Injections Of Amino Acids Research Articles

Amino acids are more important insulinotropins than glucose in a teleost fish, barfin flounder ( Verasper moseri)

The insulinotropic effects of eighteen l-amino acids, two d-amino acids, and glucose were investigated to evaluate the priority of those as stimulators of insulin secretion in barfin flounder ( Verasper moseri). This is also the first step in characterizing the insulinotropin-sensing molecule. After intramuscular injection of amino acids or glucose at doses of 3.50 and 1.75 mmol/kg body weight, plasma was collected periodically to determine plasma insulin level. Twelve amino acids and glucose showed insulinotropic effects. Four l-amino acids (Arg, Ala, Met, Ser) produced significantly higher integrated levels of plasma insulin (12.4–34.8 ng/ml) than glucose (average: 4.7 ng/ml) during 3 h after injection. d-Amino acids (Arg, Ala) showed no activity. This indicates that many amino acids have strong insulinotropic activities and supports a classic idea, which is well known but has not been confirmed, that amino acids rather than glucose are the important insulinotropins in fish. This study also indicates that the insulinotropic activity of amino acids is restricted to l-amino acids and establishes which amino acids are the strongest stimulators of the insulinotropin sensor in barfin flounder. Co-injection of insulin and l-Thr, l-Ala, or glucose produced a hypoglycemic and hypoaminoacidemic state, indicating that insulin can lower blood amino acid level as well as blood sugar level. This study suggests that insulin plays a more important role than glucose in the regulation of blood l-amino acid metabolism, at least in flounder.

Effect of compound branch chain amino acid injection on nutritional support in patients after radical resection for colorectal cancer

To evaluate the effect of compound branch chain amino acid(BCAA) injection on nutritional support in patients after radical resection for colorectal cancer. Fifty patients with radical resection for colorectal cancer were randomly divided into two groups, and received compound branch chain amino acid (n=25) or compound amino acid(n=25) as control per day from postoperative day(POD)1 to POD 7. The levels of total protein, albumin, pre-albumin, transferring, nitrogen balance and complications were compared between the two groups. On POD 8, the levels of albumin, pre- albumin, transferring were (36.12+/-3.16)g/L, (237.10+/-37.29)mg/L, and (2.18+/- 1.34)g/L in study group, and (30.61+/-3.55)g/L, (191.73+/-27.60)mg/L, and (1.71+/-0.84)g/L respectively in the control group(all P< 0.05). Nitrogen balance increased significantly from POD5, and increased to normal on POD 6 in study group, significantly higher than that in the control group (9.91+/-6.53 vs - 9.73+/-11.21, P=0.024). The complication rate of incision infection and delayed healing was 8.3% in study group, significantly lower than 38.1% in the control group(P< 0.05). Compared with compound amino acid, compound branch chain amino acid injection can reduce proteolysis, correct negative nitrogen balance and promote wound healing.

Derivatization of Hydrophobic Amino Acids in Nonaqueous Media and Separation by Nonaqueous Capillary Electrophoresis with Laser-Induced Fluorescence Detection

A method of nonaqueous capillary electrophoresis was established for the separation and determination of alanine, phenylalanine, isoleucine and valine after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1, 3-diazol in nonaqueous media. The derivatization and separation conditions were optimized. The optimum derivatization conditions were 70 min for the reaction time, 55 °C for the reaction temperature and 20 mM ammonium acetate in methanol for the derivatization buffer. The most suitable running buffer was composed of 60 mM ammonium acetate, 10% acetonitrile in methanol with a fused-silica capillary column (47 cm × 75 µm i.d.), 20 kV applied voltage and 20 °C capillary temperature. The correlation coefficients were better than 0.995 in the investigated concentration ranges. The relative standard deviation (R.S.D.) (n = 5) of the migration times and peak areas were 2.0–4.3% and 1.9–4.5%, respectively. The method was applied to the determination of four compounds in two compound amino acid injections, with the exception of phenylalanine, the recoveries for the other three compounds ranging between 88–116%.

