Attenuation Effect of Spinal Manipulation on Neuropathic and Postoperative Pain Through Activating Endogenous Anti-Inflammatory Cytokine Interleukin 10 in Rat Spinal Cord.

OBJECTIVES: The purpose of this study was to investigate roles of the anti-inflammatory cytokine interleukin (IL) 10 and the proinflammatory cytokines IL-1ß and tumor necrosis factor α (TNF-α) in spinal manipulation-induced analgesic effects of neuropathic and postoperative pain. METHODS: Neuropathic and postoperative pain were mimicked by chronic compression of dorsal root ganglion (DRG) (CCD) and decompression (de-CCD) in adult, male, Sprague-Dawley rats. Behavioral pain after CCD and de-CCD was determined by the increased thermal and mechanical hypersensitivity of the affected hindpaw. Hematoxylin and eosin staining, whole-cell patch clamp electrophysiological recordings, immunohistochemistry, and enzyme-linked immunosorbent assay were used to examine the neural inflammation, neural excitability, and expression of c-Fos and PKC as well as levels of IL-1ß, TNF-α, and IL-10 in blood plasma, DRG, or the spinal cord. We used the activator adjusting instrument, a chiropractic spinal manipulative therapy tool, to deliver force to the spinous processes of L5 and L6. RESULTS: After CCD and de-CCD treatments, the animals exhibited behavioral and neurochemical signs of neuropathic pain manifested as mechanical allodynia and thermal hyperalgesia, DRG inflammation, DRG neuron hyperexcitability, induction of c-Fos, and the increased expression of PKCγ in the spinal cord as well as increased level of IL-1ß and TNF-α in DRG and the spinal cord. Repetitive Activator-assisted spinal manipulative therapy significantly reduced simulated neuropathic and postoperative pain, inhibited or reversed the neurochemical alterations, and increased the anti-inflammatory IL-10 in the spinal cord. CONCLUSION: These findings show that spinal manipulation may activate the endogenous anti-inflammatory cytokine IL-10 in the spinal cord and thus has the potential to alleviate neuropathic and postoperative pain.

Activation of cGMP-PKG signaling pathway contributes to neuronal hyperexcitability and hyperalgesia after in vivo prolonged compression or in vitro acute dissociation of dorsal root ganglion in rats.

Injury or inflammation affecting sensory neurons in the dorsal root ganglia (DRG) causes hyperexcitability of DRG neurons that can lead to spinal central sensitization and neuropathic pain. Recent studies have indicated that, following chronic compression of DRG (CCD) or acute dissociation of DRG (ADD) treatment, both hyperexcitability of neurons in intact DRG and behaviorally expressed hyperalgesia are maintained by activity in cGMP-PKG signaling pathway. Here, we provide evidence supporting the idea that CCD or ADD treatment activates cGMP-PKA signaling pathway in the DRG neurons. The results showed that CCD or ADD results in increase of levels of cGMP concentration and expression of PKG-I mRNA, as well as PKG-I protein in DRG. CCD or ADD treated-DRG neurons become hyperexcitable and exhibit increased responsiveness to the activators of cGMP-PKG pathway, 8-Br-cGMP and Sp-cGMP. Hyperexcitability of the injured neurons is inhibited by cGMP-PKG pathway inhibitors, ODQ and Rp-8-pCPT-cGMPS. In vivo delivery of Rp-8-pCPT-cGMPS into the compressed ganglion within the intervertebral foramen suppresses CCD-induced thermal hyperalgesia. These findings indicate that the in vivo CCD or in vitro ADD treatment can activate the cGMP-PKG signaling pathway, and that continuing activation of cGMP-PKG pathway is required to maintain DRG neuronal hyperexcitability and/or hyperalgesia after these two dissimilar forms of injury-related stress.

EphB receptor signaling in mouse spinal cord contributes to physical dependence on morphine.

