Polysaccharide-based emulsion gels for the prevention of postoperative adhesions and as a drug delivery system using 5-fluorouracil.

Postoperative tissue adhesion is a well-recognized and common complication. Despite ongoing developments in anti-adhesion agents, complete prevention remains a challenge in clinical practice. Colorectal cancer necessitates both adhesion prevention and postoperative chemotherapy. Accordingly, drug-loading into an anti-adhesion agent could be employed as a treatment strategy to maximize the drug effects through local application and minimize side effects. Herein, we introduce an anti-adhesion agent that functions as a drug delivery system by loading drugs within an emulsion that forms a gel matrix in the presence of polysaccharides, xanthan gum, and pectin. Based on the rheological analysis, the xanthan gum-containing emulsion gel formed a gel matrix with suitable strength and mucosal adhesiveness. In vitro dissolution tests demonstrated sustained drug release over 12 h, while in vivo pharmacokinetic studies revealed a significant increase in the Tmax (up to 4.03 times) and area under the curve (up to 2.62 times). However, most of the drug was released within one day, distributing systemically and raising toxicity concerns, thus limiting its efficacy as a controlled drug delivery system. According to in vivo anti-adhesion efficacy evaluations, the xanthan gum/pectin emulsion gels, particularly F2 and F3, exhibited remarkable anti-adhesion capacity (P < 0.01). The emulsion gel formulation exhibited no cytotoxicity against fibroblasts or epithelial cell lines. Thus, the xanthan gum/pectin emulsion gel exhibits excellent anti-adhesion properties and could be developed as a drug delivery system.

Preparation and characterization of lysozyme loaded liposomal dry powder inhalation using non-ionic surfactants.

Delivering protein drugs through dry powder inhalation (DPI) remains a significant challenge. Liposomes offer a promising solution, providing protection for proteins from external environment and controlled release capabilities. Furthermore, the use of non-ionic surfactants plays a crucial role in protecting the activity of proteins because of how the surfactants positioning themselves at the liquid-gas interface during the spray-drying process. In this study, lysozyme-loaded liposomal DPI formulations were prepared using various non-ionic surfactants, including polysorbate 80, poloxamer 188, poloxamer 407, and sucrose stearate. Lysozyme solution and 1,2-distearoyl-sn-glycero-3-phosphatidylcholine liposomes were subjected through high-pressure homogenization to form lysozyme-loaded liposomes. Formulations of homogenized lysozyme liposomes were spray-dried and further characterized. The particle size of reconstituted liposomal lysozyme DPI was from 129.5 to 816.9 nm. The formulations showed encapsulation efficiency up to 32.5% with zeta potential value of around - 30 mV, and spherical structures were observed. The aerosol dispersion performance of the dry powder inhalers was evaluated with emitted doses reaching up to 103% and fine particle fractions up to 28.4%. Significantly higher lysozyme activity was confirmed in formulation with drug to PS 80 ratio of 1: 0.5 w/w (92.1%) compared to that of formulation containing no surfactant (59.8%). The formulation stood out as the only formulation that maintained protein activity while demonstrating good aerosol performance.

Preparation of Apixaban Solid Dispersion for the Enhancement of Apixaban Solubility and Permeability.

(1) Background: Solid dispersion (SD) can help increase the bioavailability of poorly water-soluble drugs. Meanwhile, apixaban (APX)-a new anticoagulation drug-has low water solubility (0.028 mg/mL) and low intestinal permeability (0.9 × 10-6 cm/s across Caco-2 colonic cells), thus resulting in a low oral bioavailability of <50%; (2) Methods: To solve the drawbacks of conventional APX products, a novel SD of APX in Soluplus® was prepared, characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) spectroscopy techniques and evaluated for its solubility, intestinal permeability and pharmacokinetic performance. (3) Results: The crystallinity of the prepared APX SD was confirmed. The saturation solubility and apparent permeability coefficient increased 5.9 and 2.54 times compared to that of raw APX, respectively. After oral administration to the rats, the bioavailability of APX SD was improved by 2.31-fold compared to that of APX suspension (4) Conclusions: The present study introduced a new APX SD that potentially exhibits better solubility and permeability, thus increasing APX's bioavailability.

