Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BUTYRATES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources
PubMed1995

Comparison of the effect of hydrocortisone, hydrocortisone-17-butyrate and betamethasone on collagen synthesis in human skin in vivo.

It has been shown previously that topical corticosteroid treatment decreases collagen synthesis in human skin in vivo and that the adverse effects are due to reduced collagen synthesis. The aim of the present study was to evaluate the effect of hydrocortisone, hydrocortisone-17-butyrate and betamethasone on collagen synthesis in human skin in vivo. Fourteen healthy male volunteers applied hydrocortisone, hydrocortisone-17-butyrate, betamethasone and vehicle twice a day for one week to four separate areas marked on their abdominal skin. The collagen synthesis rate in the skin was measured by assaying collagen propeptides from the suction blisters induced on the treated areas. Aminoterminal propeptide of type I procollagen (PINP) and aminoterminal propeptide of type III procollagen (PIIINP) were measured from skin blister fluid using radioimmunoassays. Skin thickness was measured with ultrasound. Hydrocortisone decreased the two propeptides studied in the suction blister fluids less than did hydrocortisone-17-butyrate and betamethasone, but the interindividual variation was great. Hydrocortisone-17-butyrate and betamethasone had almost similar decreasing effects on the propeptides in the suction blister fluid. Hydrocortisone decreased the concentrations of PINP and PIIINP by about 35%. In some subjects (4/14) the decline of the collagen propeptide levels was over 50%. The decline in the concentration of PINP was 63% by hydrocortisone-17-butyrate and 69% by betamethasone, while the decrease in PIIINP was 55% by hydrocortisone-17-butyrate and 62% by betamethasone. None of the treatments had any effect on skin thickness within one week. In conclusion, it seems that hydrocortisone is less atrophogenic than hydrocortisone-17-butyrate and betamethasone, as shown by radioimmunoassays for collagen propeptides. The order of inhibitory potency of the three glucocorticoids on collagen synthesis was hydrocortisone < hydrocortisone-17-butyrate < betamethasone. Thus, assay of collagen propeptides from suction blisters can be used to screen various steroids with respect to their action on collagen synthesis.

Administration, Topical↗
PubMed1981

Clobetasone butyrate eye drops. Effect on ocular inflammation and intraocular pressure.

Clobetasone butyrate eye drops comprise a new steroid preparation which has been investigated in two comparable, double-blind, multicentre clinical trials in patients with ocular inflammation. One study compared clobetasone butyrate with betamethasone phosphate eye drops (205 patients) and the other study compared corresponding preparations containing neomycin (169 patients). There was no difference between the responses to clobetasone butyrate and betamethasone. An excellent or good response was obtained in 73 per cent of patients treated with clobetasone butyrate, 75 per cent with betamethasone, 69 per cent with clobetasone butyrate formulated with neomycin, and 76 per cent with betamethasone formulated with neomycin. Patients who were known to react with a rise of intraocular pressure (IOP) to steroids were treated with clobetasone butyrate eye drops in one eye and either prednisolone eye drops (6 patients) or hydrocortisone eye drops (4 patients) in the other eye. The doses were continued for 6 weeks, or less if the IOP rose more than 10 mm Hg in one eye. All patients experienced a greater intraocular pressure rise in the eye treated with prednisolone or hydrocortisone. The mean changes in IOP were 9 mm Hg for prednisolone compared to 2 mm Hg for clobetasone butyrate (P less than 0.05 Wilcoxon signed ranks test) and 16 mm Hg for hydrocortisone compared to 2 mm Hg for clobetasone butyrate.

Adolescent↗
PubMed1988

Sodium butyrate preserves aspects of the differentiated phenotype of normal adult rat hepatocytes in culture.

