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At least 307 records · Page 17Linked to original sources
PubMed1998

The evaluation of 15q proximal duplications by FISH.

Six patients from the clinical cytogenetics laboratory identified as having the normal variant dup(15)(q12) were further evaluated using fluorescence in situ hybridization (FISH). The purpose of this study was to ascertain whether any of the Prader Willi Angelman Chromosome Region (PWCR and ANCR, respectively) loci were duplicated in these patients. The results indicated that the patients could be categorized into two groups. The first group showed no duplication of the PWCR ANCR loci and appeared to belong to the dup(15)(q12) class which is phenotypically silent and is therefore called the normal variant. The second group also showed no duplication of the PWCR/ANCR loci. but had a large alpha satellite variant with D15Z. It is hypothesized that these patients do not have a duplication of 15q12 but rather a centromeric variant which mimics the dup(15)(q12). This study confirms the importance of evaluating apparent variations in the proximal region of chromosome 15 with FISH.

Angelman Syndrome↗
PubMed1982

Transcortin Leuven: a variant of human corticosteroid-binding globulin with decreased cortisol-binding affinity.

Genetic variation of human transcortin was investigated on neuraminidase-treated plasma samples by polyacrylamide gel isoelectric focusing followed by immunofixation of transcortin on cellulose-acetate strips. This procedure was applied systematically to 500 plasma samples obtained from individuals of Caucasian origin. Most samples showed one band focusing at pH 5.52. In three unrelated samples, a two-band pattern was obtained consisting of the normal band (pI 5.52) and a cathodic band of equal color intensity (pI 5.60). Family studies showed that this transcortin variant, which we call transcortin Leuven, is autosomally inherited. In a family of Polish origin two individuals homozygous for transcortin Leuven were found. A striking feature of transcortin Leuven is that it has a 2.6-fold reduced affinity for cortisol at 4 degrees C and a 3.6-fold reduced affinity at 28 degrees C. This lowered affinity is due to an enhanced dissociation rate of the transcortin-cortisol complex. As for normal asialotranscortin, a cortisol-induced charge difference of 0.15 pH unit was observed for this variant.

Female↗
PubMed1987

Expression of human choriogonadotropin-like material correlates with metastatic phenotype of R3230 AC rat adenocarcinoma.

Human choriogonadotropin (hCG)-like material has been found in variable amounts on the surface of cells of human and animal tumors. Intravenous injection of R3230 AC rat adenocarcinoma cells, one of the models investigated, results in multiple lung foci seeding. We analyzed the phenotypic diversity of this tumor by cloning and culturing two distinct cell subpopulations from a cell culture of this tumor, hereafter called OR or original cell culture. One was obtained after repeated exposure of the OR to increasing concentrations of concanavalin A and wheat germ agglutinin. A single clone was isolated and was named lectin-resistant (LR) cell line. The LR cells did not metastasize but maintained stable tumorigenicity and morphology over at least 10 passages. A second cell line was obtained by repeated passage and injection of cells from a single metastatic node. After repeating the process five times, a single clone of cells was selected from the final variant and was called lung metastatic (LM) cell line. The LM cultured cells maintained stable tumorigenicity, morphology, and metastatic properties for no more than 10 passages. OR, LR, and LM cells were assessed by their doubling time (DT), chromosome counts, and hCG immunocytochemistry. The results demonstrated that the LM cell line had a higher chromosome count than the LR and the OR cell lines, and its DT was the shortest. Immunocytochemistry of the transplanted OR neoplasm showed scattered expression of the hCG-like material. By the same techniques a complete lack of reactivity of the LR cells was found. However, almost all cells of the LM line were strongly positive for hCG-like material. After a few passages, the great majority of the LM cells also became unreactive. Our data demonstrate: (i) the existence of marked heterogeneity of the expression of hCG-like material in the primary tumor cell population; (ii) that the expression of hCG-like material correlates with the metastasizing capacity of the cells; and (iii) that there is a phenotypic instability for the expression of hCG-like material by tumor cells when maintained in vitro.