Cellular and molecular mechanisms underlying opioid tolerance and dependence remain elusive. We investigated roles of EphB receptor tyrosine kinases--which play important roles in synaptic connection and plasticity during development and in the matured nervous system--in development and maintenance of physical dependence on morphine in the mouse spinal cord (SC). Spinal administration of an EphB receptor blocking reagent EphB2-Fc prevents and/or suppresses behavioral responses to morphine withdrawal and associated induction of c-Fos and depletion of calcitonin gene-related peptide. Western blotting and immunohistochemical fluorescence staining demonstrates that EphB1 receptor protein is significantly up-regulated in the spinal dorsal horn following escalating morphine treatment. Chronic morphine exposure and withdrawal significantly increased phosphorylation of N-methyl-D-aspartate receptor subunit NR2B as well as the activated forms of extracellular signal-regulated kinase and the cAMP response element binding protein in SC. The increased levels of phosphorylation of these molecules, however, are significantly inhibited by the EphB receptor blocker. These findings indicate that EphB receptor signaling, probably by interacting with NR2B in SC, contributes to the development of opioid physical dependence and withdrawal effects. This novel role for EphB receptor signaling suggests that these molecules may be useful therapeutic targets for preventing, minimizing, or reversing the development of opiate dependence.

Thiamine suppresses thermal hyperalgesia, inhibits hyperexcitability, and lessens alterations of sodium currents in injured, dorsal root ganglion neurons in rats.

BACKGROUND: B vitamins can effectively attenuate inflammatory and neuropathic pain in experimental animals, while their efficacy in treating clinical pain syndromes remains unclear. To understand possible mechanisms underlying B vitamin-induced analgesia and provide further evidence that may support the clinical utility of B vitamins in chronic pain treatment, this study investigated effects of thiamine (B1) on the excitability and Na currents of dorsal root ganglion (DRG) neurons that have been altered by nerve injury. METHODS: Nerve injury was mimicked by chronic compression of DRG in rats. Neuropathic pain was evidenced by the presence of thermal hyperalgesia. Intracellular and patch-clamp recordings were made in vitro from intact and dissociated DRG neurons, respectively. RESULTS: (1) In vivo intraperitoneal administration of B1 (66 mg/kg/day, 10-14 doses) significantly inhibited DRG compression-induced neural hyperexcitability, in addition to suppressing thermal hyperalgesia. (2) In vitro perfusion of B1 (0.1, 1 and 10 mM) resulted in a dose-dependent inhibition of DRG neuron hyperexcitability. In addition, the DRG neurons exhibited size-dependent sensitivity to B1 treatment, i.e., the small and the medium-sized neurons, compared to the large neurons, were significantly more sensitive. (3) Both in vitro (1 mM) and in vivo application of B1 significantly reversed DRG compression-induced down-regulation of tetrodotoxin-resistant but not tetrodotoxin-sensitive Na current density in the small neurons. B1 at 1 mM also reversed the compression-induced hyperpolarizing shift of the inactivation curve of the tetrodotoxin-resistant currents and the upregulated ramp currents in small DRG neurons. CONCLUSION: Thiamine can reduce hyperexcitability and lessen alterations of Na currents in injured DRG neurons, in addition to suppressing thermal hyperalgesia.

Differing alterations of sodium currents in small dorsal root ganglion neurons after ganglion compression and peripheral nerve injury.

Voltage-gated sodium channels play important roles in modulating dorsal root ganglion (DRG) neuron hyperexcitability and hyperalgesia after peripheral nerve injury or inflammation. We report that chronic compression of DRG (CCD) produces profound effect on tetrodotoxin-resistant (TTX-R) and tetrodotoxin-sensitive (TTX-S) sodium currents, which are different from that by chronic constriction injury (CCI) of the sciatic nerve in small DRG neurons. Whole cell patch-clamp recordings were obtained in vitro from L4 and/or L5 dissociated, small DRG neurons following in vivo DRG compression or nerve injury. The small DRG neurons were classified into slow and fast subtype neurons based on expression of the slow-inactivating TTX-R and fast-inactivating TTX-S Na+ currents. CCD treatment significantly reduced TTX-R and TTX-S current densities in the slow and fast neurons, but CCI selectively reduced the TTX-R and TTX-S current densities in the slow neurons. Changes in half-maximal potential (V1/2) and curve slope (k) of steady-state inactivation of Na+ currents were different in the slow and fast neurons after CCD and CCI treatment. The window current of TTX-R and TTX-S currents in fast neurons were enlarged by CCD and CCI, while only that of TTX-S currents in slow neurons was increased by CCI. The decay rate of TTX-S and both TTX-R and TTX-S currents in fast neurons were reduced by CCD and CCI, respectively. These findings provide a possible sodium channel mechanism underlying CCD-induced DRG neuron hyperexcitability and hyperalgesia and demonstrate a differential effect in the Na+ currents of small DRG neurons after somata compression and peripheral nerve injury. This study also points to a complexity of hyperexcitability mechanisms contributing to CCD and CCI hyperexcitability in small DRG neurons.