We have determined that sodium butyrate and, to a lesser extent, dimethylsulfoxide (DMSO) and 3-aminobenzamide (3-AB) preserve aspects of the differentiated phenotype of primary cultures of adult rat hepatocytes. The histone deacetylase inhibitor, butyrate, inhibits the increase in gamma-glutamyltranspeptidase (GGT) activity and the decrease in basal tyrosine aminotransferase (TAT) activity normally observed when hepatocytes are cultured under appropriate conditions. The effects of butyrate on GGT and TAT activities are accompanied by parallel changes in GGT and TAT mRNA levels. The poly(ADP)ribose-synthetase inhibitor, 3-aminobenzamide, has effects similar to butyrate on GGT activity and mRNA levels, while both 3-AB and DMSO increase basal TAT activity in cultured hepatocytes. Under appropriate conditions all three agents--butyrate, 3-AB, and DMSO--extend the length of time cultured hepatocytes can be maintained as confluent monolayers. However, under all the conditions studied, butyrate extended the length of time hepatocytes could be maintained as monolayers more than any other treatment used. Butyrate-treated hepatocytes maintained ultrastructural features that were more similar to those of hepatocytes in vivo than hepatocytes treated with any other of the agents tested. Histone acetylation levels of primary cultures of adult rat hepatocytes declined concomitant with the loss of the differentiated phenotype of the cells. These results suggest that histone acetylation may play a role in the changes in gene expression observed when hepatocytes are placed in culture.

Animals↗
PubMed1988

Effects of 5-azacytidine, sodium butyrate, and phorbol esters on amino acid transport system A in a kidney epithelial cell line, MDCK: evidence for multiple mechanisms of regulation.

Neutral amino acid transport by system A was investigated in the epithelial cell lines MDCK and MDCK-T1. The latter line is a chemically induced, oncogenically transformed line derived from MDCK. Inducers of differentiation, sodium butyrate and 5-azacytidine, and a tumor promoter, TPA, were used as probes to delineate pathways of regulation involved in system A response to a variety of physiological conditions and agents. Azacytidine, an inhibitor of DNA methylation, and butyrate, an enhancer of histone acetylation, inhibited expression of system A, had little effect on system ASC, and slightly stimulated system L. Inhibition of system A expression by butyrate and azacytidine occurred under different conditions. Increases in system A activity due to amino acid starvation or transformation were inhibited by butyrate but not by azacytidine. Repressed system A activity, normally observed in the presence of high levels of amino acids, was more sensitive to azacytidine than to butyrate. The tumor promoter, TPA, stimulated system A activity in MDCK cells under normal growth conditions but did not stimulate activity in amino acid-starved MDCK cells or in MDCK-T1 cells. Stimulation of system A activity by TPA was prevented by prior exposure to butyrate but not to azacytidine. These results suggest 1) that system A expression observed in growing amino-acid-repressed MDCK cells is modulated by an azacytidine-sensitive mechanism and 2) that the elevated expression of system A activity induced by amino acid starvation, by chemical transformation to MDCK-T1, and by TPA is modulated by a butyrate-sensitive mechanism.

Amino Acids↗
PubMed1989

Butyric acid causes morphological changes in cultured chondrocytes through alterations in the extracellular matrix.

Butyric acid induces characteristic changes in the morphology of chick embryo chondrocytes. Chick embryo chondrocytes when cultured in the absence of butyrate exhibit a spherical morphology and synthesize cartilage-specific chondroitin sulfate proteoglycan (CSPG). When these cultures are initiated and maintained in the presence of butyric acid, chondrocytes exhibit a mesenchymal morphology, a 90% reduction in the synthesis of CSPG, and a 75% reduction in DNA synthesis. The reduced synthesis of CSPG and DNA was shown not to be dependent on the morphological change. Chondrocytes require CSPG in order to express a spherical morphology, since including chondroitinase ABC in the culture media caused the cells to spread. In addition, the treatment of chondrocytes with purified CSPG prior to culture in media containing butyric acid resulted in spherical cells. The butyrate-induced spreading was shown to require either serum or fibronectin and could be prevented with antiserum against chick cell-surface fibronectin (cFn). Cell-surface fibronectin, which was present on both spherical and flattened chondrocytes, organized into fibrils beneath cells which spread. Increased fibronectin synthesis was not responsible for the butyrate-induced morphological change. From this evidence, it is concluded that the mechanism by which butyrate alters the morphology of these cells in culture involves inhibiting CSPG synthesis, thus preventing CSPG accumulation in the extracellular matrix (ECM). The absence of CSPG in the ECM allows fibronectin to mediate spreading of chondrocytes in culture.

Animals↗
PubMed1990

Regulation of thyroid hormone receptor and c-erbA mRNA levels by butyrate in neuroblastoma (N2A) and glioma (C6) cells.