Adenocarcinoma↗
PubMed2001

Differential neonatal imprinting and regulation by estrogen of estrogen receptor subtypes alpha and beta and of the truncated estrogen receptor product (TERP-1) mRNA expression in the male rat pituitary.

Two distinct nuclear estrogen receptors (ERs) have been identified, the classical one, renamed ERalpha, and the more recently cloned ERbeta. In a variety of tissues, gene expression of both receptor subtypes results in the generation of multiple transcripts encoding the full-length as well as several alternately spliced isoforms. In the rat pituitary, a truncated, tissue-specific variant of ERalpha, called TERP-1, has been identified and found able to modulate ERalpha and ERbeta activity. So far, its pattern of expression and hormonal regulation have been mostly studied in females. The present study was designed to analyze the pattern of expression of TERP-1 mRNA in the male rat pituitary at different stages of postnatal development, and to evaluate the impact of neonatal imprinting and estrogen treatment upon TERP-1 expression in the male pituitary. Assessment of TERP-1 mRNA levels by semi-quantitative RT-PCR, using a variant-specific primer pair, revealed that TERP-1 is also expressed in the male rat pituitary. Relative mRNA expression levels changed markedly during postnatal development, with moderate expression of the TERP-1 transcript at birth, barely detectable levels during the infantile-prepubertal period, and maximal values in adulthood. Expression of TERP-1 was sensitive to neonatal estrogen exposure, which resulted in a significant, persistent increase in mRNA levels from the infantile period until puberty. This phenomenon was not mimicked by neonatal blockade of endogenous GnRH. In addition, estrogen was able to acutely up-regulate pituitary TERP-1 mRNA expression levels in prepubertal (30-day-old) and adult (75-day-old) males. Interestingly, neonatal imprinting as well as acute estrogen treatment resulted in opposite effects on TERP-1 and full-length ERalpha and ERbeta transcripts, the latter being decreased under both conditions. In conclusion, our data indicate that TERP-1 mRNA is expressed in a developmentally regulated manner in the male rat pituitary, and is affected by neonatal estrogen imprinting and acute estrogen treatment. Regulation of TERP-1 expression by neonatal or acute estrogen treatment may thus represent an additional tuning mechanism for estrogen actions in the male rat pituitary.

Aging↗
PubMed1998

Identification of estrogen receptor beta2, a functional variant of estrogen receptor beta expressed in normal rat tissues.