The efficacy and perioperative complications associated with lumbar spinal fusion surgery, focusing on geriatric patients in the republic of Korea.

OBJECTIVE: The purpose of this study was to examine the efficacy and perioperative complications associated with lumbar spinal fusion surgery, focusing on geriatric patients in the Republic of Korea. METHODS: We retrospectively investigated 485 patients with degenerative spinal diseases who had lumbar spinal fusion surgeries between March 2006 and December 2010 at our institution. Age, sex, comorbidity, American Society of Anesthesiologists (ASA) class, fusion segments, perioperative complications, and outcomes were analyzed in this study. Risk factors for complications and their association with age were analyzed. RESULTS: In this study, 81 patients presented complications (16.7%). The rate of perioperative complications was significantly higher in patients 70 years or older than in other age groups (univariate analysis, p=0.015; multivariate analysis, p=0.024). The perioperative complications were not significantly associated with the other factors tested (sex, comorbidity, ASA class, and fusion segments). Post-operative outcomes of lumbar spinal fusion surgeries for the patients were determined on the basis of MacNab's criteria (average follow up period : 19.7 months), and 412 patients (85.0%) were classified as having "excellent" or "good" results. CONCLUSION: Increasing age was an important risk factor for perioperative complications in patients undergoing lumbar spinal fusion surgery, whereas other factors were not significant. However, patients' satisfaction or return to daily activities when compared with younger patients did not show much difference. We recommend good clinical judgment as well as careful selection of geriatric patients for lumbar spinal fusion surgery.

GABAergic synaptic response and its opioidergic modulation in periaqueductal gray neurons of rats with neuropathic pain.

BACKGROUND: Neuropathic pain is a chronic and intractable symptom associated with nerve injury. The periaqueductal gray (PAG) is important in the endogenous pain control system and is the main site of the opioidergic analgesia. To investigate whether neuropathic pain affects the endogenous pain control system, we examined the effect of neuropathic pain induced by sacral nerve transection on presynaptic GABA release, the kinetics of postsynaptic GABA-activated Cl- currents, and the modulatory effect of µ-opioid receptor (MOR) activation in mechanically isolated PAG neurons with functioning synaptic boutons. RESULTS: In normal rats, MOR activation inhibited the frequency of GABAergic miniature inhibitory postsynaptic currents (mIPSCs) to 81.3% of the control without any alteration in their amplitude. In neuropathic rats, the inhibition of mIPSC frequency by MOR activation was 82.4%. The frequency of GABAergic mIPSCs in neuropathic rats was 151.8% of normal rats without any difference in the mIPSC amplitude. Analysis of mIPSC kinetics showed that the fast decay time constant and synaptic charge transfer of mIPSCs in neuropathic rats were 76.0% and 73.2% of normal rats, respectively. CONCLUSIONS: These results indicate that although the inhibitory effect of MOR activation on presynaptic GABA release is similar in both neuropathic and normal rats, neuropathic pain may inhibit endogenous analgesia in the PAG through an increase in presynaptic GABA release.

Cyclic AMP-mediated long-term facilitation of glycinergic transmission in developing spinal dorsal horn neurons.

cAMP is known to regulate neurotransmitter release via protein kinase A (PKA)-dependent and/or PKA-independent signal transduction pathways at a variety of central synapses. Here we report the cAMP-mediated long-lasting enhancement of glycinergic transmission in developing rat spinal substantia gelatinosa neurons. Forskolin, an adenylyl cyclase activator, elicited a long-lasting increase in the amplitude of nerve-evoked glycinergic inhibitory postsynaptic currents (IPSCs), accompanied by a long-lasting decrease in the paired-pulse ratio in immature substantia gelatinosa neurons, and this forskolin-induced increase in glycinergic IPSCs decreased with postnatal development. Forskolin also decreased the failure rate of glycinergic IPSCs evoked by minimal stimulation, and increased the frequency of glycinergic miniature IPSCs. All of these data suggest that forskolin induces the long-lasting enhancement of glycinergic transmission by increasing in the presynaptic release probability. This pre-synaptic action of forskolin was mediated by hyperpolarization and cyclic nucleotide-activated cation channels and an increase in intraterminal Ca(2+) concentration but independent of PKA. The present results suggest that cAMP-dependent signal transduction pathways represent a dynamic mechanism by which glycinergic IPSCs could potentially be modulated during postnatal development.