Butyrate produced a biphasic modulation of the thyroid hormone receptor in neuroblastoma N2A cells increasing receptor number by 20-35% at concentrations 0.25-0.75 mM and decreasing receptor levels by 30-55% at 2-4 mM. The half-life of the receptor, as assessed by its disappearance after incubation with 18 microM cycloheximide was 8.4 hr in control cells and 10.3 hr and 5.0 hr in cells incubated with 0.25 and 4 mM butyrate, respectively. This compound increased the abundance of multyacetylated forms of histone H4 from 30% in control cells to almost 70% with butyrate 4 mM. In glioma C6 cells, the fatty acid produced a dose-dependent increase of receptor levels (up to 3-4-fold with 2-5 mM butyrate) and had little effect in increasing multiacetylation (from 30% in controls to 42-46% with 2-5 mM butyrate). Recent studies have shown that the c-erbA proto-oncogen codes for the thyroid hormone receptor. In N2A and C6 cells, 2 c-erbA-related mRNAs, one measuring 2.6 kb and the other 6 kb, were detected. Both forms were differently regulated by butyrate. This compound decreased the abundance of the 2.6 kb forms in both cell types, even at the concentrations at which there was an elevation of receptor levels. Only the largest mRNA correlated with receptor concentration increasing by 2-3-fold after treatment of C6 cells with butyrate, and undergoing a smaller but biphasic change in N2A cells. Our data suggest that modification of chromatin structure probably secondary to acetylation induces changes in thyroid hormone receptor levels in neuroblastoma and glioma cells by affecting both receptor stability and receptor mRNA levels.

Animals↗
PubMed1994

Selective hypermethylation of transcribed nucleosomal DNA by sodium butyrate.

Previous studies have shown that treatment of cultured fibroblasts with millimolar concentrations of sodium butyrate results in increased methylation of cytosine residues in DNA. In this study, active nucleosomes were fractionated from the inactive ones by organomercurial agarose column chromatography. DNA in each fraction was hydrolyzed to its constituent bases and subjected to HPLC analysis in order to determine the 5-methylcytosine content. In control cells, the active nucleosomal DNA was hypomethylated (0.97 +/- 0.27% 5-methyleytosine) when compared with the inactive DNA fraction (1.61 +/- 0.15%). This result was not unexpected since DNA hypermethylation is generally associated with gene inactivation. Treatment of cells with sodium butyrate, however, resulted in increased methylation of the active nucleosomal DNA such that it was comparable to that of the inactive fraction of control cells (1.73 +/- 0.02% 5-methylcytosine). A much smaller increase in 5-methylcytosine content was detected in the inactive DNA fraction of sodium butyrate-treated cells (from 1.61 to 1.89%). Removal of the sodium butyrate followed by a chase in butyrate-free medium for up to 120 h failed to reverse the butyrate-induced hypermethylation. Reversal was achieved only after continuous culture in butyrate-free medium for 10 days.

Butyrates↗
PubMed1996

Butyrate and the colonocyte. Implications for neoplasia.

Butyrate is produced in the colon of mammals as a result of microbial fermentation of dietary fiber, undigested starch, and proteins. Butyrate may be an important protective agent in colonic carcinogenesis. Trophic effects on normal colonocytes in vitro and in vivo are induced by butyrate. In contrast, butyrate arrests the growth of neoplastic colonocytes and inhibits the preneoplastic hyperproliferation induced by some tumour promoters in vitro. We speculate that selective effects on G-protein activation may explain this paradox of butyrate's effects in normal versus neoplastic colonocytes. Butyrate induces differentiation of colon cancer cell lines. It also regulates the expression of molecules involved in colonocyte growth and adhesion and inhibits the expression of several protooncogenes relevant to colorectal carcinogenesis. Additional studies are needed to evaluate butyrate's antineoplastic effects in vivo and to understand its mechanism(s) of action.

Animals↗
PubMed1985

Sodium butyrate induced alterations in lysosomal enzyme activity.

