of a specific and functional receptor for neuromedin U will facilitate studies on their physiological roles and the search for receptor agonists and antagonists.

Molecular cloning of a novel brain-type Na(+)-dependent inorganic phosphate cotransporter

We have isolated a human cDNA encoding a protein, designated DNPI, that shows 82% amino acid identity and 92% similarity to the human brain-specific Na(+)-dependent inorganic phosphate (Na(+)/P(i)) cotransporter (BNPI), which is localized exclusively to neuron-rich regions. Expression of DNPI mRNA in Xenopus oocytes resulted in a significant increase in Na(+)-dependent P(i) transport, indicating that DNPI is a novel Na(+)/P(i) cotransporter. Northern blot analysis shows that DNPI mRNA is expressed predominantly in brain, where the highest levels are observed in medulla, substantia nigra, subthalamic nucleus, and thalamus, all of which express BNPI mRNA at low levels. In contrast, DNPI mRNA is expressed at low levels in cerebellum and hippocampus, where BNPI mRNA is expressed at high levels. No hybridizing signal for DNPI mRNA is observed in the glia-rich region of corpus callosum. In other regions examined, both mRNAs are moderately or highly expressed. These results indicate that BNPI and DNPI, which coordinate Na(+)-dependent P(i) transport in the neuron-rich regions of the brain, may form a new class within the Na(+)/P(i) cotransporter family.

Analyses for susceptibility of rat anterior pituitary cells to prolactin-releasing peptide

We validated the effect of prolactin-releasing peptide (PrRP) on prolactin (PRL) secretion from rat anterior pituitary cells in in vitro culture. We found that culture conditions considerably influenced the response of the anterior pituitary cells to PrRP. Longer culture term (4 d) was required to obtain better responses of the anterior pituitary cells to PrRP in comparison to thyrotropin-releasing hormone (TRH). Under the culture conditions employed here, PrRP was comparable to TRH in the potency promoting PRL secretion, and the action of PrRP was very specific for PRL secretion. The susceptibility of the anterior pituitary cells to PrRP varied in female rats depending on the process of reproduction: the cells prepared from lactating rats were the most sensitive to PrRP compared with those from random-cycle and pregnant rats. Because the expression levels of PrRP receptor mRNA in the pituitary varied during the reproductive process, we speculated that the susceptibility of the anterior pituitary cells would reflect cellular changes including the expression level of PrRP receptors. In addition, treatment with estrogen in vivo enhanced the susceptibility of the cultured anterior pituitary cells in male rats. Our results indicate that the susceptibility of the rat anterior pituitary cells to PrRP is regulated by physiological mechanisms.

Clinical features of intracranial aneurysms in siblings

OBJECTIVE

Among the family members of patients with aneurysmal subarachnoid hemorrhage (SAH), siblings have been documented to be at high risk of SAH and to have a high prevalence of unruptured aneurysms. We studied the distinctive features of aneurysms in siblings and attempted to determine the risk of rupture.

METHODS

We analyzed detailed data on 159 patients with siblings who had ruptured and unruptured aneurysms in 77 families from throughout Japan.

RESULTS

Seventy-three percent of the patients were female, and the mean age at the time of rupture was 55.6 years. In 39 families, two or more siblings had SAH. Eighty of 107 patients with ruptured aneurysms and 28 of 52 with unruptured aneurysms had a family history of SAH in siblings (P = 0.0082). Multiple and mirror-image aneurysms were found in 42 and 21 patients, respectively. Among 218 aneurysms, middle cerebral artery aneurysms were the most common type (43%). Anterior communicating artery aneurysms were underrepresented (15%). There were significantly more ruptured than unruptured anterior communicating artery aneurysms, compared with other aneurysms (P = 0.01).

CONCLUSION

The clinical features of aneurysms in siblings in this population agreed well with those reported for familial intracranial aneurysms and SAH, except for the age at the time of rupture. It is suggested that the risk of rupture is greater when patients with unruptured aneurysms have siblings with aneurysmal SAH and/or anterior communicating artery aneurysms.

