Comparative pharmacokinetics of a fixed-dose combination vs concomitant administration of telmisartan and S-amlodipine in healthy adult volunteers.

OBJECTIVE: This study compared the pharmacokinetic (PK) and safety profiles of a fixed-dose combination (FDC) formulation of telmisartan and S-amlodipine with those of concomitant administration of the two drugs. MATERIALS AND METHODS: This was an open-label, randomized, crossover study in healthy male Koreans. All subjects were administered an FDC tablet containing 40 mg telmisartan and 5 mg S-amlodipine and were also coadministered the same dose of both drugs given separately. The crossover study design included a 14-day washout period between the two treatments. Blood samples were collected up to 168 h following drug administration. The plasma concentrations of telmisartan and S-amlodipine were determined by liquid chromatography tandem mass spectrometry. PK parameters and plasma concentration-time curves were compared. Safety was assessed by measuring vital signs, clinical laboratory tests, physical examinations, and patient interviews. RESULTS: The geometric mean ratios and 90% CIs for the maximum plasma concentration (Cmax) and area under the curve from time zero to the last sampling time (AUCt) were 0.8782 (0.8167-0.9444) and 0.9662 (0.9210-1.0136) for telmisartan and 1.0069 (0.9723-1.0427) and 1.0324 (0.9969-1.0690) for S-amlodipine, respectively. A total of 36 adverse events (AEs) were reported by 23 subjects, but no statistical differences were observed between the two treatments. The most frequently reported AE was a mild-to-moderate headache that was generally self-limiting. CONCLUSION: For both telmisartan and S-amlodipine, the Cmax and AUCt 90% CIs were between ln (0.8) and ln (1.25). These results suggest that the FDC formulation is pharmacokinetically bioequivalent and has a similar safety profile to the coadministration of these drugs.

Pomegranate juice does not affect the disposition of simvastatin in healthy subjects.

Previous in vitro and in vivo investigations reported controversial results for the inhibitory potential of pomegranate on Cytochrome P450 (CYP) 3A activity. This study evaluated the effect of pomegranate juice on the disposition of simvastatin, a CYP3A4 substrate, and simvastatin acid, its active metabolite, compared with grapefruit juice in healthy subjects. A single oral pharmacokinetic study of 40 mg simvastatin was conducted as a three-way crossover (control, pomegranate, and grapefruit juices) in 12 healthy male subjects. The subjects took pomegranate or grapefruit juice three times per day for 3 days (900 mL/day) and on the third day, the pharmacokinetic study was executed. Blood samples were collected to 24 h post-dose and the pharmacokinetic parameters of simvastatin and simvastatin acid were compared among the study periods. In the period of grapefruit juice, the mean C max and AUCinf of simvastatin [the geometric mean ratio (90 % CI) 15.6 (11.6-21.0) and 9.1 (6.0-13.7)] were increased significantly when compared with the control period, whereas they were not significantly different in the period of pomegranate juice [C max and AUCinf 1.20 (0.89-1.62) and 1.29 (0.85-1.94)]. The mean C max and AUCinf of simvastatin acid were increased significantly after intake of grapefruit juice, but not pomegranate juice. These results suggest that pomegranate juice affects little on the disposition of simvastatin in humans. Pomegranate juice does not seem to have a clinically relevant inhibitory potential on CYP3A4 activity.

Effects of clopidogrel and clarithromycin on the disposition of sibutramine and its active metabolites M1 and M2 in relation to CYP2B6*6 polymorphism.

Plasma concentrations of sibutramine and its two active metabolites after single oral dose of sibutramine were determined in Korean healthy male subjects with different CYP2B6 genotypes (CYP2B6*1/*1, *1/*6 and *6/*6), either alone or after four-day pretreatment with clopidogrel or clarithromycin. The pretreatment with clopidogrel and clarithromycin raised the mean area under the concentration-time curve (AUC) of sibutramine by 163% and 255%, respectively. Co-administration of clarithromycin, combined with CYP2B6*6/*6 genotype, led to highest concentration of sibutramine. The molar sum AUC (M1 + M2) was raised by 35% in the clopidogrel phase but not significantly affected by clarithromycin or CYP2B6 genotype. The CYP2B6*6/*6 subjects in the clopidogrel phase showed the highest molar AUC (M1 + M2) among three genotype groups throughout the three phases. The exposure of sibutramine and its metabolites seemed to be associated with the CYP2B6 genotype. The treatment of clopidogrel significantly altered the disposition of active metabolites as well as sibutramine, but clarithromycin only affects the disposition of sibutramine. These results suggest that the perturbation of CYP2B6 activity may contribute to the inter-individual variation of sibutramine drug responses although the clinical relevance is remained to be established.

