the increased rate of metabolic diseases , such as obesity , diabetes and cardiovascular disease , has become a major public health concern . it has been shown that tight blood glucose control is helpful to reduce the risk of cardiovascular disease , a leading cause of death for patients with diabetes . liver plays a critical role in mediating glucose and lipid homeostasis regulated by hormones and nutrients . in liver and hepatocytes , insulin stimulates or inhibits the expression of a variety of genes responsible for glycolysis , glycogenesis and lipogenesis , and inhibits gluconeogenesis . this insulin - regulated hepatic gene expression , at least in part , is responsible for the control of glucose and lipid homeostasis . for hepatic glucose metabolism , insulin increases the expression of glucokinase gene ( gck ) , the enzyme responsible for the first step of hepatic glucose utilization . it suppresses the expression of the cytosolic form of phosphoenolpyruvate carboxykinase ( pck1 )   and glucose 6-phosphatase catalytic subunit ( g6pc ) , the first and last steps of gluconeogenesis , respectively . for hepatic lipid metabolism , insulin increases the expression levels of sterol regulatory element binding protein 1c gene ( srebp-1c ) . sterol regulatory element - binding proteins ( srebps ) are critical transcription activators for hepatic cholesterol and fatty acid biosynthesis , and their homeostasis . therefore , any nutritional or pharmacological factor that alters the expression of these insulin - regulated genes will have the potential to modulate or regulate the hepatic glucose and lipid homeostasis . berberine is an isoquinoline alkaloid of the protoberberine type , which is found in many plant species such as coptis chinensis franch used in traditional chinese medicine . because of its antimicrobial activity , it has been used conventionally for treatment of diarrhea . recently , it has been shown that berberine has anti - diabetic effects in experimental animals and clinical diabetic patients [ 13 - 16 ] . it lowered plasma glucose as effectively as metformin , a widely prescribed medicine for the treatment of type 2 diabetes . multiple mechanisms of berberine actions have been proposed such as increase of glycolysis , insulin secretion , and insulin receptor expression level , etc . recently , it has been shown that berberine activates amp - activated protein kinase ( ampk ) , a pathway activated by metformin as well . in addition , berberine has been shown to reduce low density lipoprotein cholesterol by up - regulating ldl receptor mrna expression . recently , it has been shown that berberine treatment inhibited hepatic gluconeogenesis in rats of an insulin - insufficient type 2 diabetic model . this has been attributed to berberine - mediated inhibition of pck1 and g6pc expression in an insulin - independent pathway . we hypothesize that the beneficiary effects of berberine on glucose and lipid metabolism may derive from its direct effects on the expression of hepatic genes involved . since insulin also regulates the expression levels of many of them , we envision that berberine may have the potential to affect insulin action as well . herein , we examined the effects of berberine hydrochloride on the expression of insulin - regulated representative genes , gck , pck1 , g6pc and srebp-1c in primary hepatocytes from normal sprague - dawley ( sd ) , zucker lean ( zl ) or zucker fatty ( zf ) rats . both zl and zf rats have been widely used as rat models for the development of obesity , insulin resistance and other aspects of metabolic diseases . reagent : berberine hydrochloride was purchased from national institutes for food and drug control ( > 97.9 % , beijing , china ) . methylthiazolyldiphenyltetrazolium bromide ( mtt ) was obtained from sigma ( saint louis , mo ) . antibodies to phospho - ampk ( thr172 ) , total ampk , phospho - akt ( ser473 ) , total akt , phospho - acetyl - coa carboxylase ( ser79 ) , total acetyl - coa carboxylase ( acc ) , and -actin , were obtained from cell signaling technologies ( danvers , ma ) . animal and hepatocytes : male sprague - dawley or zucker rats were purchased from harlan breeders ( indianapolis , in ) or bred in the department of nutrition at the university of tennessee at knoxville . primary hepatocytes were isolated from non - fasted male sd ( 10 to 14 weeks ) , zl or zf ( 9 to 11 weeks of ages ) rats , and seeded as described . after attachment , hepatocytes were washed once with 3 ml of pbs , and incubated in medium a ( medium 199 containing 100 nm dexamethasone , 100 nm t3 , 100 u / ml sodium penicillin and 100 g / ml streptomycin sulfate ) with 1 nm insulin for overnight at 37c and in 5% co2 . the hepatocytes were treated as indicated in the figure legends before the total rna or protein were extracted for real - time pcr or immunoblot analysis , respectively . mtt ( 