The effects of estrogen and estrogen agonists can be mediated by estrogen receptor alpha (ER alpha) and estrogen receptor beta (ER beta). We now report the identification and initial characterization of several novel isoforms of rat ER beta messenger RNA (mRNA). The most abundant of these mRNA variants we have called ER beta2. ER beta2 had an in-frame insertion of 54 nucleotides that resulted in the predicted insertion of 18 amino acids within the ligand binding domain. We demonstrated by semiquantitative RT-PCR and RNase protection that ER beta2 mRNA was expressed at levels equal to those of the previously published ER beta (ER beta1) in ovary, prostate, pituitary, and muscle. In tissues of the nervous system, including frontal cortex, hippocampus, and hypothalamus, ER beta1 was present in a 2- to 6-fold greater abundance than ER beta2. We have also detected variants of both ER beta1 and ER beta2 mRNAs that contained deletions of 117 bp encompassing the region encoding the second zinc finger of the DNA binding domain. All four mRNA species were efficiently translated into functional protein in a heterologous system. ER beta2 bound estradiol with a lower affinity (Kd 5.1 nM) than either ER alpha (0.19 nM) or ER beta1 (0.14 nM). The binding of ER beta2 was selective in that cortisol, testosterone, aldosterone, and progesterone among other agents did not compete for estradiol binding. However, a variety of known estrogenic agents, including physiological estrogens (estrone and estriol), plant and environmental estrogens (genistein, coumestrol, bisphenol A, methoxychlor), and pharmocological agents (tamoxifen, 4-hydroxytamoxifen) did effectively compete for estradiol binding to both ER beta1 and ER beta2. Interestingly, the binding pharmacology differed among the agents tested. For example, genistein competed effectively for estradiol binding to ER beta1 but was > 150-fold weaker at competing from ER beta2. In contrast, 4-hydroxytamoxifen competed equally well at both receptors. We have also demonstrated by a gel shift assay that both ER beta1 and ER beta2 bound specifically to DNA containing a consensus estrogen response element. ER beta1 and ER beta2 could heterodimerize with each other and with ER alpha. Both ER beta1 and ER beta2 activated transcription in response to estradiol, however, ER beta2 required a 1000-fold greater estradiol concentration for activity than did ER beta1. Cotransfection of ER beta2 had no effect on ER beta1 activation when used in a equal ratio. A 10-fold excess of ER beta2 did raise the half-maximal dose of estradiol required for transcriptional activation, whereas the maximal level of induction did not change. The ER beta complementary DNAs deleted within the DNA binding domain could not bind to DNA or activate transcription from this reporter in the cell backgrounds tested. In conclusion, although the physiological significance of these ER beta variants warrants further investigation, ER beta2 mRNA encodes a specific, functional receptor for estradiol and estrogenic agents. We propose that ER beta2 should also be considered in addition to ER beta1 and ER alpha when describing the effects of estrogen, estrogen agonists/antagonists, or environmental estrogens.

Amino Acid Sequence↗
PubMed2001

The classification, genetics and neuropathology of frontotemporal dementia. Introduction to the special topic papers: Part I.

Interest in the neuropsychology and neuropsychiatry of frontotemporal dementia (FTD) has escalated in the past decade, as evidenced by the accompanying 10 special topic papers from research groups in the UK, France, North America and Australia addressing a wide range of theoretical and clinical issues. The first part of this review deals with the confusing terminologies that have been used in the area and argues for the retention of the term FTD as the general clinical label, with further subcategorization into the three principal clinical syndromes seen at presentation: frontal variant FTD (often called dementia of frontal type), semantic dementia and progressive non-fluent aphasia. Each of these syndromes has a characteristic profile of presenting clinical features, but may be accompanied by any one of five types of non-Alzheimer pathological change. There have also been significant advances in the genetics of FTD with the identification of tau gene mutations on chromosome 17 in some familial cases. The remarkable story of the discovery of these, the tau gene mutations, is briefly described. Part II of this review (Hodges and Miller, 2001) sets the special issue papers within the context of advances in the neuropsychology of frontal variant FTD and semantic dementia.

Dementia↗
PubMed1996

Multiple features of advanced melanoma recapitulated in tumorigenic variants of early stage (radial growth phase) human melanoma cell lines: evidence for a dominant phenotype.

The vast majority of primary human cutaneous melanomas undergo a slow and gradual progression from a clinically indolent, curable radial growth phase (RGP) to a malignant vertical growth phase. We sought to develop a way of isolating genetically related malignant variants from a benign RGP human melanoma, called WM35. The parent and variants were then used as a model system to examine to what extent the expression of clinically and biologically relevant phenotypic features characteristic of advanced melanomas are associated with (and thus perhaps causative of) such a malignant conversion. Such a model system could also be used as a means of eventually identifying genetic alterations and cellular changes involved in the malignant switch in melanoma progression. To develop such a model, we subjected WM35 cells to retroviral insertional mutagenesis, which was followed by selection for progressive growth of solid tumors in nude mice. Highly aggressive and phenotypically stable tumorigenic variants were derived which contained at least four integrated proviruses. In contrast to the parental WM35 cells, these cell lines expressed several phenotypic features characteristic of naturally derived, advanced-stage malignant melanoma cells. Thus, in addition to tumor-forming ability in nude mice, the variants were growth factor and anchorage independent, overexpressed the MUC18 adhesion molecule, and lost responsiveness to the growth-inhibitory effect of several cytokines, including interleukin 6, transforming growth factor beta, interleukin 1beta, and tumor necrosis factor-alpha. Tumorigenicity and "multicytokine resistance" were dominant traits since in somatic cell hybrids between the parental cells and a tumorigenic subline no suppressive effect of the former cell population was observed. These findings suggest that one or more dominantly acting genetic alterations might be involved in this progression of RGP melanoma cells. The identity of such alterations remains to be determined.