Effects of woohwangcheongsimwon suspension on the pharmacokinetics of bupropion and its active metabolite, 4-hydroxybupropion, in healthy subjects.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Woohwangcheongsimwon suspension has traditionally been used for the treatment and prevention of stroke, hypertension, palpitations, convulsions and unconsciousness in various Asian countries. Woohwangcheongsimwon suspensions showed an inhibitory effect on CYP2B6 activity in vitro. Two terpenoids, borneol and isoborneol, are major constituents of woohwangcheongsimwon suspension, and show a competitive inhibition of CYP2B6 with K(i) values of 9.5 and 5.9 microM, respectively. Bupropion undergoes metabolic transformation to the active metabolite, 4-hydroxybupropion, primarily via CYP2B6 both in vivo and in vitro. It is often used as a CYP2B6 substrate for clinical drug-drug interaction studies. Drug interactions may occur between woohwangcheongsimwon suspension and bupropion. WHAT THIS STUDY ADDS: Co-administration with woohwangcheongsimwon suspension did not alter the pharmacokinetics of bupropion or its metabolite, 4-hydroxybupropion. Dosage adjustment of bupropion is unnecessary in patients concomitantly administered the highest recommended daily dose of woohwangcheongsimwon suspension. AIMS: To examine the effects of woohwangcheongsimwon suspension on the pharmacokinetics of bupropion and its active metabolite, 4-hydroxybupropion, formed via CYP2B6 in vivo. METHODS: A two-way crossover clinical trial with a 2 week washout period was conducted in 14 healthy volunteers. In phases I and II, subjects received 150 mg bupropion with or without woohwangcheongsimwon suspension four times (at -0.17, 3.5, 23.5 and 47.5 h, with the time of bupropion administration taken as 0 h) in a randomized balanced crossover order. Bupropion and 4-hydroxybupropion plasma concentrations were measured for up to 72 h by LC-MS/MS. Urine was collected up to 24 h to calculate the renal clearance. In addition, the CYP2B6*6 genotype was also analyzed. RESULTS: The geometric mean ratios and 90% confidence interval of bupropion with woohwangcheongsimwon suspension relative to bupropion alone were 0.976 (0.917, 1.04) for AUC(0,infinity) and 0.948 (0.830,1.08) for C(max), respectively. The corresponding values for 4-hydroxybupropion were 0.856 (0.802, 0.912) and 0.845 (0.782, 0.914), respectively. The t(max) values of bupropion and 4-hydroxybupropion were not significantly different between the two groups (P > 0.05). The pharmacokinetic parameters of bupropion and 4-hydroxybupropion were unaffected by woohwangcheongsimwon suspension. CONCLUSIONS: These results indicate that woohwangcheongsimwon suspension has a negligible effect on the disposition of a single dose of bupropion in vivo. As a result, temporary co-administration with woohwangcheongsimwon suspension does not seem to require a dosage adjustment of bupropion.

HPLC determination of irbesartan in human plasma: its application to pharmacokinetic studies.

A simple and rapid HPLC method using fluorescence detection was developed for determination of irbesartan in human plasma. Sample preparation was accomplished through a simple deproteinization procedure with 0.4 mL of acetonitrile containing 800 ng/mL of losartan (internal standard), and to a 0.1 mL plasma sample. Chromatographic separation was performed on a Zorbax Xclipse XDB C18 column (150 x 4.6 mm, i.d., 5 microm) at 40 degrees C. An isocratic mobile phase, acetonitrile:0.1% formic acid (37:63, v/v), was run at a flow-rate of 1.0 mL/min, and the column eluent was monitored using a fluorescence detector set at excitation and emission wavelengths of 250 and 370 nm, respectively. The retention times of irbesartan and losartan were 4.4 and 5.9 min, respectively. This assay was linear over a concentration range of 10-5000 ng/mL with a lower limit of quantification of 10 ng/mL. The coefficient of variation for this assay precision was less than 8.48%, and the accuracy exceeded 94.4%. The mean relative recoveries of irbesartan and losartan were 98.4 and 99.1%, respectively. This method was successfully applied for pharmacokinetic study after oral administration of irbesartan (300 mg) to 23 Korean healthy male volunteers.

The differential effects of emotional or physical stress on pain behaviors or on c-Fos immunoreactivity in paraventricular nucleus or arcuate nucleus.