Effect of In ovo Injection of Critical Amino Acids on Pre- and Post-hatch Growth, Immunocompetence and Development of Digestive Organs in Broiler Chickens

Two experiments were conducted to standardize in ovo injection of amino acids (AA) and to evaluate the effect of in ovo injection of limiting AA(s) on pre and post hatch growth performance, immune response and development of digestive organs. Combinations of essential and non-essential amino acids (Lys+Arg, Lys+Met+Cys, Thr+Gly+Ser, Ile+Leu+Val and Gly+Pro) were injected into 50 eggs in each treatment group at 14 d of embryonic age. Standardization of injection site, needle length and embryonic age revealed that when AA were injected in to the broad end of the egg with a 11 mm needle and at the narrow end with a 24 mm needle both at the 7 th and 14 th d of incubation there was poor hatchability. However, better hatchability was recorded when the AA were injected in the narrow end of the egg with a 11 mm needle and in the broad end with a 24 mm needle on the 14 th d of incubation. The chick to egg weight ratio was higher (p<0.018) when AA were injected on the 14 th d of incubation. When a combination of amino acids were injected a 63.6 or 63.2 g difference in body weight of bird at 21 d was recorded between uninjected control and Ile+Leu+Val or Gly+Pro group, respectively. Higher feed intake (p<0.047) was recorded in the AA injected groups and feed conversion ratio (FCR) was numerically better in Gly+Pro, Lys+Met+Cys AA injected groups than in the uninjected control. Significantly higher immune response to cell mediated (p<0.033) and humoral (p<0.002) immunity was observed in in ovo amino acid injected birds, especially in Lys+Met+Cys, Thr+Gly+Ser or Ile+leu+Val groups. The digestive organ weights at 21 d did not differ between specific AA injected groups and the uninjected control. In ovo injected amino acids may act as immunomodulators and their role in gastrointestinal development needs further research. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 4 : 524-531)

Method for on-line derivatization and separation of aspartic acid enantiomer in pharmaceuticals application by the coupling of flow injection with micellar electrokinetic chromatography

A novel, easy and accurate capillary electrophoresis (CE) coupled with flow injection (FI) method for the separation and determination of aspartic acid (Asp) enantiomers by on-line derivatization had been developed, and it had been applied to the real sample for the first time. The derivatization reagents were o-phthalaldehyde (OPA) and mercaptoethanol (ME), which were obtained easily, the chiral selector was β-cyclodextrin (β-CD), the micellar chemical was sodium dodecyl sulfate (SDS), and the modifier was methanol. By on-line derivatization, aspartic acid enantiomers were automatically and reproducibly converted to the ultraviolet (UV)-absorbing diastereoisomer derivates, which were separated by micellar electrokinetic chromatography (MEKC). According to the factors affecting the separation and sensitivity of aspartic acid enantiomer and other amino acids in the real sample, the pH value and concentration of the buffer, the concentration of β-CD and SDS, the volume percentage of the methanol (v/v) in the buffer, the applied voltage and the conversion time were selected as the investigating variates. Under the investigated separation conditions, d-aspartic acid ( d-Asp), l-aspartic acid ( l-Asp) and other four amino acids achieved the baseline separation in not only the standard mixture of amino acids but also the real sample (Compound Amino Acid Injection (6AA)). The repeatability (defined as relative standard deviation (RSD), n = 5) was 4.0% and 4.0% with peak area evaluation, and 4.2% and 3.7% with peak height evaluation for d-Asp and l-Asp in the real sample. Recovery at added standard levels of 1.0, 3.0 and 6.0 mM was 92%, 104% and 109%, respectively.

Effect of compound branch chain amino acids injection (Aminic) on protein metabolism in patients with radical resection of cardiac carcinoma

To evaluate the effect of compound branch chain amino acids injection (Aminic) on protein metabolism in patients with radical resection of cardiac carcinoma. Eighty patients with radical resection of cardiac carcinoma were randomly divided into two groups:study group (40 cases) with compound branch chain amino acids injection (Aminic), and control group(40 cases) with amino acids(MPR- F). The patients received total parenteral nutrition with equal calorie and nitrogen from 1st-7th days after operation by central or peripheral vein with infusing time over 12 hours per day. The change of body weight was observed. The serum levels of total protein, albumin,pre-albumin,transferring, and fibronectin were measured. The body weight was decreased in the two groups after operation, while compared with the study group,the body weight was significantly decreased in the control group (P=0.0250). The positive nitrogen balance recovered two days earlier in study group than that in the control group. Decrease of total protein,albumin were more severe in the control group than those in study group (P=0.0446,P=0.0314 respectively). Compared with the control group,the level of Valine was increased (P=0.0073),and the level of Arginine was decreased more obviously in the study group (P= 0.0212). The compound branch chain amino acids injection (Aminic) is more beneficial for patients with radical resection of cardiac carcinoma to correct negative nitrogen balance,it can also inhibit decomposition of muscles protein,and improve nutritional conditions.