Presynaptic glycine receptors facilitate spontaneous glutamate release onto hilar neurons in the rat hippocampus.

Although glycine receptors are found in most areas of the brain, including the hippocampus, their functional significance remains largely unknown. In the present study, we have investigated the role of presynaptic glycine receptors on excitatory nerve terminals in spontaneous glutamatergic transmission. Spontaneous EPSCs (sEPSCs) were recorded in mechanically dissociated rat dentate hilar neurons attached with native presynaptic nerve terminals using a conventional whole-cell patch recording technique under voltage-clamp conditions. Exogenously applied glycine or taurine significantly increased the frequency of sEPSCs in a concentration-dependent manner. This facilitatory effect of glycine was blocked by 1 microM strychnine, a specific glycine receptor antagonist, but was not affected by 30 microM picrotoxin. In addition, Zn(2+) (10 microM) potentiated the glycine action on sEPSC frequency. Pharmacological data suggested that the activation of presynaptic glycine receptors directly depolarizes glutamatergic terminals resulting in the facilitation of spontaneous glutamate release. Bumetanide (10 microM), a specific Na-K-2C co-transporter blocker, gradually attenuated the glycine-induced sEPSC facilitation, suggesting that the depolarizing action of presynaptic glycine receptors was due to a higher intraterminal Cl(-) concentration. The present results suggest that presynaptic glycine receptors on excitatory nerve terminals might play an important role in the excitability of the dentate gyrus-hilus-CA3 network in physiological and/or pathological conditions.

Nitric oxide modulation of GABAergic synaptic transmission in mechanically isolated rat auditory cortical neurons.

The auditory cortex (A1) encodes the acquired significance of sound for the perception and interpretation of sound. Nitric oxide (NO) is a gas molecule with free radical properties that functions as a transmitter molecule and can alter neural activity without direct synaptic connections. We used whole-cell recordings under voltage clamp to investigate the effect of NO on spontaneous GABAergic synaptic transmission in mechanically isolated rat auditory cortical neurons preserving functional presynaptic nerve terminals. GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) in the A1 were completely blocked by bicuculline. The NO donor, S-nitroso-N-acetylpenicillamine (SNAP), reduced the GABAergic sIPSC frequency without affecting the mean current amplitude. The SNAP-induced inhibition of sIPSC frequency was mimicked by 8-bromoguanosine cyclic 3',5'-monophosphate, a membrane permeable cyclic-GMP analogue, and blocked by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, a specific NO scavenger. Blockade of presynaptic K(+) channels by 4-aminopyridine, a K(+) channel blocker, increased the frequencies of GABAergic sIPSCs, but did not affect the inhibitory effects of SNAP. However, blocking of presynaptic Ca(2+) channels by Cd(2+), a general voltage-dependent Ca(2+) channel blocker, decreased the frequencies of GABAergic sIPSCs, and blocked SNAP-induced reduction of sIPSC frequency. These findings suggest that NO inhibits spontaneous GABA release by activation of cGMP-dependent signaling and inhibition of presynaptic Ca(2+) channels in the presynaptic nerve terminals of A1 neurons.

Effect of nitric oxide on auditory cortical neurons of aged rats.