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide ) based cell viability assay : primary hepatocytes from zl rats were washed once with 3 ml pbs and incubated in medium a without or with increasing concentrations of berberine hydrochloride in the absence or presence of 1 nm insulin for 4 h. after which , 20 l mtt ( 5 mg / ml ) was added to each well , and the cells were incubated for additional 4h . after removal of the medium , formazan crystal formed inside the cells was dissolved in 150 l dmso . the absorbance at 490 nm was measured using a packard spectra count plate reader ( model # : 851 ) . total rna isolation , cdna synthesis and quantitative real time pcr : total rna was isolated using the rna stat-60 reagent ( tel - test , inc , friendswood , tx ) according to the protocol . 3 were calculated using the comparative ct method as described   with 36b4 as the invariant control gene . rna stability assay : for rna stability assay , primary hepatocytes were washed once with 3 ml pbs and incubated in medium a without or with 3 m -amanitin in the absence or presence of 25 m berberine hydrochloride . total rnas were isolated at 0.5 , 1 , 2 , 4 , and 6 h , and subjected to real - time pcr analysis . the level of each transcript at time 0 were assigned as 100% . immunoblot analysis . after indicated treatments in the figure legends , primary hepatocytes in a 60 mm dish were washed once with 3 ml pbs and scrapped from the dish in 400 l of whole - cell lysis buffer ( 1% triton x-100 , 10% glycerol , 1.0% igepal ca-630 , 50 mm hepes , 100 mm naf , 10 mm edta , 5 mm sodium orthovanadate , 1.9 mg / ml aprotinin , 5 g / ml leupeptin , 1 mm benzamide , 2.5 mm dmsf , ph 8.0 ) . the lysates were allowed to sit on ice for at least 20 minutes before subjected to 20,000g centrifugation for 20 minutes . the protein content in the supernatant was determined with pierce bca protein assay kit ( rockford , il ) . proteins ( 30 g / lane ) in whole cell lysates were separated on sds / page , transferred to bio - rad immuno - blot pvdf membrane ( hercules , ca ) , and detected with primary antibodies according to the protocols provided by the manufacturers . bound primary antibodies were visualized by chemiluminescence ( ecl western blotting substrate ; thermo scientific ) using a 1:5,000 dilution of goat anti - rabbit igg ( upstate ) conjugated to horseradish peroxidase . filters were exposed to x - ray films ( phenix research products , candler , nc ) for protein band detection . the number of experiments represents the independent experiments using hepatocytes isolated from different animals on different days . levene 's test was used to determined homogeneity of variance among groups using spss 19.0 statistical software and where necessary natural log transformation was performed before analysis . multiple comparisons were analyzed by one - way anova using least significant different ( lsd ) when equal variance was assumed , and games - howell test was used when equal variance was not assumed . the effects of berberine hydrochloride on viability of primary hepatocytes from sd rats . to determine any cytotoxic effect , the viabilities of primary hepatocytes treated with increasing concentrations of berberine hydrochloride was measured with mtt assay as shown in fig . 1 . the viabilities of the hepatocytes treated with 1 to 25 m of berberine hydrochloride were not significantly different from that of the control group without or with insulin . however , berberine hydrochloride at 50 or 100 m reduced the viabilities to 70.7% or 60.7% ( without insulin ) , and 78.5% or 52.0% ( with insulin ) , respectively . these results demonstrated that berberine hydrochloride up to 25 m can be used to treat rat primary hepatocytes without the concern of cytotoxic effects in the current experimental settings . the effects of berberine hydrochloride on the expression of gck , g6pc , pck1 and srebp-1c in hepatocytes from sd rats . fig . 2a - d showed the relative expression levels of gck , g6pc , pck1 and srebp-1c transcripts in sd primary hepatocytes treated with vehicle control or increasing concentrations of berberine hydrochloride in the absence or presence of insulin . berberine hydrochloride alone at 10 and 25 m significantly induced the expression of gck by 3.4  1.1-fold and 5.0  2.5 -fold , respectively ( fig . 2b showed that 10 or 25 m berberine hydrochloride alone significantly reduced g6pc mrna to 0.41  0.18 or 0.14  0.04 -fold of the control value , respectively . fig . 2c showed that 25 m berberine hydrochloride reduced the pck1 expression level to 0.50  0.03 -fold of its value of the control group in the absence of insulin ( p<0.01 ) . however , berberine hydrochloride could not further reduce insulin - suppressed g6pc or pck1 expression . fig . 