Multiple neurotransmitter receptors contribute to the spinal Fos expression

The aim of this study is to identify the receptors which could potentially mediate the activation of c-Fos. Therefore, the effects of neurotransmitter receptor agonists in the activation of c-Fos in spinal neurons were studied by intrathecal injection of excitatory amino acid (EAA) receptor agonists: N-Methyl- d-Aspartate (NMDA), ( S)-α-Amino-3-Hydroxy-5-Methyl-4-Isoxazolepropionic acid (AMPA), 2-Carboxyl-3-carboxmethyl-4-isopropenylpyMidine (Kainic acid, KA), (1S-3R)-1-Aminocyclopentane-1, 3-dicarboxylacid (ACPD), and substance-P receptor (neurokinin-1) agonist, [Sar 9, Met (O 2) 11] SP (SarMet-SP). All drugs tested activated the production of c-Fos in spinal dorsal horn neurons. AMPA was found as the most potent agonist tested producing market production of c-Fos particularly in neurons of lamina II at doses of 10 pM per 10-μl injection. At this dose, other agonists were relatively ineffective. At higher doses, AMPA significantly increased the activated cells. NMDA significantly increased c-Fos production to a marked extent only at doses above 10 nM per 10-μl injection. KA and ACPD were least potent of the excitatory amino acid agonists. Injection of SarMet-SP at doses of 1 nM activated Fos selectively in neurons of lamina I. A dose-dependent increase in number of c-Fos-positive cells was observed for AMPA, KA, ACPD, and SarMet-SP, whereas NMDA gave a very strong expression after a high dose with no dose dependency. These finding suggest that multiple neurotransmitter receptors lead to c-Fos production in spinal neurons.

Summary of the American College for Advancement in Medicine November 2004 Conference on Emerging Concepts in Immunology

Summary of the American College for Advancement in Medicine November 2004 Conference on Emerging Concepts in Immunology

Microchip capillary electrophoresis with electrochemical detection of thiol-containing degradation products of V-type nerve agents.

A microchip protocol for the capillary electrophoresis separation and electrochemical detection of thiol-containing degradation products of V-type nerve agents is described. The microchip assay relies on the derivatization reaction of 2-(dimethylamino)ethanethiol (DMAET), 2-(diethylamino)ethanethiol (DEAET), and 2-mercaptoethanol (ME) with o-phthaldialdehyde in the presence of the amino acid valine along with amperometric monitoring of the isoindole derivatives. Both off-chip and on-chip derivatization reactions have led to highly sensitive and rapid detection of the thiol degradation products. Various parameters influencing the derivatization, separation, and detection processes were examined and optimized. These include the amino acid co-reagent, reagent-mixing ratio, reaction time, injection time, separation voltage, and detection potential. The chip microsystem offers a rapid (<4 min) simultaneous detection of micromolar concentrations of DMAET, DEAET, and ME. Linear calibration plots were observed for the V-type nerve agent thiol degradation products, along with good stability and reproducibility (RSD < 8.0%). Detection limits of 5 and 8 microM were obtained for the off-chip reaction of DMAET and DEAET, respectively, following a 2-s injection. The suitability for assays of environmental matrixes was demonstrated for the determination of DMAET and DEAET in untreated tap and river water samples. The favorable analytical performance makes the new microfluidic device attractive for addressing the needs of various security scenarios.

Microemulsion electrokinetic chromatography with laser-induced fluorescence detection: as tested with amino acid derivatives.

Over a decade ago, microemulsion electrokinetic chromatography was introduced as a novel mode of capillary electrophoresis. However, there has not been publication on the combination of microemulsion electrokinetic chromatography with laser-induced fluorescence detection. In this paper, a preliminary method using microemulsion eletrokinetic chromatography combined with laser-induced fluorescence detection and second derivative electrophoregram was established as a sensitive and selective assay for separation and determination of nine amino acids after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1, 3-diazol. The derivatization and separation conditions were optimized. In the investigated concentration ranges correlation coefficients were better than 0.995. The relative standard deviation (n = 5) of the migration times and peak heights were 0.56-0.76 and 2.21-7.15%, respectively. The detection limits (S/N = 3) were at a neaomolar level (0.32-2.20 nM). The method was applied for the analysis of compound amino acid injection and a Chinese traditional herbal medicine. The recoveries were 95.9-107.9%.