Age-related changes in the effects of nitric oxide (NO) on neurons of the auditory cortex have not been determined. We therefore evaluated the anatomical changes and neurophysiological characteristics of these neurons in rats as a function of age. The numbers of cresyl violet stained cells, the numbers and areas of NADPH-d-positive neuronal cell bodies, and their optical density, were measured in Sprague-Dawley rats aged 24 months (aged group) and 4 months (control group). The modulatory effects of NO on K(+) currents of acutely isolated rat auditory cortical neurons were also assessed. There were no between-group differences in the distribution patterns of glial cells and neurons, or in the numbers and areas of NADPH-d-positive neuronal cell bodies. However, the optical density of NADPH-d-positive neuronal cell bodies was significantly greater in the aged group than in the control group. In addition, voltage-gated K(+) currents of rat auditory cortical neurons were activated by increased levels of NO. As activation of the K(+) current likely suppresses neuronal excitability, age-associated increases in NO production can hinder the function of the acoustic center by inhibiting neuron excitability.

Zinc modulation of glycine receptors in acutely isolated rat CA3 neurons.

Glycine and GABA are the primary inhibitory neurotransmitters in the spinal cord and brain stem, with glycine exerting its physiological roles by activating strychnine-sensitive ionotropic receptors. Glycine receptors are also expressed in the brain, including the cortex and hippocampus, but their physiological roles and pharmacological properties are largely unknown. Here, we report the pharmacological properties of functional glycine receptors in acutely isolated rat CA3 neurons using conventional whole-cell patch clamp techniques. Both glycine and taurine, which are endogenous agonists of glycine receptors, elicited Cl(-) currents in a concentration-dependent manner. The glycine-induced current (I(Gly)) was inhibited by strychnine, picrotoxin or cyclothiazide in a concentration-dependent manner. At lower concentrations (0.01-1 microM), ICS-205,930 potentiated I(Gly), but at higher concentrations (>10 microM) it inhibited I(Gly). These pharmacological properties strongly suggest that CA3 neurons express functional strychnine-sensitive glycine receptors containing alpha2 subunits. Furthermore, at lower concentrations (1-30 microM), Zn(2+) potentiated I(Gly), but at higher concentrations (>100 microM) it inhibited I(Gly). Considering that Zn(2+) is synaptically co-released with glutamate from mossy fiber terminals that make excitatory synapses onto CA3 neurons, these results suggest that endogenous Zn(2+) modulation of these glycine receptors may have an important role in the excitability of CA3 neurons.

Adenosine A1 receptors inhibit GABAergic transmission in rat tuberomammillary nucleus neurons.

The adenosinergic modulation of GABAergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs) was investigated in mechanically dissociated rat tuberomammillary nucleus (TMN) neurons using a conventional whole-cell patch clamp technique. Adenosine (100 microM) reversibly decreased mIPSC frequency without affecting the current amplitude, indicating that adenosine acts presynaptically to decrease the probability of spontaneous GABA release. The adenosine action on GABAergic mIPSC frequency was completely blocked by 1 microM DPCPX, a selective A(1) receptor antagonist, and mimicked by 1 microM CPA, a selective A(1) receptor agonist. This suggests that presynaptic A(1) receptors were responsible for the adenosine-mediated inhibition of GABAergic mIPSC frequency. CPA still decreased GABAergic mIPSC frequency even either in the presence of 200 microM Cd(2+), a general voltage-dependent Ca(2+) channel blocker, or in the Ca(2+)-free external solution. However, the inhibitory effect of CPA on GABAergic mIPSC frequency was completely occluded by 1 mM Ba(2+), a G-protein coupled inwardly rectifying K(+) (GIRK) channel blocker. In addition, the CPA-induced decrease in mIPSC frequency was completely occluded by either 100 microM SQ22536, an adenylyl cyclase (AC) inhibitor, or 1 muM KT5720, a specific protein kinase A (PKA) inhibitor. The results suggest that the activation of presynaptic A(1) receptors decreases spontaneous GABAergic transmission onto TMN neurons via the modulation of GIRK channels as well as the AC/cAMP/PKA signal transduction pathway. This adenosine A(1) receptor-mediated modulation of GABAergic transmission onto TMN neurons may play an important role in the fine modulation of the excitability of TMN histaminergic neurons as well as the regulation of sleep-wakefulness.

5-HT1A receptor-mediated activation of a G-protein-coupled inwardly rectifying K+ current in rat medial preoptic area neurons.