Wnt/Ryk signaling contributes to neuropathic pain by regulating sensory neuron excitability and spinal synaptic plasticity in rats.

Treating neuropathic pain continues to be a major clinical challenge and underlying mechanisms of neuropathic pain remain elusive. We have recently demonstrated that Wnt signaling, which is important in developmental processes of the nervous systems, plays critical roles in the development of neuropathic pain through the ß-catenin-dependent pathway in the spinal cord and the ß-catenin-independent pathway in primary sensory neurons after nerve injury. Here, we report that Wnt signaling may contribute to neuropathic pain through the atypical Wnt/Ryk signaling pathway in rats. Sciatic nerve injury causes a rapid-onset and long-lasting expression of Wnt3a, Wnt5b, and Ryk receptors in primary sensory neurons, and dorsal horn neurons and astrocytes. Spinal blocking of the Wnt/Ryk receptor signaling inhibits the induction and persistence of neuropathic pain without affecting normal pain sensitivity and locomotor activity. Blocking activation of the Ryk receptor with anti-Ryk antibody, in vivo or in vitro, greatly suppresses nerve injury-induced increased intracellular Ca and hyperexcitability of the sensory neurons, and also the enhanced plasticity of synapses between afferent C-fibers and the dorsal horn neurons, and activation of the NR2B receptor and the subsequent Ca-dependent signals CaMKII, Src, ERK, PKCγ, and CREB in sensory neurons and the spinal cord. These findings indicate a critical mechanism underlying the pathogenesis of neuropathic pain and suggest that targeting the Wnt/Ryk signaling may be an effective approach for treating neuropathic pain.

[Inhibitory action of berberine on glucose absorption].

AIM: To study the absorption characteristics of berberine and its influence on glucose absorption. METHODS: Rat recirculating perfusion model was used to study berberine absorption characteristics and Caco-2 cell model was used to explore the influence of berberine on disaccharidase, using HPLC to assay the appearance of glucose to indicate enzyme activities. RESULTS: Berberine was found to be hardly absorbed in the intestine (less than 5% in 2.5 h). However, sucrase and maltase activities were found to be inhibited by berberine, its ID50 to sucrase is 1.830 mg.L-1, and showed no dose dependent influence on maltase activity. Berberine also showed influence on glucose absorption. However, this effect is not significant. CONCLUSION: Berberine may act as an alpha-glucosidase inhibitor, which is its main mechanism in diabetes treatment.

WNT signaling underlies the pathogenesis of neuropathic pain in rodents.

Treating neuropathic pain is a major clinical challenge, and the underlying mechanisms of neuropathic pain remain elusive. We hypothesized that neuropathic pain-inducing nerve injury may elicit neuronal alterations that recapitulate events that occur during development. Here, we report that WNT signaling, which is important in developmental processes of the nervous system, plays a critical role in neuropathic pain after sciatic nerve injury and bone cancer in rodents. Nerve injury and bone cancer caused a rapid-onset and long-lasting expression of WNTs, as well as activation of WNT/frizzled/ß-catenin signaling in the primary sensory neurons, the spinal dorsal horn neurons, and astrocytes. Spinal blockade of WNT signaling pathways inhibited the production and persistence of neuropathic pain and the accompanying neurochemical alterations without affecting normal pain sensitivity and locomotor activity. WNT signaling activation stimulated production of the proinflammatory cytokines IL-18 and TNF-α and regulated the NR2B glutamate receptor and Ca2+-dependent signals through the ß-catenin pathway in the spinal cord. These findings indicate a critical mechanism underlying the pathogenesis of neuropathic pain and suggest that targeting the WNT signaling pathway may be an effective approach for treating neuropathic pain, including bone cancer pain.

Chronic compression or acute dissociation of dorsal root ganglion induces cAMP-dependent neuronal hyperexcitability through activation of PAR2.