2d showed that 25 m berberine hydrochloride induced the expression of srebp-1c by 5.9  2.0-fold ( p<0.05 ) in the absence of insulin . surprisingly , this concentration of berberine hydrochloride attenuated insulin - induced srebp-1c expression , which was not affected by other concentrations of berberine hydrochloride tested . the effects of berberine hydrochloride on the stabilities of gck , g6pc , pck1 and srebp-1c in primary hepatocytes from zl rats . we next determined whether the change of the gene expression levels was caused by alteration of transcription or stability of the transcripts . the stabilities of the gck , g6pc , pck1 and srebp-1c mrna were measured in the presence of -amanitin , a specific inhibitor of rna polymerase ii complex . 3a , the contents of 36b4 transcripts exhibited no difference between the vehicle control and 25 m berberine hydrochloride groups . 3b - e respectively showed the decay of gck , g6pc , pck1 and srebp-1c transcripts in the absence or presence of berberine hydrochloride . at 0.5 , 1 , 2 , 4 , and 6 h after -amanitin treatment , the contents of indicated transcripts in the berberine hydrochloride group were not significant different from those in the control groups of the corresponding genes , indicating no effect of berberine hydrochloride on the decay rates of those transcripts . the estimated half life of gck , g6pc , pck1 or srebp-1c transcripts was about 1.5h , 3h , 4h or 6h for either control or berberine hydrochloride group , respectively . it indicated that berberine hydrochloride regulated the transcription of gck , g6pc , pck1 and srebp-1c in primary rat hepatocytes . the effects of berberine hydrochlorides on the expression levels of gck , g6pc , pck1 and srebp-1c in primary hepatocytes from zl rats . to determine the berberine hydrochloride effects on gene expression in hepatocytes derived from a difference strain of rats , hepatocytes were isolated from zl rats , which are insulin sensitive and have been used as controls for insulin resistant zf rats . the expression levels of gck , g6pc , pck1 and srebp-1c in zl hepatocytes treated with increasing concentrations of berberine hydrochloride ( 0 to 25 m ) in the absence or presence of insulin were analyzed as shown in fig . 4 . berberine hydrochloride started to significantly induce gck expression by 1.6  0.4-fold at 5 m in the absence of insulin ( fig . however , there was an attenuation of insulin - induced gck expression when berberine hydrochloride was at 25 m , a phenomenon not observed in sd hepatocytes . for g6pc , 10 or 25 m berberine hydrochloride alone respectively reduced g6pc mrna to 0.3  0.1 or 0.5  0.3 -fold of the control value in the absence of insulin ( fig . interestingly , 10 m or 25 m berberine hydrochloride respectively potentiated or attenuated insulin - suppressed g6pc expression , a difference with sd hepatocytes . 4c showed that 25 m berberine hydrochloride significantly attenuated insulin - suppressed pck1 expression , but had no effects on its expression in the absence of insulin , a difference with sd hepatocytes . the expression levels of g6pc and pck1 mrna in control group was not significantly different from that of insulin group when berberine hydrochloride was at 25 m , suggesting attenuation of insulin - mediated suppression of these two genes . 4d showed that in zl hepatocytes , berberine hydrochloride up to 25 m did not affect the expression of srebp-1c without insulin , a difference with sd hepatocytes . insulin no longer induced srebp-1c when berberine hydrochloride concentration was 25 m , a similar phenomenon in sd hepatocytes . the effects of berberine hydrochlorides on the expression levels of gck , g6pc , pck1 and srebp-1c in primary hepatocytes from zf rats . to determine the berberine effects on gene expression in hepatocytes from insulin resistant animals , we used primary hepatocytes from obese and insulin resistant zf rats . 5a - d respectively showed the relative expression levels of gck , g6pc , pck1 and srebp-1c transcripts in zf primary hepatocytes treated with vehicle control or increasing concentrations of berberine hydrochloride in the absence or presence of 1 nm insulin . in the absence of insulin , berberine hydrochloride at 5 m started to induce gck expression by 1.9  0.5-fold ( fig . insulin induced the level of gck transcript to 6.5  1.0- fold of the control value in the absence of berberine hydrochloride . berberine hydrochloride at 5 and 10 m significantly potentiated insulin - induced expression of gck , suggesting an additive effect between insulin and these two concentrations of berberine on gck expression in zf hepatocytes . 