Treatment of cultured HeLa cells with 5 mM sodium butyrate causes an inhibition of growth as well as extensive chemical and morphological differentiation. Lysosomal enzyme activity changes have been associated with both normal and neoplastic growth as well as many aspects of the neoplastic process. The comparative ultrastructural results show that the butyrate-treated cells have a more extensive internal membranous system than the untreated cells, whereas other organelles seem unaffected by the butyrate treatment. Methods for the histochemical localization of lysosomal acid phosphatase show a twofold increase in particulate reaction product in the butyrate-treated HeLa cells. Isolation of lysosomes followed by a comparative enzyme analysis shows a two to three fold increase in acid phosphatase activity per cell after 24 h of butyrate treatment, as well as three to four fold increase in beta-glucuronidase activity. These increases reverse within 24 h of removal of the butyrate from the culture medium. These results as interpreted suggest that butyrate treatment may be preventing sublethal autolysis by arresting the leakage of the lysosomal enzymes from the lysosome into the cytosol and thus allowing the cell to chemically and morphologically differentiate.

Acid Phosphatase↗
PubMed1987

Effect of sodium butyrate on primary cultures of adult rat hepatocytes.

Sodium butyrate, at millimolar concentrations, seems to mediate or initiate multiple effects on many mammalian cells in culture. Although many transformed cell lines respond to butyrate treatment with acquisition of normal cellular characteristics, the effect of butyrate on a normal cell type, the parenchymal hepatocyte, has not been studied. Serum-free primary cultures of adult rat hepatocytes maintain many adult characteristics, yet after several days in culture a loss of adult characteristics occurs while fetal characteristics are often reexpressed. Therefore, we investigated whether butyrate treatment would improve the morphologic and biochemical characteristics of cultured hepatocytes. Exposure to 5 mM butyrate for 3 d did not affect hepatocyte viability or morphology but retarded the progressive decline in cytochrome P-450 levels and 5'-nucleotidase activity. The spontaneous increase in alkaline phosphatase activity was reduced and the induction of tyrosine aminotransferase was inhibited after 3 d in culture. The fetal liver characteristic, gamma glutamyltranspeptidase, was not affected by butyrate treatment. Results of this study suggest that butyrate represents a nontoxic compound capable of improving the maintenance of cell culture characteristics of adult rat hepatocytes.

5'-Nucleotidase↗
PubMed1990

The differentiation-inducing agent sodium butyrate produces divergent effects on albumin and thyroxine-binding globulin synthesis by human hepatoblastoma-derived (Hep G2) cells.

The addition of sodium butyrate, a differentiation-inducing agent, to the culture medium of human hepatoblastoma-derived (Hep G2) cells, produced a dose-dependent and time-dependent increase in albumin (ALB) and decrease in T4-binding globulin (TBG) synthesis and secretion. In the presence of 0.01 to 2.0 mM sodium butyrate, newly synthesized [35S]ALB progressively increased up to 139% of control cultures grown in the absence of sodium butyrate, whereas TBG synthesis was already slightly inhibited using the lowest concentrations of this agent and further diminished thereafter. The use of 5 mM and 10 mM sodium butyrate inhibited the synthesis of both proteins, probably as a consequence of toxic effects on cell cultures. The addition of 1 mM sodium butyrate for variable time intervals caused an increase in the amount of ALB recovered in the medium up to 146% after 72 h, and a decrease of TBG up to 44% of controls. These different effects on ALB and TBG occurred concomitantly with an inhibition of cell growth, as shown by the reduction in the cell number/flask compared to control cultures. At the highest sodium butyrate concentrations, a relevant impairment in the secretion of newly synthesized TBG, but not of ALB, also occurred. These divergent effects on ALB and TBG synthesis by Hep G2 cells might be related to biochemical differentiation induced by sodium butyrate in this tumoral cell system, suggesting that TBG synthesis is increased in Hep G2 cells because of their neoplastic nature.

Albumins↗
PubMed1989

Butyrate increases catalase activity and protects rat pulmonary artery smooth muscle cells against hyperoxia.

A protective effect of butyrate against hyperoxia was found with adult rat pulmonary artery smooth muscle cells. Butyrate (5mM) when added just prior to the hyperoxic exposure (95%) markedly decreased lactate dehydrogenase release from cells during 68 hours of exposure (22% release with butyrate versus 98% without). The uptake and reduction of a tetrazolium compound as another index of cell viability also showed similar improvement with butyrate. Butyrate was associated with a striking increase of catalase to three times the control in the air exposed group while GSH content and the activities of superoxide dismutase and glutathione peroxidase were not significantly changed. In the groups exposed to hyperoxia alone, both enzyme activities were decreased compared to the air exposed controls. When butyrate was present with hyperoxia, the superoxide dismutase was maintained closer to the air exposed control values and the catalase activity remained nearly twice as high as the air exposed control cells. These results suggest that butyrate protects rat pulmonary artery smooth muscle cells from hyperoxia by increasing catalase activity which may help to preserve superoxide dismutase activity. This may be a good model to determine the biological significance of catalase and its interrelationships with other antioxidant systems within the cell.