Chronic compression (CCD) or dissociation of dorsal root ganglion (DRG) can induce cyclic adenosine monophosphate (cAMP)-dependent DRG neuronal hyperexcitability and behaviorally expressed hyperalgesia. Here, we report that protease-activated receptor 2 (PAR2) activation after CCD or dissociation mediates the increase of cAMP activity and protein kinase A (PKA) and cAMP-dependent hyperexcitability and hyperalgesia in rats. CCD and dissociation, as well as trypsin (a PAR2 activator) treatment, increased level of cAMP concentration, mRNA, and protein expression for PKA subunits PKA-RII and PKA-c and protein expression of PAR2, in addition to producing neuronal hyperexcitability and, in CCD rats, thermal hyperalgesia. The increased expression of PAR2 was colocalized with PKA-c subunit. A PAR2 antagonistic peptide applied before and/or during the treatment, prevented or largely diminished the increased activity of cAMP and PKA, neuronal hyperexcitability, and thermal hyperalgesia. However, posttreatment with the PAR2 antagonistic peptide failed to alter either hyperexcitability or hyperalgesia. In contrast, an adenylyl cyclase inhibitor, SQ22536, administrated after dissociation or CCD, successfully suppressed hyperexcitability and hyperalgesia, in vitro and/or in vivo. Trypsin-induced increase of the intracellular calcium [Ca(2+)](i) was prevented in CCD or dissociation DRG neurons. These alterations were further confirmed by knockdown of PAR2 with siRNA. In addition, trypsin and PAR2 agonistic peptide-induced increase of cAMP was prevented by inhibition of PKC, but not Gαs. These findings suggest that PAR2 activation is critical to induction of nerve injury-induced neuronal hyperexcitability and cAMP-PKA activation. Inhibiting PAR2 activation may be a potential target for preventing/suppressing development of neuropathic pain.

Topical application of compound Ibuprofen suppresses pain by inhibiting sensory neuron hyperexcitability and neuroinflammation in a rat model of intervertebral foramen inflammation.

UNLABELLED: There is lack of evidence that topical application of an anti-inflammatory reagent could reduce pain due to intervertebral foramen (IVF) inflammation (IVFI). We investigated analgesic effects and underlying mechanisms of topical application of a compound ibuprofen cream (CIC) onto the surface of back skin covering the inflamed L(5) IVF in a rat model. Repetitive CIC treatment (~.54 g each treatment daily for 5 consecutive days) significantly reduces severity and duration of IVFI-induced thermal hyperalgesia and mechanical allodynia by 80 to 100% and 50 to 66%, respectively. Electrophysiological studies and Western blot analysis demonstrated that CIC treatment significantly inhibited hyperexcitability of the inflamed dorsal root ganglion (DRG) neurons and upregulation of Nav1.7 and Nav1.8 protein, respectively. Pathological manifestations of the inflamed DRG were also markedly improved following CIC treatment. Further, in the inflamed DRGs, phosphorylation and expression of transcription factor NF-κB and pro-inflammatory enzyme cyclooxygenase-2 (COX-2) were significantly increased, while a cytokine IL-1ß level was increased. IVFI-induced upregulation of these molecules was significantly inhibited by CIC treatment. This study provides evidence that an anti-inflammatory reagent can be used topically to suppress pain due to IVFI and/or DRG inflammation through inhibition of sensory neuron hyperexcitability and the immune and inflammatory responses. PERSPECTIVE: This study suggests a convenient and safe clinical intervention for treating pain due to intervertebral foramen inflammation and similar syndromes.

Reopening of ATP-sensitive potassium channels reduces neuropathic pain and regulates astroglial gap junctions in the rat spinal cord.

Adenosine triphosphate-sensitive potassium (K(ATP)) channels are suggested to be involved in pathogenesis of neuropathic pain, but remain underinvestigated in primary afferents and in the spinal cord. We examined alterations of K(ATP) channels in rat spinal cord and tested whether and how they could contribute to neuropathic pain. The results showed that protein expression for K(ATP) channel subunits SUR1, SUR2, and Kir6.1, but not Kir6.2, were significantly downregulated and associated with thermal hyperalgesia and mechanical allodynia after sciatic nerve injury. Spinal administration of a K(ATP) channel opener cromakalim (CRO, 5, 10, and 20 µg, respectively) prevented or suppressed, in a dose-dependent manner, the hyperalgesia and allodynia. Nerve injury also significantly increased expression and phosphorylation of connexin 43, an astroglial gap junction protein. Such an increase of phosphorylation of connexin 43 was inhibited by CRO treatment. Furthermore, preadministration of an astroglial gap junction decoupler carbenoxolone (10 µg) completely reversed the inhibitory effects of CRO treatment on the hyperalgesia and allodynia and phosphorylation of NR1 and NR2B receptors and the subsequent activation of Ca(2+)-dependent signals Ca(2+)/calmodulin-dependent kinase II and cyclic adenosine monophosphate (cAMP) response element binding protein. These findings suggest that nerve injury-induced downregulation of the K(ATP) channels in the spinal cord may interrupt the astroglial gap junctional function and contribute to neuropathic pain, thus the K(ATP) channels opener can reduce neuropathic pain probably partly via regulating the astroglial gap junctions. This study may provide a new strategy for treating neuropathic pain using K(ATP) channel openers in the clinic.