Comparison between broilers and layers for growth and protein use by embryos

Three experiments were conducted to compare the growth and protein utilization of embryo between broilers and layers. In experiments 1 and 2, the average weight of eggs was the same for broilers and layers. Nothing or an amino acid (AA) solution was injected into the eggs of broilers at d 7 of incubation, and the plasma AA concentration of newly hatched chicks was determined in broilers in experiment 1. In experiment 2, the same treatments as experiment 1 were used on layer breeder eggs. Plasma Tau, Thr, and Lys concentrations of hatched chicks increased when AA solution was injected in broilers breeder eggs (P < 0.05) but not in layers (P > 0.05). The AA ratio to Lys was reduced by AA injection in broilers but not in layers. In experiment 3, weights of embryos and egg were recorded, and CP contents were analyzed over time during incubation (d 0, 7, 14, and 19 of incubation) in broilers and layers using eggs of the same weight. There were no differences in the weights and CP contents of embryos and eggs from broilers and layers. On d 14 and 19 of incubation, weights and CP contents of embryo were higher in broilers than layers (P < 0.05). These results suggested that the egg protein content might be adequate for hatching but insufficient for maximum growth of embryos from broilers.

Electrocatalysis of Tryptophan at Multi-Walled Carbon Nanotube Modified Electrode

Acid-treated multi-walled carbon nanotubes (MWNTs) were immobilized on the surface of a glassy carbon electrode to form an MWNT-modified electrode. The electrocatalytic response of the modified electrode towards tryptophan (Trp) was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results demonstrated that the modified electrode exhibited a high degree of catalytic activity towards the oxidation of Trp. An oxidation peak was obtained in Trp solution at the MWNT-modified electrode. Compared with a bare electrode, the peak current had obviously increased, and the peak potential had shifted in a negative direction. However, under the same conditions, no response was observed for other amino acids. The oxidation peak currents were proportional linearly to the concentration of Trp, a property which could be utilized to detect Trp. The determination conditions, such as the concentration, the composition and the pH values of the supporting electrolyte, accumulation time, as well as scan rate etc. were optimized. Under the chosen conditions, the DPV peak current is linear to the concentration of Trp in the range of 2.5 × 10−7 to 1.0 × 10−4 mol L−1, and the detection limit is 2.7 × 10−8 mol L−1. Moreover, the detection is free of interference from other amino acids. The modified electrode has been successfully applied to determine the concentration of Trp in composite amino acid injections, and it displays excellent repeatability and higher sensitivity.

A capillary electrophoresis detection scheme for underivatized amino acids based on luminol–BrO − chemiluminescence system

A novel chemiluminescence (CL) detection scheme has been developed for detecting underivatized amino acids following capillary electrophoresis (CE) separation. This detection was based on the inhibitory effect of amino acids on the CL reaction between luminol and BrO − in alkaline aqueous solution. Detection of amino acids was accomplished with a borate-based background electrolyte at pH 9.2. The luminol was used as a component of the separation carrier electrolyte. Parameters affecting CE–CL separation and detection, such as the pH value, the concentration of electrolyte and CL reagent on the resolution were optimized. The relative standard deviation for the analysis of amino acids was less than 1.5% for the migration time and 4% for the peak height. The mass limits of detection were from 7 to 144 fmol for the 7 amino acids. This method has been applied of 7 amino acids in amino acid injection.

Acute Uremia Produced in Rats by Nephrotoxic Chemicals Is Alleviated by Protein Deficient Diet

Rats injected with mercuric chloride develop an acute renal tubular necrosis with uremia, which is frequently lethal. Pretreatment for 3 or 7 days with a protein-free diet reduces the mortality, the clinical signs (tremor), and the severity of renal tubular necrosis, and ameliorates the uremic chemical findings in the serum. Similar results followed injection of a nephrotoxic amino acid, d-serine, after pretreatment with a protein-free diet. Indirect evidence suggests that induction of metallothionein may be involved, at least in the experiments with mercury. Acute uremia produced by nephrotoxic chemicals may be useful for further studies of the role of nutrition in uremia, while avoiding the surgical procedures and prolonged observations required for the “remnant kidney” models.