The medial preoptic area plays an important role in the regulation of sexual behavior, and serotonin (5-hydroxytryptamine, 5-HT) exerts an inhibitory effect on sexual behavior by acting on the medial preoptic area region. This study was designed to clarify the inhibitory effect of 5-HT on the medial preoptic area neurons and to elucidate the electrophysiological mechanisms involved in the action of 5-HT. Superfusion of 100 nM 5-HT hyperpolarized the membrane potential and inhibited the action potential firing. When the membrane potential was stepped to various potentials, the inward K+ currents were potentiated in the presence of 100 nM 5-HT. When the concentration of K+ in the external solution was increased from 5 mM to 30 mM, 5-HT markedly potentiated the inward K+ currents. In the steady-state current-voltage relationship, the 5-HT-activated inward current was carried by K+ ions and showed characteristics typical of an inwardly rectifying K+ current. The 5-HT-activated K+ current was mimicked by a 5-HT1A receptor agonist, (+/-)-8-hydroxy-2-dipropylaminotetralin hydrobromide, and was reversibly blocked by a 5-HT1A receptor antagonist, 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine hydrobromide, but not by a 5-HT2 receptor antagonist, ketanserin. The 5-HT-activated K+ current was sensitively blocked by Ba2+, but not by 4-aminopyridine, and was completely suppressed by N-ethylmaleimide. These results indicate that 5-HT-induced hyperpolarization of the medial preoptic area neurons occurs as a result of activation of the G-protein-coupled inwardly rectifying K+ currents by 5-HT1A receptors.

Serotonergic modulation of GABAergic and glutamatergic synaptic transmission in mechanically isolated rat medial preoptic area neurons.

The medial preoptic area (MPOA) of the hypothalamus is critically involved in the regulation of male sexual behavior and has been implicated in several homeostatic processes. Serotonin (5-hydroxytryptamine, 5-HT) inhibits sexual behavior via effects in the MPOA, where there are high densities of 5-HT(1A) and 5-HT(1B) receptor subtypes. We used whole-cell recordings under voltage-clamp conditions to investigate the serotonergic modulation of gamma-aminobutyric acid (GABA)ergic and glutamatergic synaptic transmission in mechanically dissociated rat MPOA neurons with native presynaptic nerve endings. Spontaneous GABAergic miniature inhibitory postsynaptic currents (mIPSCs) in the MPOA were completely blocked by bicuculline. Serotonin reversibly reduced the GABAergic mIPSC frequency without affecting the mean current amplitude. Serotonergic inhibition of mIPSC frequency was mimicked by (+/-)-8-hydroxy-2-dipropylaminotetralin hydrobromide, a specific 5-HT(1A) receptor agonist, and blocked by 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine hydrobromide, a specific 5-HT(1A) receptor antagonist. 6-Cyano-7-nitroquinoxaline-2,3-dione completely blocked spontaneous glutamatergic miniature excitatory postsynaptic currents (mEPSCs) in the MPOA. Serotonin reversibly decreased the glutamatergic mEPSC frequency without affecting the mean current amplitude. Serotonergic inhibition of mEPSC frequency was mimicked by CGS 12066B, a specific 5-HT(1B) receptor agonist, and blocked by SB 216641, a specific 5-HT(1B) receptor antagonist. Stimulation of adenylyl cyclase with forskolin increased the frequencies of GABAergic mIPSCs and glutamatergic mEPSCs, and blocked the inhibitory effects of 5-HT. H-89, a selective protein kinase A (PKA) inhibitor, decreased the frequencies of GABAergic mIPSCs and glutamatergic mEPSCs, and blocked their reduction by 5-HT. These findings suggest that 5-HT reduces the frequency of GABAergic mIPSCs and glutamatergic mEPSCs through 5-HT(1A) and 5-HT(1B) receptor-mediated inhibition, respectively, of the PKA-dependent pathway in the presynaptic nerve terminals of MPOA neurons.

Anxiolytic-like effects of sinapic acid in mice.