EphrinB-EphB receptor signaling contributes to neuropathic pain by regulating neural excitability and spinal synaptic plasticity in rats.

Bidirectional signaling between ephrins and Eph receptor tyrosine kinases was first found to play important roles during development, but recently has been implicated in synaptic plasticity and pain processing in the matured nervous system. We show that ephrinB-EphB receptor signaling plays a critical role is induction and maintenance of neuropathic pain by regulating neural excitability and synaptic plasticity in the dorsal root ganglion (DRG) and the spinal dorsal horn (DH). Intrathecal application of blocking reagents for EphB-receptors, EphB1-Fc and EphB2-Fc chimeras inhibits the induction and maintenance of nerve injury-induced thermal hyperalgesia and mechanical allodynia. These blockers also prevent and suppress the nerve injury-induced hyperexcitability of nociceptive small DRG neurons, sensitization of DH neurons and long-term potentiation (LTP) of synapses between C fibers and DH neurons. In naïve, uninjured animals intrathecal administration of EphB-receptor activators ephrinB1-Fc and ephrinB2-Fc, respectively, induces thermal hypersensitivity and lowers the threshold for LTP, while EphB1-Fc prevents induction of the LTP. Western Blot analysis shows that nerve injury triggers an upregulation of the ephrinB1 and EphB1 receptor proteins in DRG and the spinal cord. These results indicate that, by regulating excitability of nociceptive-related neurons in DRG and DH and the synaptic plasticity at the spinal level, ephrinB-EphB receptor signaling contributes to neuropathic pain. This novel role for ephrinB-EphB receptor signaling suggests that these molecules may be useful therapeutic targets for treating pain after nerve injury.

Downregulated FKBP12.6 expression and upregulated endothelin signaling contribute to elevated diastolic calcium and arrhythmogenesis in rat cardiomyopathy produced by l-thyroxin.

BACKGROUND: Dissociation of FKBP12.6 from RyR2 is considered as an important molecular event resulting in calcium leak and an increased risk in arrhythmogenesis. We hypothesized that augmented ventricular fibrillation (VF) on reperfusion of rat cardiomyopathy induced by l-thyroxin may result from elevated diastolic Ca(2+) levels due to dissociation (downregulation) of FKBP12.6 and upregulation of endothelin (ET-1) signaling pathway. METHODS: Rats were treated with l-thyroxin (0.4 mg/kg, s.c.) for 10 days. Dajisentan (CPU0213), a dual endothelin receptor antagonist (100 mg/kg p.o.), or propranolol was administered on day 6 to 10. Susceptibility to VF was evaluated on ischemia/reperfusion episode. mRNA expression of FKBP12.6, and ET-1 levels were determined. Calcium transients and FKBP12.6 immunohistochemistry were measured by confocal microscopy in isolated cardiomyocytes from cardiomyopathy. RESULTS: Cardiomyopathy induced by l-thyroxin resulted in an increased susceptibility to VF on ischemia/reperfusion. Upregulated mRNA expression of RyR2 and PKA in association with downregulated FKBP12.6 expression was found in l-thyroxin-treated rats compared to controls. Calcium transients evoked by field electrical stimulation showed an increase in Ca(2+) by +75% during diastole. An increase in ET-1 (ng/mg protein) (+36.6%) and mRNA abundance of preproET-1 were found in the left ventricle. A decreased mRNA ratio of FKBP12.6 to RyR2 likely reflected dissociation of FKBP12.6 in cardiomyopathy. These changes were normalized by Dajisentan, comparable to propranolol. CONCLUSION: Increased susceptibility to VF in l-thyroxin-induced cardiomyopathy is related to increase in diastolic Ca(2+) levels, resulting from downregulated FKBP12.6 and upregulated ET system. ET antagonism might be useful in settings of FKBP12.6 dissociation.