Although many studies which explore on the interaction between stress and antinociception have been conducted, most of them do not divide stress into emotional stress (ES) and physical stress (PS). In the present study, we investigated the differential effects of ES or PS on pain behaviors or on c-Fos immunoreactivity (IR) in the paraventricular nucleus (PVN) or arcuate nucleus (ArcN) using electrical footshock-witness model. In addition, alteration of pain behaviors or c-Fos IR following stress repetition was examined. The electrical foot shock was applied to PS animal group in one chamber, whereas the witness animal group in another chamber without any electrical foot shock was regarded as an ES. In each group, either single (10 stimuli /10 min/1 day) or repeated stress for 5 consecutive days was applied. Our results suggest that ES and PS appear to play differential roles in the regulation of nociception produced by various types of pain stimuli (formalin, substance P, glutamate or pro-inflammatory cytokines) and on c-Fos IR in the PVN or ArcN. Moreover, such antinociceptive effect or c-Fos IR appears to be modified following stress repetition.

The intracerebroventricular kainic acid-induced damage affects animal nociceptive behavior.

In the present study, we examined nociceptive behaviors on various pain models after the pretreatment of kainic acid intracerebroventricularly. We found that intracerebroventricular administration of kainic acid shows significant neuronal damage on the hippocampal CA3 region in the brain slices stained with cresyl violet. Compared to the control group, intracerebroventricular pretreatment of kainic acid significantly attenuated nocifensive behaviors induced by intraplantar formalin (only in the 2nd phase), intrathecal glutamate, TNF-alpha or IL-1beta. However, nocifensive behaviors induced by intraperitoneal acetic acid (writhing test), intrathecal substance P or IFN-gamma were not affected by the pretreatment of kainic acid. These results suggest that (1) KA-induced alterations of nocifensive behaviors are related to the neuronal death of the hippocampal formation, especially CA3 pyramidal neurons and (2) nocifensive behaviors induced by formalin, acetic acid, SP, glutamate, and pro-inflammatory cytokines were modulated in a different manner.

Changes in pain behavior induced by formalin, substance P, glutamate and pro-inflammatory cytokines in immobilization-induced stress mouse model.

In the present study, we examined the change of pain behaviors induced by formalin injected subcutaneously (s.c.) into the hind paw, or substance P (SP), glutamate, and pro-inflammatory cytokines (TNF-alpha, IL-1beta, and IFN-gamma) injected intrathecally (i.t.) in the mouse immobilization stress model. The mouse was restrained either once for 1h or five times for 5 days (once/day). In the formalin test, a single immobilization stress attenuated pain behaviors (licking, biting or scratching) in the second phase, while it had no effect on the pain behaviors revealed during the first phase. In addition, repeated immobilization stress attenuated pain behaviors revealed during the second phase but not in the first phase. A single as well as repeated immobilization stress decreased pain behaviors induced by substance P i.t. injection, but there were no significant changes in the glutamate test. In the pro-inflammatory cytokine pain model, a single immobilization stress decreased the pain behaviors induced by TNF-alpha, IL-1beta administered i.t. but not by IFN-gamma administered i.t. Moreover, a mouse applied with repeated immobilization stress did not show any changes in pain behaviors elicited by pro-inflammatory cytokines (TNF-alpha, IL-1beta and IFN-gamma) compared to the control group. These results suggest that a single and repeated immobilization stress differentially affects such nociceptive processing induced by formalin, SP, glutamate and pro-inflammatory cytokines in different manners.

The effects of phorbol 12-myristate 13-acetate, cholera toxin, prostaglandin E2 and norepinephrine on inducible nitric oxide synthase activation induced by lipopolysaccharide in C6 cells.

Nitric oxide (NO) plays a significant role in the pathophysiology of the central nervous system including inflammatory, ischemic and traumatic injuries. We demonstrated the possible involvement of protein kinase C (PKC) as well as protein kinase A (PKA) in the regulation of NO synthesis induced by lipopolysaccharide (LPS) treatment. In this study, the role of phorbol 12-myristate 13-acetate (PMA), cholera toxin (CTX), pertussis toxin (PTX), prostaglandin E(2) (PGE(2)) and norepinephrine (NE) in the regulation of NO synthesis was examined in C6 glioma cells. Stimulation with LPS (1 microg/ml) evoked increases in NO production in C6 glioma cells. LPS-induced NO production was enhanced by pretreatment with PMA, CTX and PGE(2). PTX pretreatment had no effect on NO production induced by LPS. In addition, NE inhibited NO production elicited by LPS treatment. These results suggest that NO production induced by LPS in C6 glioma cells is regulated by several kinds of pathways in which CTX-specific G protein, PKC, prostanoid EP(4) receptor and adrenergic receptor may play important roles.