5b and 5c showed that berberine hydrochloride alone at 2.5 and 1 m started to significantly suppress g6pc and pck1 expression in zf hepatocytes , respectively . the levels of g6pc and pck1 transcripts in 10 m berberine hydrochloride treatment group reached 0.11  0.01- and 0.32  0.02-fold of the control value , respectively . interestingly , the pck1 expression levels in 25 m treatment group were higher than those in 5 and 10 m berberine hydrochloride groups ( fig . insulin respectively reduced the levels of g6pc and pck1 transcript to 0.35  0.07- and 0.25  0.03-fold of the control value . in the presence of 1 nm insulin , berberine hydrochloride at 2.5 to 25 m further reduced the expression levels of g6pc transcript , but not pck1 , in zf hepatocytes . the effects of berberine hydrochloride on the expression of srebp-1c in hepatocytes from zf rats were weak at the most . 5d showed that berberine hydrochloride did not significantly affect srebp-1c expression in the absence of insulin . this weak induction no longer existed when berberine hydrochloride was at 5 m or higher , suggesting attenuation of insulin - induced srebp-1c expression by berberine treatment in zf hepatocytes . 6 showed that berberine hydrochloride treatment started to cause phosphorylation of ampk subunits at threonine 172 as low as 3 m in zl hepatocytes . this phosphorylation of ampk correlated with an induction of phosphorylation of its substrate , acc , at serine 79 in the absence or presence of 1 nm insulin . insulin treatment resulted in phosphorylation of its downstream signaling target , akt at serine 473 , demonstrating the activation of insulin signaling transduction pathway . there are no significant changes of total ampk , acc , akt , and -actin in the same hepatocytes treated without and with berberine hydrochloride in the absence or presence of insulin . in this study , we reported the effects of berberine hydrochloride on the expression of hepatic genes involved in glucose and lipid metabolism . it has been reported that berberine administrated orally was well tolerated in rodents ( 100 to 300 mg / kg ) and human ( 500 mg two to three times per day / person ) [ 13 - 16 ] . the dosages used here were similar to the concentrations used ( 5 to 15 g / ml which are equivalent to 15 to 45 m ) in previous reports showing activation of signal transduction pathways   and regulation of gene expression . our results demonstrated that 25 m berberine hydrochloride was well tolerated by primary hepatocytes in the current experimental settings ( fig . the observed cytotoxic effect of 50 or 100 m berberine hydrochloride was reasonable as berberine and its derivatives inhibited activity of mitochondrial complex i of electron transport chain . the tolerance of berberine in the in vivo studies may be attributed to its poor bioavailability due to the p - glycoprotein on small intestine , which actively pumps berberine back into the intestinal lumen . this might have prevented higher concentrations of berberine in plasma and exerted toxic effects on liver . recently , some attempts have been taken to modify the structure of berberine and identify its analogues for the improvement of its bioavailability and efficacy [ 28,30 - 33 ] . whether any of those derivatives and analogues has the same effects on viability of primary hepatocytes remains to be seen . in addition , how berberine and its derivatives are transported and catabolized in primary hepatocytes also deserves to be investigated . nevertheless , the results shown here have provided a reference for future berberine studies in primary hepatocytes . we initiated our studies using hepatocytes from sd rats and observed the effects of berberine hydrochloride on gene expression in them ( fig . subsequently , we decided to examine berberine effects on hepatocytes in insulin resistant zucker fatty rats . therefore , we conducted similar dosage experiments in hepatocytes ( fig . 4 ) from zl rats which are insulin sensitive and have been used as the controls for obese and insulin resistant zf rats . in hepatocytes from both sd and zl rats , berberine hydrochloride at 10 and 25 m increased gck , and suppressed g6pc expression in the absence of insulin . however , the magnitude of the induction or suppression was not the same as that mediated by insulin ( fig . 2 and 4 ) . in hepatocytes from either sd or zl rats , berberine hydrochloride at 25 m attenuated insulin - induced srebp-1c expression nevertheless , the hepatocytes from these two strains of rats showed some differences regarding the responses of these genes to berberine hydrochloride treatments . for gck , berberine hydrochloride at 25 m attenuated insulin - induced its expression in zl , but not sd hepatocytes . the same treatment reversed berberine hydrochloride- and insulin - suppressed g6pc expression to a certain extent in zl , but not in sd hepatocytes . for pck1 , berberine hydrochloride at 25 m reduced its expression in sd , but not in zl hepaotcytes in the absence of insulin . in the presence of insulin , it only attenuated insulin - suppressed pck1 expression in zl , but not in sd hepatocytes . berberine hydrochloride started to induce srebp-1c expression at 10 m in sd , but not zl in hepatocytes . all these results demonstrated that berberine hydrochloride had the ability to regulate the expression of these four insulin - regulated genes in primary hepatocytes . the regulation can be masked by insulin treatment ( such as gck and g6pc ) . on the other hand , berberine hydrochloride can modify insulin 's action on the expression of its downstream target gene ( such as srebp-1c ) . in addition , some of the effects on a particular gene expression ( such as pck1 ) may depend on the strain of rats from which the hepatocytes were obtained . the fact that berberine hydrochloride did not change the mrna stabilities of these four genes ( fig . 