Animals↗
PubMed2003

Production of cytolethal distending toxins by pathogenic Escherichia coli strains isolated from human and animal sources: establishment of the existence of a new cdt variant (Type IV).

Three types of cytolethal distending toxin (CDT), namely, CDT-I, CDT-II, and CDT-III, have been described in Escherichia coli. Using primers designed for the detection of sequences common to the cdtB genes, we analyzed by PCR a set of 21 CDT-producing E. coli strains of intestinal and extraintestinal origins isolated from human and different animal species in several European countries and in the United States. On the basis of the existing differences in the cdtB genes, cdt-I-, cdt-II-, and cdt-III-specific primer pairs were designed and used for cdt typing. These new primers successfully differentiated all of the previously described cdt genes. Six strains proved to be cdt-I; eight strains proved to be cdt-III. However, none of the type I-, II-, and III-specific primers generated amplicons from six CDT(+) strains, suggesting the existence of a new cdt variant. Sequence analysis of the amplicons from two untypeable genes confirmed the existence of a new cdt variant that we called cdt-IV. Using the new specific primers, cdt-IV was detected in human, porcine, and poultry strains of intestinal and extraintestinal origins. To validate all sets of cdt specific primers, a group of 353 human E. coli strains isolated in Hungary was then investigated for the presence of cdt genes. This included 190 strains isolated from patients with urinary tract infections (UTI), 51 strains isolated from other (nonurinary) extraintestinal infections, and 112 intestinal strains isolated from healthy individuals. Of 190 UTI strains, 15 (7.9%) had cdt genes. Of 51 non-UTI extraintestinal strains 3 (5.9%) contained the cdt gene, and 1 (0.9%) of 112 healthy intestinal strains was PCR positive. Five strains proved to be cdt-I, and fourteen strains proved to be cdt-IV. The CDT-producing extraintestinal strains belonged to a wide variety of serogroups, including O2, O6, O75, and O170. In conclusion, we have developed a new PCR typing system for CDT able to detect a new CDT variant present in pathogenic E. coli strains obtained from animals and humans.

Animals↗
PubMed1983

Candidate adenoviruses 40 and 41: fastidious adenoviruses from human infant stool.

About 200 antigenically related adenoviruses were isolated from cases of infantile diarrhoea in the Netherlands and North-West Germany. The viruses were fastidious and failed to replicate serially in human diploid fibroblasts and in primary human embryonic kidney cells. A number of strains were established in HeLa, HEp-2, Graham (293), cynomolgus monkey kidney, and Chang conjunctival cells. The viruses were mammalian adenoviruses by the usual criteria. No relationship to the 39 known human adenovirus species was found, either by neutralization tests or by haemagglutination inhibition tests. Neutralization tests showed two distinct variants, represented by strains Tak and Dugan. The variants were identical in haemagglutination inhibition tests. DNA restriction enzyme analysis showed Tak and Dugan to have considerably different genomes, indicating that these variants should be classified as different species (Wadell et al, 1983). It is proposed that the variants should be called Mastadenovirus h 40 (with reference strains Dugan and Hovi X) and Mastadenovirus h 41 (with reference strain Tak). Neutralization and haemagglutination inhibition tests demonstrated that the viruses from Glasgow and Helsinki (Hovi X) described by Johansson et al [1980] and by Kidd and Madeley [1981] belong to these two adenovirus species.