Involvement of phosphorylated Ca2+/calmodulin-dependent protein kinase II and phosphorylated extracellular signal-regulated protein in the mouse formalin pain model.

In the present study, we investigated the role of phosphorylated calcium/calmodulin-dependent protein kinase II (pCaMK-II) and phosphorylated extracellular signal-regulated protein kinase (pERK) in nociceptive processing at the spinal and supraspinal levels in the formalin subcutaneous induced mouse pain model. In the immunoblot assay, subcutaneous (s.c.) injection with formalin increased the pERK and pCaMK-IIalpha level in the spinal cord, and an immunohistochemical study showed that the increase of pERK and pCaMK-IIalpha immunoreactivity mainly occurred in the laminae I and II areas of the spinal dorsal horn. At the supraspinal level, although pERK was not changed in the hippocampus induced by formalin s.c. injection, pCaMK-IIalpha was increased in the hippocampus and hypothalamus by s.c. formalin injection, and an increase of pCaMK-IIalpha immunoreactivity mainly occurred in the pyramidal cells and the stratum lucidum/radiatum layer of the CA3 region of hippocampus and paraventricular nucleus of the hypothalamus. Moreover, pERK immunoreactivity in the hypothalamic paraventricular nucleus was also increased. The second phase of nociceptive behavior induced by formalin administered either i.t. or intracerebroventricularly (i.c.v.) was attenuated by PD98059 (ERK inhibitor) as well as KN-93(a CaMK-II inhibitor). On the other hand, the first phase of nociceptive behavior induced by formalin s.c. injection was not affected by i.t. KN-93. Our results suggest that pERK and pCaMK-II located at both the spinal cord and supraspinal levels are an important regulator during the nociceptive processes induced by formalin administered s.c. respectively.

Differential modulatory effects of cholera toxin and pertussis toxin on pain behavior induced by TNF-alpha, interleukin-1beta and interferon-gamma injected intrathecally.

The present study was designed to characterize the possible roles of spinally located cholera toxin (CTX)- and pertussis toxin (PTX)-sensitive G-proteins in pro-inflammatory cytokine induced pain behaviors. Intrathecal injection of tumor necrosis factor-alpha (TNF-alpha; 100 pg), interleukin-1beta (IL-1beta; 100 pg) and interferon-gamma (INF-gamma; 100 pg) showed pain behavior. Intrathecal pretreatment with CTX (0.05, 0.1 and 0.5 mg) attenuated pain behavior induced by TNF-alpha and INF-gamma administered intrathecally. But intrathecal pretreatment with CTX (0.05, 0.1 and 0.5 microg) did not attenuate pain behavior induced by IL-1beta. On the other hand, intrathecal pretreatment with PTX further increased the pain behavior induced by TNF-alpha and IL-1beta administered intrathecally, especially at the dose of 0.5 microg. But intrathecal pretreatment with PTX did not affect pain behavior induced by INF-gamma. Our results suggest that, at the spinal cord level, CTX- and PTX-sensitive G-proteins appear to play important roles in modulating pain behavior induced by pro-inflammatory cytokines administered spinally. Furthermore, TNF-alpha, IL-1beta and INF-gamma administered spinally appear to produce pain behavior by different mechanisms.

Involvement of phosphorylated extracellular signal-regulated kinase in the mouse substance P pain model.

In the present study, we investigated the role of pERK in nociceptive processing at the spinal and supraspinal levels in the substance P (SP)-induced mouse pain model. In the immunoblot assay, intrathecal (it) injection with SP increased pERK level at the spinal cord and an immunohistochemical study showed that increase of pERK immunoreactivity mainly occurred in the lamina I and II areas of the spinal dorsal horn. At the supraspinal level, pERK was increased in hippocampus and hypothalamus by i.t. SP injection, and an increase of pERK immunoreactivity mainly occurred in the dentate gyrus and CA3 region of hippocampus and paraventricular nucleus on hypothalamus. The nociceptive behavior induced by Sub P administered either i.t. or intracerebroventricularly (i.c.v.) was attenuated by PD98059 (a MEK 1/2 inhibitor) in a dose-dependent manner. Our results suggest that pERK located at both spinal cord and supraspinal levels plays as an important regulator during the nociceptive process activated by SP administered it.