Calcium antagonist property of CPU228, a dofetilide derivative, contributes to its low incidence of torsades de pointes in rabbits.

1. Torsades de pointes (TDP) is a severe adverse effect during the clinical use of dofetilide, a selective blocker of the rapid component of the delayed rectifier potassium channel (I(Kr)). The present study was designed to test whether CPU228, a derivative of dofetilide with calcium (Ca(2+)) antagonist properties, could reduce TDP without reducing the blockade of I(Kr). 2. The incidence of TDP in a rabbit model and the effective refractory period (ERP) were measured and compared for dofetilide and CPU228. Suppression of I(Kr) and the L-type Ca(2+) current (I(Ca,L)) and the Ca(2+) transients of isolated cardiomyocytes were investigated by whole-cell patch-clamp and Fluo-3 dye spectrophotometry. 3. The incidence of TDP was greatly reduced by CPU228 relative to dofetilide, occurring in only one of six rabbits compared with five of six rabbits following dofetilide (P < 0.05). In isolated atria, prolongation of ERP by CPU228 was less than that of dofetilide and no reverse frequency dependence was observed. Negative inotropism by CPU228 was significant against positive inotropism by dofetilide. CPU228 inhibited both I(Kr) and I(Ca,L) currents and the IC(50) for I(Ca,L) inhibition was 0.909 micromol/L. At 3 micromol/L, CPU228 significantly suppressed the Ca(2+) transients. 4. CPU228 is able to block I(Ca,L), contributing to decreased TDP, while also blocking I(Kr) activity. By combined blockade of I(Kr) and I(Ca,L), CPU228 shares the property of complex Class III anti-arrhythmic agents.

Abrupt changes in FKBP12.6 and SERCA2a expression contribute to sudden occurrence of ventricular fibrillation on reperfusion and are prevented by CPU86017.

AIM: The occurrence of ventricular fibrillation (VF) is dependent on the deterioration of channelopathy in the myocardium. It is interesting to investigate molecular changes in relation to abrupt appearance of VF on reperfusion. We aimed to study whether changes in the expression of FKBP12.6 and SERCA2a and the endothelin (ET) system on reperfusion against ischemia were related to the rapid occurrence of VF and whether CPU86017, a class III antiarrhythmic agent which blocks I(Kr), I(Ks), and I(Ca.L), suppressed VF by correcting the molecular changes on reperfusion. METHODS: Cardiomyopathy (CM) was produced by 0.4 mg/kg sc L-thyroxin for 10 d in rats, and subjected to 10 min coronary artery ligation/reperfusion on d 11. Expressions of the Ca2+ handling and ET system and calcium transients were conducted and CPU86017 was injected (4 mg/kg, sc) on d 6-10. RESULTS: A high incidence of VF was found on reperfusion of the rat CM hearts, but there was no VF before reperfusion. The elevation of diastolic calcium was significant in the CM myocytes and exhibited abnormality of the Ca2+ handling system. The rapid downregulation of mRNA and the protein expression of FKBP12.6 and SERCA2a were found on reperfusion in association with the upregulation of the expression of the endothelin-converting enzyme (ECE) and protein kinase A (PKA), in contrast, no change in the ryanodine type 2 receptor (RyR2), phospholamban (PLB), endothelin A receptor (ETAR), and iNOS was found. CPU86017 removed these changes and suppressed VF. CONCLUSION: Abrupt changes in the expression of FKBP12.6, SERCA2a, PKA, and ECE on reperfusion against ischemia, which are responsible for the rapid occurrence of VF, have been observed. These changes are effectively prevented by CPU86017.

The antihyperglycaemic activity of berberine arises from a decrease of glucose absorption.

The mechanism of action of berberine as an antihyperglycaemic agent was investigated in the Caco-2 cell line. Berberine was found to effectively inhibit the activity of disaccharidases in Caco-2 cells. It also decreased sucrase activity after preincubation with Caco-2 cells for 72 hours. However gluconeogenesis and glucose consumption of Caco-2 cells were not influenced. 2-Deoxyglucose transporting through Caco-2 cell monolayers was decreased by berberine but the effect was not statistically significant. These results suggest that the antihyperglycaemic activity of berberine is at least partly due to its ability to inhibit alpha-glucosidase and decrease glucose transport through the intestinal epithelium.