Use of Wheat Gluten as Clarifying Agent of Musts and White Wines

The ventral striatum is considered an interface between limbic and motor systems. We followed the orbital and medial prefrontal circuit through the monkey basal ganglia by analyzing the projection from this cortical area to the ventral striatum and the representation of orbitofrontal cortex via the striatum, in the globus pallidus and substantia nigra. Following injections of Lucifer yellow and horse radish peroxidase into the medial ventral striatum, there is a very densely labeled distribution of cells in areas 13a and 13b, primarily in layers V and VI, and in medial prefrontal areas 32 and 25. Injections into the shell of the nucleus accumbens labeled primarily areas 25 and 32. The reaction product in the globus pallidus and the substantia nigra supports previous studies demonstrating that efferent projections from the ventral striatum are represented topographically in the ventral pallidum and nontopographically in the substantia nigra, pars compacta. Tritiated amino acid or PHA-L tracer injections into orbitofrontal cortex produce dense patches of terminal labeling along the medial edge of the caudate nucleus and the dorsal part of the nucleus accumbens. These results demonstrate that the orbital prefrontal cortex projects primarily to the medial edge of the ventral striatum and to the core of the nucleus accumbens. The arrangement of terminals in the globus pallidus and substantia nigra show two different patterns. Thus, the orbital and medial prefrontal cortex is represented in a confined region of the globus pallidus but throughout an extensive area of the dorsal substantia nigra. Terminals are extensive throughout the region of the dopaminergic neurons, suggesting that this input may influence a wide area of both the striatum and frontal cortex.

The Needle Bore Diameter for In Ovo Amino Acid Injection Has no Effect on Hatching Performance in Broiler Breeder Eggs.

The objective of this study was to determine if the bore diameter of needles used for in ovo injection of amino acids (AA) would affect subsequent chick hatchability. In Experiment 1, needles of different bore diameter were inserted into the egg. In Experiment 2, needles of different bore diameter were used to administer an AA solution that is identical to the AA pattern of the whole egg protein. In both experiments, 27, 24, 22, 20, and 18 gauge needles were tested. Needles were inserted to a depth of 13 mm in both experiments. Non-injected eggs were served as control in each experiment. Needle bore diameter did not affect (P<0.05) hatchability or body weight (BW) of hatched chicks in either experiment.

Optimum Site for In Ovo Amino Acid Injection in Broiler Breeder Eggs

Three experiments were conducted to evaluate the effect of differences in in ovo amino acid (AA) injection sites in broiler breeder eggs on subsequent hatchability and BW of chicks. In Experiment 1, an AA solution was injected into eggs with 13-mm or 19-mm, 27-ga needles. Uninjected eggs served as controls. Hatchability was decreased (P < 0.05) in eggs receiving AA injections with the 19-mm needle in comparison to the control and 13-mm-injected groups. However, BW of chicks increased (P < 0.05) relative to pre-incubational egg weight by AA injection with the 13-mm needle. In order to evaluate the in ovo location of AA injections from Experiment 1, India ink was injected into eggs in Experiment 2 with a 13-or 19-mm needle. Immediately after injection, the air cell end of the egg was windowed in order to observe effects of injection site. Windowing of eggs was accomplished by removing a piece of the eggshell over the air cell and the underlying membrane at Day 7 of incubation. The amount of injected India ink was higher in the extra-embryonic coelom in eggs treated by both needles. However, the occurrence of India ink in the extra embryonic coelom was higher (P < 0.05) in the group injected with AA solution using a 13-mm needle as compared to that after injection using a 19-mm needle. The observation of India ink in the amniotic cavity was higher (P < 0.05) in the group injected with AA solution using a 19-mm needle rather than that using a 13-mm needle. In Experiment 3, treatments consisted of control (uninjected eggs) or windowed eggs. Windowed eggs received AA to the chorioallantoic membrane, the yolk, extra-embryonic coelom, or amniotic cavity at Day 7 of incubation. Hatchability was reduced, but chicks hatched when eggs were windowed and when AA were injected into the yolk sac or extra-embryonic coelom. However, chicks did not hatch when AA were administered to the chorioallantoic membrane or into the amniotic cavity. These results suggest that the best AA injection sites in ovo may be the yolk and extra-embryonic coelom.