Kainic acid (KA)-induced Ca2+/calmodulin-dependent protein kinase II (CaMK II) expression in the neurons, astrocytes and microglia of the mouse hippocampal CA3 region, and the phosphorylated CaMK II only in the hippocampal neurons.

In the present study, we investigated the role of Ca2+/calmodulin-dependent protein kinase II (CaMK II) and which types of neuronal cells contain CaMK II and phosphorylated CaMK II (p-CaMK II) in the CA3 hippocampal region of mice using confocal immunofluorescence study. KA increased the CaMK II, p-CaMK II, glial fibrillary acidic protein (GFAP) and complement receptor type 3 (OX-42) immunoreactivities (IR) at 30 min after KA treatment in mouse hippocampal area. In studies, nevertheless KA-induced CaMK II is expressed in neurons or astrocytes or microglia, p-CaMK II is expressed only in neurons. Thus, our results suggest that the activated CaMK II in early time may be performed important roles only in neurons but not in the astrocytes and microglia.

Increase of phosphorylation of calcium/calmodulin-dependent protein kinase-II in several brain regions by substance P administered intrathecally in mice.

In the present study, we investigated the role of phosphorylated calcium/calmodulin-dependent protein kinase-II (pCaMK-II) in nociceptive processing at the spinal and supraspinal levels in the substance P (SP)-induced mouse pain model. In the immunoblot assay, intrathecal (i.t.) injection with SP increased the pCaMK-II level in the spinal cord, and an immunohistochemical study showed that the increase of pCaMK-II immunoreactivity mainly occurred in the laminae I and II areas of the spinal dorsal horn. At the supraspinal level, pCaMK-II was increased in the hippocampus and hypothalamus by i.t. SP injection, and an increase of pCaMK-II immunoreactivity mainly occurred in the pyramidal cells and the stratum lucidum/radiatum layer of the CA3 region of hippocampus and paraventricular nucleus of the hypothalamus. Moreover, pCaMK-II immunoreactivity in the locus coelureus of the brain stem was also increased. The nociceptive behavior induced by SP administered either i.t. or intracerebroventricularly (i.c.v.) was attenuated by KN-93 (a CaMK-II inhibitor). Our results suggest that pCaMK-II located at both spinal cord and supraspinal levels is an important regulator during the nociceptive processes induced by SP administered i.t.

Antinociceptive effect of nicotine in various pain models in the mouse.

The antinociceptive effect of nicotine administered intracereboventricularly (i.c.v.) or intrathecally (i.t) in several pain models was examined in the present study. We found that i.t. treatment with nicotine (from 5 to 20 g) dose-dependently blocked pain behavior revealed during the second phase, but not during the first phase in the formalin test. In addition, i.c.v. treatment with nicotine (from 0.1 to 10 microg) dose-dependently attenuated pain behavior revealed during both the first and second phases. In addition to the formalin test, nicotine administered i.c.v. or i.t. attenuated acetic acid-induced writhing response. Furthermore, i.c.v. or i.t. administration of nicotine did not cause licking, scratching and biting responses induced by substance P, glutamate, TNF-alpha (100 pg), IL-1beta (100 pg) and INF-gamma (100 pg) injectied i.t. The antinociception induced by supraspinally-administered nicotine appears to be more effective than that resulting from spinally administered nicotine. Our results suggest that nicotine administration induces antinociception by acting on the central nervous system and has differing antinociceptive profiles according to the various pain models.

Formalin pretreatment attenuates tail-flick inhibition induced by beta-endorphin administered intracerebroventricularly or intrathecally in mice.

We examined the effect of the subcutaneous (s.c.) pretreatment of formalin into both hind paws of mice on the antinociception induced by the intracerebroventricularly (i.c.v.) or intrathecally (i.t.) administration of beta-endorphin using the tail-flick test. Pretreatment with formalin (5%) for 5 h had no affect on the i.c.v. administered beta-endorphin-induced tail-flick response. However, pretreatment with formalin for 40 h attenuated the tail-flick inhibition induced by i.c.v. administered beta-endorphin. This antinociceptive tolerance to i.c.v. beta-endorphin continued up to 1 week, but to a lesser extent. Pretreatment with formalin for 5 and 40 h significantly reduced the i.t. beta-endorphin-induced inhibition of the tail-flick response, which continued up to 1 week. The s.c. formalin treatment increased the hypothalamic pro-opiomelanocortin (POMC) mRNA level at 2 h, but this returned to the basal level after 40 h. Our results suggest that the increase in the POMC mRNA level in the hypothalamus appears to be involved in the supraspinal or spinal beta-endorphin-induced antinociceptive tolerance in formalin-induced inflammatory pain.