Sinapic acid is a phenylpropanoid compound and is found in various herbal materials and high-bran cereals. With the exception of its antioxidant activities, the pharmacological properties of sinapic acid have been rarely reported. The purpose of this study was to characterize the putative anxiolytic-like properties of sinapic acid using an elevated plus-maze (EPM) and hole-board test. Control mice were orally treated with an equal volume of vehicle (10% Tween 80 solution), and positive control mice were treated with diazepam (1 mg/kg, i.p.). Sinapic acid (4 mg/kg, p.o.) significantly increased the percentages of time spent in the open arms of the EPM test (P<0.05). In the hole-board test, sinapic acid also significantly increased the number of head-dips at 4 mg/kg (P<0.05). In addition, the anxiolytic-like properties of sinapic acid examined in the EPM test were blocked by flumazenil or bicuculline, which are GABA(A) antagonists. Moreover, sinapic acid markedly potentiated GABA current in single cortical neurons in a dose-dependant manner, and reactive I(GABA) increased to 1.8 times at 1 muM of sinapic acid. These results suggested that sinapic acid is a prominent anxiolytic agent, and that its anxiolytic-like effects are mediated via GABA(A) receptors and potentiating Cl(-) currents.

The ameliorating effect of oroxylin A on scopolamine-induced memory impairment in mice.

Oroxylin A is a flavonoid and was originally isolated from the root of Scutellaria baicalensis Georgi., one of the most important medicinal herbs in traditional Chinese medicine. The aim of this study was to investigate the ameliorating effects of oroxylin A on memory impairment using the passive avoidance test, the Y-maze test, and the Morris water maze test in mice. Drug-induced amnesia was induced by administering scopolamine (1 mg/kg, i.p.) or diazepam (1 mg/kg, i.p.). Oroxylin A (5 mg/kg) significantly reversed cognitive impairments in mice by passive avoidance and the Y-maze testing (P<.05). Oroxylin A also improved escape latencies in training trials and increased swimming times and distances within the target zone of the Morris water maze (P<.05). Moreover, the ameliorating effects of oroxylin A were antagonized by both muscimol and diazepam (0.25 mg/kg, i.p., respectively), which are GABA(A) receptor agonists. Furthermore, oroxylin A (100 microM) was found to inhibit GABA-induced inward Cl(-) current in a single cortical neuron. These results suggest that oroxylin A may be useful for the treatment of cognitive impairments induced by cholinergic dysfunction via the GABAergic nervous system.

Developmental change of GABAergic postsynaptic current in rat periaqueductal gray.

The present study was designed to examine developmental changes of GABAergic spontaneous miniature inhibitory postsynaptic currents (mIPSCs) in periaqueductal gray (PAG) neurons mechanically isolated from young (12- to 18-day) and adult (8- to 12-week) rats. While the frequency of mIPSCs was similar, the current amplitude in adult rats was significantly smaller than in young rats. In the study of mIPSC kinetics, all kinetic parameters except for the fast decay time in adult rats were smaller or shorter than in the case of young rats. The present study demonstrates that a decrease in the amplitude of GABAergic mIPSC during development may result from a decrease in the GABA contents of synaptic vesicles and from changes in the kinetics of postsynaptic GABA-activated Cl- channels.

Opioid inhibition of GABAergic neurotransmission in mechanically isolated rat periaqueductal gray neurons.

The descending pain control system is activated by opioid peptides mainly at the midbrain periaqueductal gray (PAG). Although activation of presynaptic opioid receptors has been reported to inhibit gamma-aminobutyric acid (GABA) release, the exact electrophysiological mechanisms are controversial. To elucidate the mechanisms involved in the opioid modulation of presynaptic GABA release, we isolated single PAG neurons with functionally intact synaptic terminals by a mechanical dissociation in the absence of enzyme. With the conventional whole-cell recording mode under the voltage-clamp conditions, the spontaneous miniature inhibitory postsynaptic currents (mIPSCs) were recorded. Bicuculline completely and reversibly blocked mIPSCs. A specific mu-opioid agonist, [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO), reversibly reduced the frequency of mIPSCs without any alteration of amplitude. The inhibitory effect of DAMGO was blocked by N-ethylmaleimide. Blockade of presynaptic Ca(2+) influx by cadmium or depletion of extracellular Ca(2+) did not alter the DAMGO inhibition. In addition, K(+) channels blockers, Ba(2+) or 4-aminopyridine, did not affect the DAMGO effect. The present study indicates that activation of presynaptic mu-opioid receptors coupled to G-proteins inhibits GABA release through unknown intracellular mechanisms downstream of Ca(2+) influx.