Stimulation of corticotropin-releasing hormone-mediated adrenocorticotropin secretion by central administration of prolactin-releasing peptide in rats

Prolactin-releasing peptide (PrRP) is a recently isolated hypothalamic peptide which is an endogenous ligand to an orphan receptor. We previously demonstrated that PrRP neurons are widely distributed throughout the rat brain and suggested that PrRP may have important functions in the central nervous system. To analyze the function of PrRP, we studied the effect of intracerebroventricular (i.c.v.) PrRP administration on c-Fos protein accumulation in the rat brain. The results clearly indicated that c-Fos protein accumulation was dramatically increased in the nuclei of corticotropin-releasing hormone (CRH)-positive parvocellular neurosecretory cells in the paraventricular nucleus (PVN). We also demonstrated synapse-like contact between PrRP neurons and CRH cell bodies in the PVN, which suggests that PrRP31 has some effect on CRH secretion. We therefore investigated the effect of i.c.v. administration of PrRP31 on the CRH-mediated increase in adrenocorticotropin (ACTH) levels, and found that plasma ACTH levels were indeed increased by i.c.v. PrRP31. In addition, animals pre-treated with intravenous alpha-helical CRH, a potent CRH antagonist, showed attenuated plasma ACTH responses after i.c.v. PrRP31 administration. These results strongly suggest that PrRP affects the hypothalamic-pituitary-adrenal axis.

Cloning of cDNA and the gene encoding human hepatocyte nuclear factor (HNF)-3 beta and mutation screening in Japanese subjects with maturity-onset diabetes of the young

AIMS/HYPOTHESIS

Molecular defects of the genes for transcription factors, hepatocyte nuclear factor (HNF)-4 alpha, HNF-1 alpha, HNF-1 beta and insulin promoter factor-1 cause maturity-onset diabetes of the young (MODY1, 3, 5, and 4, respectively). This suggests the HNF-related transcription cascade is important in insulin secretion which is induced by glucose. These genes and the gene encoding glycolytic enzyme glucokinase (MODY2) are, however, responsible for only 15-20% of cases of MODY in the Japanese. Searching for a novel form of MODY in this population, we cloned a new candidate gene encoding human HNF-3 beta, a winged helix transcription factor, which also belongs to the same HNF-transcription cascade.

METHODS

The cDNA clone for human HNF-3 beta was isolated from a liver cDNA library. The gene was also cloned from a genomic library and its organization and chromosomal localization were determined. We screened 68 Japanese subjects with MODY/early-onset diabetes for mutations in this gene.

RESULTS

Human HNF-3 beta is composed of 457 amino acids. The human gene, which was mapped to the segment 30 cR from SHGC-37039 on chromosome 20p by radiation hybrid mapping, spans approximately 4.5 kb and consists of three exons. Direct sequencing of the exons and flanking regions identified one missense mutation A328 V and seven polymorphisms, although the functional significance of the mutation in the pathogenesis of diabetes is not known.

CONCLUSION/INTERPRETATION

The characterization of the structure of the HNF-3 beta gene and its mapping in the framework of markers will be helpful in genetic studies of the various forms of diabetes mellitus.

Isolation and cDNA cloning of a novel galanin-like peptide (GALP) from porcine hypothalamus

Galanin is a widely distributed neuropeptide with a variety of physiological functions. Three galanin receptor subtypes, GALR1, GALR2, and GALR3, have been reported. We isolated a novel galanin-like peptide (GALP) from porcine hypothalamus by observing its activity for increasing [(35)S]GTPgammaS binding to a membrane preparation of GALR2-transfected cells. The peptide had 60 amino acid residues and a non-amidated C terminus. The amino acid sequence of GALP-(9-21) was completely identical to that of galanin-(1-13). A cloned porcine GALP cDNA indicated that GALP was processed from a 120-amino acid GALP precursor protein. The structures of rat and human GALP-(1-60) were deduced from cloned cDNA, which indicated that the amino acid sequences 1-24 and 41-53 were highly conserved between humans, rats, and pigs. Receptor binding studies revealed that porcine GALP-(1-60) had a high affinity for the GALR2 receptor (IC(50) = 0.24 nM) and a lower affinity for the GALR1 receptor (IC(50) = 4.3 nM). In contrast, galanin showed high affinity for the GALR1 (IC(50) = 0.097 nM) and GALR2 receptors (IC(50) = 0.48 nM). GALP is therefore an endogenous ligand that preferentially binds the GALR2 receptor, whereas galanin is relatively non-selective.

Central administration of prolactin-releasing peptide stimulates oxytocin release in rats

The prolactin-releasing peptide (PrRP) is a novel hypothalamic peptide that has been purified as a ligand of an orphan receptor which is expressed in pituitary cells, and is known to stimulate prolactin release both in vitro and in vivo. We previously determined the immunocytochemical localization of PrRP neurons in the rat brain and our results suggest that PrRP takes part in a variety of brain functions. Additionally, in rats we have demonstrated the synaptic contact of PrRP neurons with oxytocin cell bodies in the paraventricular hypothalamic nucleus (PVH) and supraoptic nucleus (SON). This observation indicates that PrRP may regulate oxytocin secretion. In the present study, we performed intra-cerebroventricular administration of PrRP to conscious rats, and examined the effect of PrRP on the plasma levels of oxytocin and vasopressin. Our results show that central administration of PrRP increased the plasma oxytocin and vasopressin levels in female rats, but in male rats only oxytocin was increased. These results suggest that the PrRP acts as a neuro-modulator of the function of magnocellular neurons, especially oxytocin neurons, in the brain.