Animals↗
PubMed1984

Butyrate inhibits the retinoic acid-induced differentiation of F9 teratocarcinoma stem cells.

F9 mouse teratocarcinoma stem cells differentiate into parietal endoderm cells in the presence of retinoic acid, dibutyryl cyclic AMP, and theophylline (RACT). When F9 cells are exposed to 2-5 mM sodium butyrate plus RACT, they fail to differentiate. Differentiation is assessed by induction of laminin and collagen IV mRNA, the synthesis of laminin, collagen IV and plasminogen activator proteins, and alterations in cell morphology. Butyrate inhibits differentiation only when added within 8 hr after retinoic acid addition. Thus an early event in retinoid action on F9 cells is butyrate-sensitive. The population doubling time and cell cycle distribution of F9 cells are not altered within the first 24 hr after butyrate addition, suggesting that butyrate does not inhibit differentiation by inhibition of growth or normal cycling. However, butyrate does inhibit histone deacetylation in F9 cells, and this could be the mechanism by which butyrate inhibits differentiation.

Acetates↗
PubMed1989

Sodium butyrate suppresses the transforming activity of an activated N-ras oncogene in human colon carcinoma cells.

The transforming activity of DNA from a newly established undifferentiated human colon carcinoma cell line (MIP-101) was tested in the NIH-3T3 transfection assay. Southern blot analysis of the transfectant DNA revealed the presence of a human N-ras oncogene. Treatment of MIP-101 cells with the maturational agent sodium butyrate induced a more normal phenotype, including diminished growth rate, elimination of anchorage independent growth, and decreased tumorigenicity (R. Niles, S. Wilhelm, P. Thomas, and N. Zamcheck (1988) J. Cancer Invest. 6, 39). Here we report that there is a significant reduction in the transforming efficiency of the DNA from butyrate-treated MIP-101 cells. A nonspecific reduction in total DNA uptake as an explanation for these findings was eliminated by showing that there was similar uptake and expression of the thymidine kinase gene from the DNA of butyrate-treated and control MIP cells. Butyrate treatment had no detectable effect on the overall structure, methylation, and level of expression of the human N-ras gene from MIP-101 cells. An NIH-3T3 transformant ability after treatment with sodium butyrate. Although butyrate suppressed several transformed properties similar to MIP-101 cells, DNA from control and treated cultures had an identical level of transforming activity. The results suggest that the environment of the MIP cells may contain additional elements not present in the NIH-3T3 transformants which are required to observe the effect of butyrate on reduction of transforming activity.

Butyrates↗
PubMed2026

Insights into specific and nonspecific butyrate-producing pathways during the in vitro fecal fermentation of butyrylated starch.

Butyrylated starch is a special type-4 resistant starch with butyrate-carrying attribute. In this study, the unique butyrate-producing capability of butyrylated starch was deeply investigated by focusing on its specific and nonspecific butyrate-producing pathways, respectively, using specially designed substrates as controls. In vitro fermentation studies revealed that butyrylated and isobutyrylated starches generated high levels of butyrate and isobutyrate, respectively, highlighting the role of butyryl group metabolism in the specificity of butyrate production. Carboxylesterase assays have demonstrated that butyryl group metabolism is primarily facilitated by carbohydrate esterases expressed in the gut microbiota. Combined with 16S rRNA sequencing and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, it was found that butyrylated starch fermentation did not significantly enhance traditional butyrate synthesis pathways but modified the balance between the butyryl-CoA:acetyl-CoA transferase and butyrate kinase pathways by altering the gut microbiota composition, specifically by upregulating the relative abundance of indicator species such as Bacteroides, the Lachnospiraceae_NK4A136_group, and Parabacteroides. These insights offer theoretical guidance for designing butyrylated starch structures and regulating intestinal health.

Starch↗
PubMed1992

Modulation of P-glycoprotein phosphorylation and drug transport by sodium butyrate.