Embryo Growth and Amino Acid Concentration Profiles of Broiler Breeder Eggs, Embryos, and Chicks After In Ovo Administration of Amino Acids

Two experiments were conducted to evaluate the effect of in ovo amino acid (AA) injections in broiler breeder eggs on AA utilization of embryos. All AA used in these experiments were pure crystalline AA in free-base form. Treatments in Experiment 1 comprised 1) control eggs (no injection), 2) 0.5 mL sterile-distilled water injected eggs, and 3) eggs injected with an AA solution suspended in 0.5 mL sterile-distilled water. Injections were administered into the yolk at Day 7 of incubation. At hatch, chicks were killed and bled, and plasma AA concentration was determined. Plasma AA concentration of hatched chicks decreased (P < 0.05) when water was injected. In addition, all AA from eggs injected with AA, except Glu and Lys, were decreased (P < 0.05) at hatch as compared to control eggs. However, AA pattern was not affected by in ovo water injection, but the AA ratio to Lys was reduced by in ovo AA injection.Experiment 2 was conducted to evaluate whole internal egg AA concentrations over incubation time in the presence or absence of in ovo AA administration. Treatments in Experiment 2 comprised 1) control eggs (no injection), and 2) eggs injected with a AA solution at Day 7 of incubation. The AA contents of embryo, yolk, albumen, and allantoic and amnion fluids were analyzed over time during incubation (Days 0, 7, 14, and 19 of incubation). On Day 14 of incubation, there were no differences in AA contents of all tissues between the control group and the group injected with AA on Day 7 of incubation. On Day 19 of incubation, AA contents of embryo, yolk, albumen, and allantoic and amnion fluids were increased (P < 0.05) as mediated by in ovo administration of AA at Day 7 of incubation. These results suggest that in ovo administration of AA may increase AA concentrations in chicken embryos and other egg contents.

The role of amino acids in the regulation of hydrogen sulfide production during ultradian respiratory oscillation of Saccharomyces cerevisiae.

We previously demonstrated that periodic H2S production during aerobic continuous culture of Saccharomyces cerevisiae resulted in ultradian respiratory oscillation, and that H2S production was dependent on the activity of sulfate uptake and the level of sulfite. To investigate the mechanism of regulation of the sulfate assimilation pathway and of respiratory oscillation, several amino acids were pulse-injected into cultures during respiratory oscillation. Injection of sulfur amino acids or their derivatives perturbed respiratory oscillation, with changes in the H2S production profile. Four major regulators of H2S production in the sulfate assimilation pathway and respiratory oscillation were identified: (1) O-acetylhomoserine, not O-acetylserine, as a sulfide acceptor, (2) homoserine/threonine as a regulator of O-acetylhomoserine supply, (3) methionine/S-adenosyl methionine as a negative regulator of sulfate assimilation, and (4) cysteine (or its derivatives) as an essential regulator. The results obtained after the addition of DL-propargylglycine (5 microM and 100 microM) and cystathionine (50 microM) suggested that the intracellular cysteine level and cystathionine gamma-lyase, rather than methionine/S-adenosylmethionine, play an essential role in the regulation of sulfate assimilation and respiratory oscillation. Based on these results and those of our previous reports, we propose that periodic depletion of cysteine (or its derivatives), which is involved in the detoxification of toxic materials originating from respiration, causes periodic H2S production.

Effect of combined treatment with imipramine and amantadine on the immunological parameters of rats subjected to the forced swimming test

Metabotropic glutamate receptors (mGluRs) are expressed abundantly in the spinal cord and have been shown to play important roles in the modulation of nociceptive transmission and plasticity. In this study, the involvement of metabotropic glutamate receptor 5 (mGluR5) in the nociceptive response induced by intrathecal injection (i.t.) of excitatory aminoacids, substance P (SP), bradykinin (BK) and cytokines in mice was demonstrated. The administration of 2-methyl-6-(phenylethynyl)-pyridine (MPEP; 10–50 nmol/site, i.t.) caused a significant inhibition in the nociceptive response induced by glutamate and trans-ACPD with maximal inhibitory effects of 36 ± 7% and 56 ± 5%, respectively. MPEP completely failed to affect the nociception induced by α-amino-3-hydroxy-5-mehtyl-4-isoxazolepropionic acid (AMPA; 135 pmol/site), kainate (110 pmol/site) and N-methyl-d-aspartate (NMDA; 450 pmol/site). MPEP also reduced the nociceptive response induced by SP (135 ng/site, i.t.), BK (0.1 µg/site), tumor necrosis factor-alpha (TNF-α; 0.1 pg/site) and interleukin-1beta (IL-1β; 1 pg/site) with maximal inhibitions of 29 ± 5%, 37 ± 5%, 83 ± 3% and 88 ± 1%, respectively. Together, these results indicate the involvement of mGluRs, more specifically of subtype-5, in the nociceptive response induced by i.t. injection of excitatory aminoacids, SP, BK and cytokines in mice.