Effect of aspirin and acetaminophen on proinflammatory cytokine-induced pain behavior in mice.

Aspirin (ASA) is a widely used oral analgesic which acts as an inhibitor of cyclooxygenase. Acetaminophen (ACET) is also an effective analgesic and may selectively inhibit brain prostaglandin synthetase. Various proinflammatory cytokines injected into the central nervous system show pain behavior. In the present study, the effects of orally administered ASA and ACET on pain behaviors induced by various proinflammatory cytokines were examined. At a dose of 100 mg/kg, ASA or ACET did not affect the pain behavior induced by TNF-alpha (100 pg), IL-1beta (100 pg) or IFN-gamma (100 pg) administered intrathecally. However, at doses of 200 and 300 mg/kg, ASA or ACET significantly and dose-dependently attenuated pain behavior induced by TNF-alpha, IL-1beta or IFN-gamma administered intrathecally. Our results suggest that orally administered ASA and ACET produce antinociception by inhibiting the nociceptive action of TNF-alpha, IL-1beta or IFN-gamma administered intrathecally.

Role of gamma-aminobutyricacidB(GABA(B)) receptors in the regulation of kainic acid-induced cell death in mouse hippocampus.

Kainic acid (KA) is well-known as an excitatory, neurotoxic substance. In mice, KA administered intracerebroventricularly (i.c.v.) lead to morphological damage of hippocampus expecially concentrated on the CA3 pyramidal neurons. In the present study, the possible role of gamma-aminobutyric acid B (GABA(B)) receptors in hippocampal cell death induced by KA (0.1 microg) administered i.c.v. was examined. 5-Aminovaleric acid (5-AV; GABA(B) receptors antagonist, 20 mug) reduced KA-induced CA3 pyramidal cell death. KA increased the phosphorylated extracellular signal-regulated kinase (p-ERK) and Ca(2+)/calmodulin-dependent protein kinase II (p-CaMK II) immunoreactivities (IRs) 30 min after KA treatment, and c-Fos, c-Jun IR 2 h, and glial fibrillary acidic protein (GFAP), complement receptor type 3 (OX-42) IR 1 day in hippocampal area in KA-injected mice. 5-AV attenuated KA-induced p-CaMK II, GFAP and OX-42 IR in the hippocampal CA3 region. These results suggest that p-CaMK II may play as an important regulator on hippocampal cell death induced by KA administered i.c.v. in mice. Activated astrocytes, which was presented by GFAP IR, and activated microglia, which was presented by the OX-42 IR, may be a good indicator for measuring the cell death in hippocampal regions by KA excitotoxicity. Furthermore, it showed that GABA(B) receptors appear to be involved in hippocampal CA3 pyramidal cell death induced by KA administered i.c.v. in mice.

Role of nicotinic acetylcholine receptors in the regulation of kainic acid-induced hippocampal cell death in mice.

Kainic acid (KA) is a well-known excitatory, neurotoxic substance. In mice, morphological damage of hippocampus induced by KA administered intracerebroventricularly (i.c.v.) was markedly concentrated on the CA3 pyramidal neurons. In the present study, the possible role of nicotinic acetylcholine receptors (nAchRs) in hippocampal cell death induced by KA (0.1 microg) administered i.c.v. was examined. Methyllycaconitine (MC; nAchRs antagonist, 20 microg) attenuated KA-induced CA3 pyramidal cell death. KA increased immunoreactivities (IRs) of phorylated extracellular signal-regulated kinase (p-ERK; at 30 min), p-CaMK II (at 30 min), c-Fos (at 2 h), c-Jun (at 2 h), glial fibrillary acidic protein (GFAP at 1 day), and the complement receptor type 3 (OX-42; at 1 day) in hippocampal area. MC attenuated selectively KA-induced p-CaMK II, GFAP and OX-42 IR in the hippocampal CA3 region. Our results suggest that p-CaMK II may play as an important regulator responsible for the hippocampal cell death induced by KA administered i.c.v. in mice. Reactive astrocytes, which was meant by GFAP IR, and activated microglia, which was meant by OX-42 IR, may be a good indicator for measuring the cell death in hippocampal regions by KA-induced excitotoxicity. Furthermore, it is implicated that niconitic receptors appear to be involved in hippocampal CA3 pyramidal cell death induced by KA administered i.c.v. in mice.