Identification of genes differentially expressed in canine vasospastic cerebral arteries after subarachnoid hemorrhage

To understand the molecular processes of continuous vasospasm of cerebral arteries after subarachnoid hemorrhage, mRNA differential display and screening of cDNA expression array were performed to identify genes that are differentially expressed in vasospastic arteries of canine two-hemorrhage models. The expression levels of 18 genes were found to be upregulated, and those of two genes to be downregulated. Of these, 12 represent known genes or homologues of genes characterized previously, and the other eight genes are not related to any sequences in the databases. The known genes include five upregulated inflammation-related genes encoding monocyte chemotactic protein-1, cystatin B, inter-alpha-trypsin inhibitor family heavy chain-related protein, serum amyloid A protein, and glycoprotein 130, suggesting that inflammatory reaction may be involved in the development of cerebral vasospasm. The upregulation of three known genes encoding stress-related proteins of vascular endothelial growth factor, BiP protein, and growth-arrest and DNA-damage-inducible protein may be involved in possible cell survival in the damaged arteries. A full-length cDNA for the unknown clone DVS 27, whose expression was most highly upregulated, was isolated from the cerebral artery cDNA library by hybridization. Characterization of these genes should help to clarify the molecular mechanism of continuous cerebral vasospasm after subarachnoid hemorrhage.

Urotensin II is the endogenous ligand of a G-protein-coupled orphan receptor, SENR (GPR14)

Two molecular species of urotensin II (UII) were isolated from porcine spinal cords and identified as the endogenous ligands of a G-protein-coupled orphan receptor, SENR (sensory epithelium neuropeptide-like receptor), which is identical to GPR14. We established a CHO cell line stably expressing the rat SENR and investigated several tissue extracts to evoke the response mediated by the SENR. Extract from porcine spinal cords showed an activity of arachidonic acid metabolites release from SENR-expressing cells and was purified using HPLC. Two active substances were isolated and their sequences were determined as GPTSECFWKYCV and GPPSECFWKYCV, which were revealed to be porcine UII. Synthetic UII peptides caused arachidonic acid metabolites release activity in the rat SENR-expressing cells with an EC(50) value of 1 nM. Three cDNAs encoding the precursor proteins of porcine UII were cloned from a porcine spinal cord cDNA library; 2 consist of 121 amino acid residues and the other, which seemed to be a splicing variant, consist of 85 residues.

Apelin, the natural ligand of the orphan receptor APJ, is abundantly secreted in the colostrum

By using a strategy that we have developed to search for the ligands of orphan seven-transmembrane-domain receptors [S. Hinuma et al., Nature 393 (1998) 272-276], we have recently identified a natural ligand, apelin, for the orphan 7TMR, APJ [K. Tatemoto et al., Biochem. Biophys. Res. Commun. 251 (1998) 471-476]. In this paper, we isolated rat and mouse apelin cDNAs, and analyzed the tissue distribution of apelin mRNA in rats. Although apelin mRNA was widely detected in a variety of tissues, the highest expression of apelin mRNA was detected in the mammary gland of pregnant rats. In the mammary gland, biologically active apelin and its mRNA considerably increased during pregnancy and lactation, and reached a maximal level around parturition. Moreover, a large amount of apelin (14-93 pmol/ml) was found to be secreted in the bovine colostrum, and it was still detectable even in commercial bovine milk. Since apelin partially suppressed cytokine production by mouse spleen cells in response to T cell receptor/CD3 cross-linking, the oral intake of apelin in the colostrum and milk might modulate immune responses in neonates.