P-Glycoprotein (Pgp) expression in cell lines derived from tumors arising from cells which normally express Pgp can be increased by sodium butyrate and other differentiating agents. Although the Pgp level increased 25-fold after sodium butyrate treatment in SW620 human colon carcinoma cells, the intracellular accumulation of vinblastine, adriamycin, and actinomycin D increased rather than decreased. In contrast, colchicine showed the expected decrease in accumulation, as a result of increased efflux. Likewise, treatment of a Pgp-expressing multidrug-resistant SW620 subline with sodium butyrate resulted in active interference with Pgp function. This effect was partially reversed by phorbol esters with a resulting decrease in the accumulation of vinblastine, adriamycin, and actinomycin D. Sodium butyrate, while increasing Pgp levels, inhibited the phosphorylation of Pgp. Time course studies revealed a tight relationship between decreased Pgp phosphorylation and increased vinblastine accumulation after sodium butyrate treatment. Either treatment with phorbol esters or withdrawal of sodium butyrate increased Pgp phosphorylation while decreasing vinblastine accumulation. These studies suggest that the specificity of Pgp transport can be modulated by phosphorylation and that vinblastine, adriamycin, or actinomycin D transport, but not that of colchicine, is diminished after dephosphorylation by sodium butyrate.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1987

Control of placental alkaline phosphatase gene expression in HeLa cells: induction of synthesis by prednisolone and sodium butyrate.

HeLa S3 cells produce an alkaline phosphatase indistinguishable from the enzyme from human term placenta. The phosphatase activity in these cells was induced by both prednisolone and sodium butyrate. Both agents stimulated de novo synthesis of the enzyme. The increase in phosphatase activity paralleled the increase in immunoactivity and biosynthesis of placental alkaline phosphatase. The fully processed phosphatase monomer in control, prednisolone-treated or butyrate-treated cells was a 64.5 K polypeptide, measured by both incorporation of L-[35S]methionine into enzyme protein and active-site labeling. The 64.5 K polypeptide was formed by the incorporation of additional N-acetylneuraminic acid moieties to a precursor polypeptide of 61.5 K. However, this biosynthetic pathway was identified only in butyrate-treated cells. In prednisolone-treated cells, the processing of 61.5 K to the 64.5 K monomer was accelerated, and the presence of the 61.5 K precursor could only be detected by either neuraminidase or monensin treatment. Phosphatase mRNA which comigrated with the term placental alkaline phosphatase mRNA of 2.7 kilobases was induced in the presence of either prednisolone or butyrate. Alkaline phosphatase mRNA in untreated HeLa S3 cells migrated slightly faster than the term placental alkaline phosphatase mRNA. Butyrate also induced a second still faster migrating alkaline phosphatase mRNA. Both prednisolone and butyrate increased the steady-state levels of placental alkaline phosphatase mRNA. Our data indicate that the increase in phosphatase mRNA by prednisolone and butyrate resulted in the induction of alkaline phosphatase activity and biosynthesis in HeLa S3 cells. Furthermore, both agents induced the expression of different alkaline phosphatase gene transcripts without altering its protein product.

Alkaline Phosphatase↗
PubMed1989

Presence of insulin receptors in cultured glial C6 cells. Regulation by butyrate.

The presence of insulin receptor and its regulation by butyrate and other short-chain fatty acids was studied in C6 cells, a rat glioma cell line. Intact C6 cells bind 125I-insulin in a rapid, reversible and specific manner. Scatchard analysis of the binding data gives typical curvilinear plots with apparent affinities of approx. 6 nM and 70 nM for the low-affinity (approx. 90% of total) and high-affinity (approx. 10% of total) sites respectively. Incubation with butyrate results in a time- and dose-dependent decrease of insulin binding to C6 cells. A maximal effect was found with 2 mM-butyrate that decreased the receptor by 40-70% after 48 h. Butyrate decreased numbers of receptors of both classes, but did not significantly alter receptor affinity. Other short-chain fatty acids, as well as keto acids, had a similar effect, but with a lower potency. Cycloheximide caused an accumulation of insulin receptors at the cell surface, since insulin binding increased and receptor affinity did not change after incubation with the inhibitor. Simultaneous addition of butyrate and cycloheximide abolished the loss of receptors produced by the fatty acid. In cells preincubated with butyrate, cycloheximide also produced a large increase in receptor numbers, showing that in the absence of new receptor synthesis a large pool of receptors re-appears at the surface of butyrate-treated cells.

Animals↗