Activation of protein kinase C antagonizes the opioid inhibition of calcium current in rat spinal dorsal horn neurons.

Spinal dorsal horn (SDH) is one of important regions in both nociceptive transmission and antinociception. Opioid peptides produce analgesia via regulation of neurotransmitter release through modulation of voltage-dependent Ca(2+) channel (VDCC) in neuronal tissues. The modulatory effect of micro-opioid receptor (MOR) activation on VDCC was investigated in acutely isolated rat SDH neurons under the conventional whole-cell patch-clamp recording mode. The Ba(2+) current passing through VDCC was reversibly inhibited by a MOR agonist, [D-Ala(2),N-MePhe(4),Gly(5)-ol]-enkephalin (DAMGO, 1 microM). Among 108 SDH neurons tested, VDCC of 39 neurons (36%) were inhibited by MOR activation, while other 69 neurons (64%) were not affected. The L-, N-, P/Q-, and R-type VDCC components shared 58.4+/-18.9%, 29.3+/-12.1%, 8.7+/-7.2%, and 3.4+/-4.8% of the total VDCC, respectively. Among VDCC subtypes inhibited by MOR activation, L- and N-types were 61.4+/-12.8% and 30.7+/-14.4%, respectively, while both P/Q- and R-types were 7.9+/-11.8%. A depolarizing pre-pulse increased the amplitude of VDCC and suppressed most of the inhibitory effect of MOR activation. Application of 1 microM phorbol-12-myristate-13-acetate completely antagonized the inhibitory effect of MOR activation without any alteration of basal VDCC amplitude. In contrast, the response of MOR activation was not altered by application of 4-alpha-phorbol (1 microM), 2-[3-Dimethylaminopropyl]indol-3-yl]-3-(indol-3-yl) maleimide (GF109203X, 1 microM), forskolin (1 microM), N-(2-[p-Bromocinnamylamino]ethyl)-5-isoquinolinesulfonamide hydrochloride (H-89, 1 microM). These results indicate that activation of MOR coupled to G-proteins inhibits VDCC, and that this G-protein-mediated inhibition is antagonized by PKC-dependent phosphorylation.

Electroacupuncture enhancement of natural killer cell activity suppressed by anterior hypothalamic lesions in rats.

BACKGROUND/OBJECTIVE: Neuroendocrine hormones are derived from the hypothalamus. The central nervous system, particularly the hypothalamus, is capable of modulating the cytolytic activity of adherent natural killer (NK) cells. In addition, electroacupuncture (EA) stimulation of the Zusanli (ST36) acupoint enhances splenic NK cell and cytokine activities in rats. However, it is still unclear whether the anterior hypothalamus affects this immunomodulation. Therefore, the aim of the present study was to examine the effect of EA stimulation at the Zusanli acupoint on the NK cell activity modulated by an anterior hypothalamic area lesion. METHODS: Male Sprague-Dawley rats were used. Lesions were placed by means of a direct current through a concentric electrode. The electric acupuncture stimulation was delivered for 30 min per each experiment at the right ST36 acupoint with an electrical stimulator. The NK cell activity of the spleen was measured by a fluorescence assay. RESULTS: The NK cell activity was significantly reduced on the 2nd day after the lesion, but was restored to that of the sham group by the 7th day. However, when EA was applied for 2 days after the operation, the NK cell activity of the lesion group was restored to that of the sham group. After 7 days of EA, the NK cell activity of the lesion group was slightly higher than that of the sham group. CONCLUSION: From these results, we can suggest that EA enhances or restores the NK cell activity suppressed by an anterior hypothalamic area lesion.