Tsc2(+/-) mice develop tumors in multiple sites that express gelsolin and are influenced by genetic background

Tuberous sclerosis (TSC) is an autosomal dominant genetic disorder in which benign hamartomas develop in multiple organs, caused by mutations in either TSC1 or TSC2. We developed a murine model of Tsc2 disease using a gene targeting approach. Tsc2-null embryos die at embryonic days 9.5-12.5 from hepatic hypoplasia. Tsc2 heterozygotes display 100% incidence of multiple bilateral renal cystadenomas, 50% incidence of liver hemangiomas, and 32% incidence of lung adenomas by 15 months of age. Progression to renal carcinoma, fatal bleeding from the liver hemangiomas, and extremity angiosarcomas all occur at a rate of less than 10%. The renal cystadenomas develop from intercalated cells of the cortical collecting duct and uniformly express gelsolin at high levels, enabling detection of early neoplastic lesions. The tumor expression pattern of the mice is influenced by genetic background, with fewer large renal cystadenomas in the outbred Black Swiss background and more angiosarcomas in 129/SvJae chimeric mice. The slow growth of the tumors in the heterozygote mice matches the limited growth potential of the great majority of TSC hamartomas, and the influence of genetic background on phenotype correlates with the marked variability in expression of TSC seen in patients.

Clinical outcome in localized renal cell carcinomas related to immunoexpression of proliferating cell nuclear antigen, Ki-67 antigen, and tumor size

This study was designed to clarify the relationship between clinical outcome and immunoexpression of proliferating cell nuclear antigen (PCNA) and Ki-67 antigen (Ki-67) in 71 localized renal cell carcinomas (RCCs) of Robson stage I and II, related to the disease recurrence and tumor size. PCNA and Ki-67 expressions showed significant differences between non-recurring and recurring groups and more variability in stage II than in stage I. Recurrence rates according to tumor size were 0% for </=2.5 cm, 4% for 2.5 to 5.0 cm, and 55.8% for >/=5.0 cm. It was concluded that PCNA and Ki-67 expression profiles were considered to be closely related to tumor stage and showed some promise for predicting the disease recurrence.

Tissue distribution of prolactin-releasing peptide (PrRP) and its receptor

Prolactin-releasing peptide (PrRP) is a novel bioactive peptide, originally isolated from bovine hypothalamus by utilizing an orphan seven-transmembrane-domain receptor expressed in the human pituitary gland. In this paper, we analyzed the tissue distribution of rat and human PrRP and their receptor mRNAs by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Northern blotting. In RT-PCR analysis, rat PrRP receptor mRNA was detected in the central nervous system, and the highest expression was detected in the pituitary gland. In addition, in situ hybridization revealed that rat PrRP receptor mRNA was highly expressed in the anterior lobe of the pituitary. On the other hand, rat PrRP mRNA was most abundantly expressed in the medulla oblongata, while significant levels of expression were widely detected in other tissues. In Northern blot analyses, human PrRP receptor mRNA was detected only in the pituitary gland among tissues examined. Human PrRP mRNA was detected in the medulla oblongata and in the pancreas. In contrast to the pattern of mRNA expression, the highest content of bioactive PrRP was found in the hypothalamus rather than the medulla oblongata in the rat brain, indicating that PrRP mRNA does not always parallel with mature PrRP in tissue distribution. The wide distribution of PrRP and its receptor suggests that they have various functions not only in the pituitary gland but also in the other tissues.

Isolation and identification of melanin-concentrating hormone as the endogenous ligand of the SLC-1 receptor

Melanin-concentrating hormone (MCH), which is an orexigenic peptide, was isolated and identified as the endogenous ligand of the SLC-1 receptor. We established a CHO cell line expressing the rat SLC-1 receptor to search for its endogenous ligand. The extract of rat whole brain showed inhibition of intracellular forskolin-induced cAMP accumulation in rat SLC-1-expressing CHO cells and was purified. Using HPLC purification, we isolated and identified MCH as the endogenous ligand of the SLC-1 receptor. The authentic MCH demonstrated a dose-dependent inhibitory effect on cAMP accumulation in forskolin-stimulated rat and human SLC-1-expressing CHO cells with an EC(50) value of 0.2 nM for both the rat and human SLC-1 receptors. This is the first description of the functional receptor for MCH.

Stimulation of prolactin release by prolactin-releasing peptide in rats

We have previously reported a hypothalamic peptide that shows specific prolactin (PRL)-releasing activity in vitro, named prolactin-releasing peptide (PrRP). However, its activity in vivo has not yet been shown. In this study, we examined whether PrRP could induce specific PRL release in vivo using normal cycling female and male rats. Intravenous injection of PrRP31 increased plasma PRL levels in rats in a dose-dependent manner. PrRP31 (50 nmol/kg i.v.) significantly (P < 0.05) stimulated plasma PRL levels within 25 min after injection in rats in proestrus, estrus, and metestrus. A higher dose of PrRP31 (500 nmol/kg i.v.) was necessary for a significant increase in plasma PRL levels in male rats. These results clearly indicate that female rats, especially at proestrus, are more sensitive to PrRP-induced PRL secretion than male rats. The effect of PrRP on PRL release is affected considerably by the estrous cycle and sex, which suggests that PrRP sensitivity is controlled by the endogenous hormonal milieu, such as estrogen levels. PrRP31 did not affect other pituitary hormone secretions. The results indicate that PrRP shows specific PRL-releasing activity in vivo as well as in vitro and suggest that it plays an important role in the regulation of PRL release under certain physiological conditions.