Adenoviridae Infections↗
PubMed2000

NABC1 (BCAS1): alternative splicing and downregulation in colorectal tumors.

We have identified a new splicing variant of the gene "novel amplified in breast cancer 1," NABC1 (HGMW-approved symbol BCAS1). This variant, which we call NABC1_5B, uses a previously unidentified 135-bp exon. Also in this report, we confirm that NABC1 is overexpressed in breast tumors and show that both NABC1 and NABC1_5B are downregulated in colorectal tumors.

Alternative Splicing↗
PubMed1994

No strategy is evolutionarily stable in the repeated prisoner's dilemma.

Following the influential work of Axelrod, the repeated Prisoner's Dilemma game has become the theoretical gold standard for understanding the evolution of co-operative behavior among unrelated individuals. Using the game, several authors have found that a reciprocal strategy known as Tit for Tat (TFT) has done quite well in a wide range of environments. TFT strategists start out co-operating and then do what the other player did on the previous move. Despite the success of TFT and similar strategies in experimental studies of the game, Boyd & Lorberbaum (1987, Nature, Lond. 327, 58) have shown that no pure strategy, including TFT, is evolutionarily stable in the sense that each can be invaded by the joint effect of two invading strategies when long-term interaction occurs in the repeated game and future moves are discounted. Farrell & Ware (1989, Theor. Popul. Biol. 36, 161) have since extended these results to include finite mixes of pure strategies as well. Here, it is proven that no strategy is evolutionarily stable when long-term relationships are maintained in the repeated Prisoner's Dilemma and future moves are discounted. Namely, it is shown each completely probabilistic strategy (i.e. one that both co-operates and defects with positive probability after every sequence of behavior) may be invaded by a single deviant strategy. This completes the proof started by Boyd and Lorberbaum and extended by Farrell and Ware. This paper goes on to prove that no reactive strategy with a memory restricted to the opponent's preceding move is evolutionarily stable when there is no discounting of future moves. This is true despite the success of a more forgiving variant of TFT called GTFT in a recent tournament among reactive strategies conducted by Nowak & Sigmund (1992, Nature 355, 250) where future moves were not discounted. GTFT, for example, may be invaded by a pair of reactive mutants. Since no strategy is evolutionarily stable when future moves are discounted in the repeated game, the restriction of strategy types to those actually maintained by mutation and phenotypic and environmental variability in natural populations may be the key to understanding the evolution of co-operation. However, the result presented here that the somewhat realistic reactive strategies are also not evolutionarily stable at least in the non-discounted game suggests something else may be going on. For one, the proof that no reactive strategy is evolutionarily stable ironically shows the robustness of TFT-like strategies.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

A novel case of compound heterozygosity with "Normandy"/type I von Willebrand disease (vWD). Direct demonstration of the segregation of one allele with a defective expression at the mRNA level causing type I vWD.

We report the case of a family with type I von Willebrand disease (vWD), characterized by a quantitative defect in von Willebrand factor (vWF), associated with a defective binding of vWF to factor VIII (FVIII) also called the "Normandy" variant of vWD. PCR products from genomic DNA of the family members were analysed in the region coding for the binding domain of vWF to FVIII. It showed that the proposita and one of her sons were heterozygous for the Arg91Gln missense mutation, abolishing an MspI restriction enzyme site located in exon 20. The transcription of the normal and mutated alleles was tested by the amplification of cDNA after reverse transcription of platelet mRNA in this region. A total lack of expression of the normal allele was observed in the proposita, who appeared as a compound heterozygous with one allele mutated at Arg91 and a "silent" expression of the other one. The segregation of the "silent" allele was studied in the family with the exonic BstEII RFLP both at the DNA and mRNA levels. The proposita has transmitted her "silent" allele to her daughter and to another son. As this son was informative for this RFLP, the absence of expression of the allele could be demonstrated at the mRNA level, providing evidence that this defect was responsible for his type I vWD.