3 ) indicated that it regulated their transcription in primary hepatocytes , which is also regulated by insulin . in the process of submitting our current manuscript , a report came out and demonstrated that berberine inhibited hepatic pck1 and g6pc expression in an insulin - independent pathway . our results showed that berberine directly regulated these two genes ' transcription , which is in agreement with their observations . in addition , we also demonstrated that berberine can induce the expression of gck , suggesting glucose usage as another target of berberine action in liver . it has been shown the metformin , another reagent that activates ampk , and insulin suppressed hepatic pck1 and g6pc expression through phosphorylation of creb binding protein . both metformin and insulin treatments caused activation of pkc/ via activation of ampk and phosphoinositide - dependent protein kinase 1 ( pdk1 ) , respectively . given the effects of berberine hydrochloride on gck , pck1 and g6pc expression , it seems that insulin and berberine activated a common signaling pathway that leads to regulation of these genes ' transcription in primary rat hepatocytes . however , given the effects of berberine hydrochloride on srebp-1c expression in the presence of insulin , it seems that berberine antagonized part of insulin - regulated gene expression . it has been shown that insulin - mediated induction of srebp-1c expression and suppression of pck1 expression bifurcated at mtor step , which is downstream of pdk1 activation . berberine hydrochloride treatment might have activated part of insulin - mediated pathways involved in glucose metabolism and antagonized insulin - induced srebp-1c expression . whether the berberine signaling in hepatocytes shares part of insulin pathways or the beneficial effects of berberine on type 2 diabetes and insulin resistance subjects [ 13 - 16 ] indicated that it may have effects on hepatocytes isolated from insulin resistant fatty rats . in a different manuscript , we have reported that the insulin - regulated gene expression in zf hepatocytes was impaired or diminished when compared to that in zl hepatocytes . our results shown here also supported this claim when the fold inductions of these four genes in zl and zf hepatocytes were compared ( fig . 4 and fig . 5 ) . we showed here that berberine hydrochloride increased gck expression in fatty hepatocytes as it did in sd and zl hepatocytes ( fig . the difference here is that berberine and insulin had additive effects on the induction of gck expression in fatty hepatocytes , but not in sd or zl cells . for g6pc expression , berberine suppressed its expression in zf hepatocytes as low as 2.5 m , a concentration that could not affect g6pc expression in sd and zl hepatocytes . in addition , berberine potentiated insulin - suppressed g6pc expression at concentration as low as 2.5 m . for pck1 expression in zf hepatocytes , berberine suppressed its expression levels in the absence of insulin at concentration as low as 1 m , which was not observed in sd or zl hepatocytes . unlike its effects on g6pc expression for srebp-1c , berberine hydrochloride had almost no effect on its expression in fatty hepatocytes without or with insulin . the unresponsiveness of srebp-1c to berberine hydrochloride treatment in fatty hepatocytes could be caused by the elevated expression of srebp-1c   or alteration of the mechanisms of its regulation in fatty hepatocytes . these results indicated that the expression levels of gck , g6pc and pck1 were more sensitive to berberine treatment in zf hepatocytes than in sd or zl hepatocytes . in addition , insulin - regulated gck and g6pc can be modified in the presence of berberine hydrochloride ( 5 and 10 m ) , suggesting improvement of insulin action . whether the pre - existence of insulin resistance in the zf hepatocytes plays a role here or not deserves further study . our results demonstrated that berberine hydrochloride dose - dependently induced phosphorylation of ampk in primary hepatocytes without or with insulin . the phosphorylation of ampk in primary hepatocytes correlated with an increase of the phosphorylation of its substrate acc , demonstrating the elevation of ampk activity after berberine hydrochloride treatment in primary hepatocytes ( fig . 