The quest for novel bioactive peptides utilizing orphan seven-transmembrane-domain receptors

Various sorts of bioactive molecules including hormones, neurotransmitters, and chemokines transmit signals into cells by binding to so-called seven-transmembrane-domain receptors (7TMRs). The recent progress in cDNA and genome DNA analyses has brought the discovery of numerous genes encoding ligand-unknown "orphan" 7TMRs. We have developed a strategy to identify the ligands of orphan 7TMRs by monitoring specific signal transductions induced in cells expressing orphan 7TMRs. Employing this method, we succeeded in identifying the natural ligands of the orphan 7TMRs, hGR3, and APJ. The ligand peptide identified for hGR3 was found to show a specific prolactin release promoting activity in rat anterior pituitary cells in in vitro culture and was therefore named "prolactin-releasing peptide." We named another novel bioactive peptide "apelin," for "APJ endogenous ligand." Although the biological functions of apelin are still under investigation, APJ reportedly acts as a coreceptor in the process of human immunodeficiency virus infection. We believe that the identification of orphan 7TMR ligands will provide clues to reveal the unknown regulatory mechanisms of various physiological phenomena and opportunities for novel drug discovery in the future.

Immunocytochemical localization of prolactin-releasing peptide in the rat brain

A hypothalamic peptide that stimulates PRL release has recently been found as a ligand of an orphan receptor and named PRL-releasing peptide (PrRP). PrRP and its receptor were mainly detected in the hypothalamus and pituitary gland, respectively. Its characteristics suggested PrRP to be a novel hypophysiotropic peptide that stimulates the anterior pituitary PRL cell; however, this remained to be confirmed morphologically. We therefore performed an immunocytochemical study to locate PrRP in the rat brain using the region-specific monoclonal antibodies, P2L-1C and P2L-1T, which recognize the C-terminal and the internal sequence of PrRP, respectively. Our results clearly show that dense immunoreactive nerve fiber networks are present in the paraventricular hypothalamic nucleus, supraoptic nucleus, paratenial thalamic nucleus, basolateral amygdaloid nucleus, and bed nucleus of the stria terminalis. A small number of PrRP nerve fibers was also observed in the neural lobe of the hypophysis. However, no immunopositive fiber was observed in the external region of the median eminence, which is known to be the release site of the classical hypophysiotropic hormones. Also, the distribution of PrRP was not changed during the estrous cycle. We therefore concluded that PrRP probably differs from classical hypothalamic releasing hormones. We found the immunoreactive cell bodies to be mainly in the caudal portion of the dorsomedial hypothalamic nucleus and solitary nucleus. A double immunocytochemical procedure revealed that some PrRP-positive neurons showed synaptic contact with oxytocin-positive cell bodies in the paraventricular hypothalamic nucleus, which suggests that PrRP regulates the function of oxytocin neurons. This is the first report to demonstrate the localization of the novel hypothalamic peptide, PrRP, and we therefore suggest that it takes part in a variety of brain functions. However, it is not yet known how PrRP is transported to the pituitary gland, which is the site that contains the greatest concentration of receptors to this new peptide. Therefore, additional work will be required to resolve this discrepancy between ligand and receptor site location.

Distribution and characterization of immunoreactive prolactin-releasing peptide (PrRP) in rat tissue and plasma

We established a sensitive and specific two-site enzyme immunoassay (EIA) for prolactin-releasing peptide (PrRP) using two region-specific monoclonal antibodies. We investigated the tissue distribution and the plasma concentration of immunoreactive (ir-) PrRP in rats using this assay. Ir-PrRP was widely distributed in the central nervous system and pituitary gland. The highest concentration of ir-PrRP was found in the hypothalamus. In peripheral tissues, appreciable levels of ir-PrRP were found only in the adrenal gland. The mean plasma concentration of ir-PrRP was 0.13 +/- 0.01 fmol/ml (mean +/- SEM). In reverse-phase and gel-filtration high performance liquid chromatography, hypothalamic ir-PrRP eluted at a position identical to that of PrRP31 and PrRP20. On the other hand, ir-PrRP from the adrenal gland and plasma eluted only at the position of synthetic PrRP31, indicating that molecular forms of ir-PrRP in vivo differed among tissues.