Alleles↗
PubMed1990

1.3E2, a variant of the B lymphoma 70Z/3, defective in activation of NF-kappa B and OTF-2.

The mouse B-cell cell lymphoma 70Z/3 is a convenient model system in which to study the regulation of immunoglobulin synthesis. Three transcriptional activators of kappa (kappa) light chain synthesis have been identified for these cells: bacterial lipopolysaccharide (LPS), interferon-gamma (IFN), and interleukin-1 (IL-1). The response of the kappa gene in 70Z/3 cells to LPS is mediated by increases in two transcription factors: NF-kappa B and OTF-2. In contrast, IFN has no effect on either of these factors in 70Z/3 cells. We have isolated by immunoselection an LPS- IFN+ variant of 70Z/3 called 1.3E2. We show here that LPS treatment of these cells causes no increase in nuclear localization of either NF-kappa B or OTF-2. Although they have normal levels of cytoplasmic NF-kappa B, it cannot be activated by LPS or by phorbol 12-myristate 13-acetate (PMA) treatment of the cells. These experiments expand the genetic dissection of the molecular pathways of activation of kappa transcription in 70Z/3 cells.

Animals↗
PubMed1988

Hemoglobin types in Saanen goats and Barbary sheep: genetic and comparative aspects.

By the use of the Immobiline technique at pH ranges 7.0-7.6 and 6.9-7.9, 16 different hemoglobin (Hb) phenotypes were observed in 61 English Saanen goats. They are explained in this breed by a genetic theory of five beta-globin genes (A4, A6, A8, E, and D) and two closely linked alpha-globin loci ('alpha and "alpha) of which the "alpha has a variant allele, provisionally called "alpha X. Family data together with observed and expected Hb frequencies were in agreement with the genetic theory. Among six Barbary sheep there were three Hb phenotypes explained by the occurrence of the beta-chain alleles B and Cna.

Alleles↗
PubMed1993

Growth advantage ("clonal dominance") of metastatically competent tumor cell variants expressed under selective two- or three-dimensional tissue culture conditions.

In previous experiments it was shown that injection into syngeneic CBA/J mice of cell mixtures containing an excess of non-metastatic SP1 mouse mammary carcinoma cells with a ras transfected metastatic variant of SP1 called C1, always resulted in the eventual dominance of the C1 subpopulation at the site of inoculation. This occurred despite the growth rates of the two cell populations being identical in vivo when grown separately. The means by which the C1 subpopulation achieved "clonal dominance" is thought to involve its responsiveness to stimulatory paracrine growth factors liberated by the non-metastatic SP1 population. The clonal dominance process, however, could not be recapitulated in conventional monolayer tissue culture conditions in which SP1 and C1 cells were grown together in high concentrations of serum, i.e. under non-limiting culture conditions. We now show that clonal dominance of C1 cells can be observed when the cell mixture is maintained in tissue culture for extended periods, or when the cells are grown under selective, limiting conditions, some of which may mimic growth conditions in vivo more accurately. These conditions were a) growth in low (limiting) serum concentrations; and b) growth as three-dimensional multicellular aggregates, i.e. as "tumor spheroids". Under all of these conditions dominance of the C1 subpopulation always took place, but with an efficiency 6- to 40-fold less than generally observed in vivo. C1 cells were also able to form more stable (compact) spheroids compared to SP1 cells. Entrapment of the latter in mixed C1/SP1 spheroids increased the recovery of the SP1 cells suggesting some kind of "rescue" mechanism in which cells are protected from physical forces by three-dimensional structure. The relevance of these in vitro interactions for clonal dominance in primary tumors and metastasis in vivo are discussed.

Adenocarcinoma↗
PubMed1986

Ulnar variance in Kienböck's disease.