6 ) . this activation of ampk was not affected by the presence of insulin , which induces phosphorylation of akt , a downstream kinase mediating insulin signaling pathway . it has been shown that berberine activated ampk in 3t3-l1 adipocytes   and in l6 myotubes . this ampk activation mediated by berberine hydrochloride treatment might have contributed to the attenuation of insulin - induced srebp-1c expression in the presence of berberine hydrochloride ( fig . 2 , 4 and 5 ) . reduction of plasma triglyceride and cholesterol levels were observed in hypercholesterolemic patients treated with berberine . given the critical role of srebp-1c in hepatic lipogenesis , this antagonization of berberine hydrochloride to insulin - induced srebp-1c expression might have contributed to the hypolipidemic effects of berberine . however , it is worth to note that in zl hepatocytes , berberine hydrochloride at 10 and 25 m potentiated and attenuated insulin - suppressed g6pc expression , respectively ( fig . one explanation is that the degree of ampk phosphorylation might have played a role here . as shown in fig . 6 , phosphorylation of ampk was further enhanced with the rise of berberine hydrochloride concentrations from 10 m to 30 m . the additional phosphorylation of ampk might have changed the dynamic of ampk activation , which might have contributed negatively to insulin 's effects on g6pc expression . this phosphorylation resulted in suppression of its activity , which is responsible for the inhibition of mtorc1 and cell - cycle arrest induced by energy stress . alternatively , another signaling pathway might have been activated by 25 m berberine hydrochloride , which might have contributed to the phenomenon . the activation of ampk alone may not be enough to explain all the berberine hydrochloride effects . it has been shown that metformin , another antidiabetic drug that can activate ampk , still suppressed hepatic gluconeogenesis in mice without ampk catalytic subunits ( ampk knockout ) . given the different functions of these four genes in glucose and lipid metabolism , it is possible that ampk activation may not be the only reason for the observed effects of berberine on these four genes ' expression in primary hepatocytes . the mechanisms by which berberine hydrochloride affect hepatic genes involved in glucose metabolism remain to be investigated . in summary , we demonstrated that berberine hydrochloride regulated the transcription of representative genes involved in glucose and fatty acid synthesis in hepatocytes from either insulin sensitive rats ( sd and fl ) or resistant ( zf ) rats . it suggests that the beneficial effects of berberine on diabetes and hyperlipidemia [ 13 - 16 ] may have something to do , at least in part , with the berberine - regulated transcription of hepatic genes involved in glucose and lipid metabolism . the berberine - mediated ampk activation may contribute in part to its effects on insulin - regulated gene expression . further understanding of the activation mechanism of berberine in hepatocytes may provide us with new tools to combat metabolic diseases .
the effects of hormonal and dietary stimuli on hepatic glucose and lipid homeostasis include regulation of gene expression . 
 berberine , an effective compound in certain chinese medicinal herbs , has been reported to lower plasma glucose and lipid levels in diabetic and hypercholesterolemic patients . 
 we hypothesized that it may affect the expression of hepatic genes involved in glucose and lipid metabolism . 
 the effects of berberine hydrochloride on viability , gene expression , and activation of amp activated protein kinase ( ampk ) in primary hepatocytes from sprague - dawley ( sd ) , zucker lean ( zl ) or fatty ( zf ) rats were examined with mtt assay , real - time pcr , and western blotting , respectively . 
 berberine hydochloride at 50 m or higher caused cytotoxic effects on hepatocytes . 
 in sd and zl hepatocytes , it induced gck and suppressed g6pc expression at 10 and 25 m , but not as potent as 1 nm insulin . 
 its effects on pck1 , and insulin - regulated gck and g6pc expression depended on the hepatocyte sources and the dosage used . in zf hepatocytes , it increased gck , and suppressed pck1 and g6pc expression without insulin . 
 its effects on gck and g6pc , but not pck1 expression , were additive with insulin . 
 berberine hydrochloride at 25 m attenuated insulin - suppressed pck1 ( zl / zf cells ) , and insulin - induced srebp-1c expression ( sd / zl / zf cells ) , suggesting modulation of insulin action . 
 berberine hydrochloride did not alter these genes ' mrna stability . 
 its treatment caused a dose - dependent increase of phosphorylation of ampk , and its substrate , acetyl - coa carboxylase , in primary hepatocytes . 
 we conclude that berberine hydrochloride regulated the transcription of hepatic genes involved in glucose and fatty acid metabolism .