Forty four patients with forty seven wrists suffering from Kienböck's disease were re-examined. The mean observation time was 20.5 years. In all forty seven wrists the treatment had been immobilization. Using a standard X-ray projection, and a reliable method of ulnar variance measuring, the ulnar variance was determined by three observers independently. Comparing the result with the ulnar variance in normal wrists we found the so-called "ulnar minus variant" overrepresented in patients with Kienböck's disease. However, comparing X-rays taken at the time of diagnosis with X-rays at re-examination, we found in eight out of forty seven wrists that a subchondral bone formation in the distal radium opposite the lunate bone had taken place. This bone formation will tend to enhance the negative value of ulnar variance measurements, and suggests an explanation of the overrepresentation of "ulnar minus variants" in Kienböck's disease. Excluding these eight wrists from the material and comparing the mean ulnar variance value in the remaining thirty nine wrists with the mean value in normal wrists no statistical difference was shown. Based on these observations it seems unlikely that the "ulnar minus variant" has any bearing on the cause of Kienböck's disease.

Adolescent↗
PubMed1987

Kienböck's disease--the influence of arthrosis on ulnar variance measurements.

The individual difference in ulnar variance measurements between diseased and unaffected wrists in 38 patients with unilateral Kienböck's disease was determined and related to the degree of arthrosis in the affected wrists. In patients without arthrosis there was no difference in measurements. With increasing arthrosis there was a progressive increase of patients with individual difference in ulnar variance measurements: up to 50% in those with severe arthrosis. Where a difference in ulnar variance was encountered, the wrist with Kienböck's disease represented the more negative value in 90%. It is concluded that over-representation of the so-called "ulnar minus variant" in Kienböck's disease is based on osteo-arthritic changes in the wrist, resulting in a pseudo-lengthening of the distal radius, and that this is therefore a consequence of the disease. The "ulnar minus variant" seems to have no bearing on the cause of Kienböck's disease.

Adult↗
PubMed1997

Distribution of [Leu31,Pro34]NPY-sensitive, BIBP3226-insensitive [125I]PYY(3-36) binding sites in rat brain: possible relationship to Y5 NPY receptors.

Recently, using molecular cloning approaches, three new neuropeptide Y (NPY)/peptide YY (PYY) receptors have been described in rodent brain, with pharmacological profiles that differ from the three previously described Y1, Y2 and Y3 NPY receptors and the Y4 pancreatic polypeptide- (PP-) preferring receptor. Two of these new receptors are spice variants and are called Y5 receptors, whilst a third receptor has been called Y6 and has been suggested to be expressed only in the mouse. In the absence of a totally selective Y5 and/or Y6 radioligands, we have examined [125I]PYY(3-36) binding, which binds Y2 and Y5/Y6 receptors, using homogenate assays and quantitative receptor autoradiography to study the distribution of the three newly discovered Y5/Y6 receptors by masking binding to Y1 receptors with high concentrations of the non-peptidergic selective Y1 antagonist, BIBP3226, and using either [Leu31,Pro34]NPY or human PP to mask binding to Y5 and Y6 receptors, leaving binding to Y2 receptors. Using this approach, [125I]PYY(3-36) labels a small population of Y1 receptors and a larger population of binding sites that are insensitive to BIBP3226, human PP and [Leu31,Pro34]NPY, presumed to be Y2 receptors. There was also [125I]PYY(3-36) binding to sites sensitive to NPY, human PP and [Leu31,Pro34]NPY, but insensitive to BIBP3226, located in the hypothalamus, amygdala, hippocampus and thalamus. As one of the recently cloned Y5 receptors is synthesized in these regions, as shown by in-situ hybridization techniques, we suggest that the small population of [125I]PYY(3-36) binding sites which are sensitive to human PP and [Leu31,Pro34]NPY, but insensitive to BIBP3226, may represent binding to Y5 receptors. We have been unable, however, to visualize a smaller population of Y6 receptors which are labelled by [125I]PYY3-36 and sensitive to [Leu31,Pro34]NPY, but not to BIBP3226 and human PP, confirming that the murine Y6 receptor does not appear to be expressed in rat brain.

Animals↗