Intra-hippocampal inhibition of protein kinase AII attenuates morphine-induced conditioned place preference

Morphine and other drugs of abuse modulate protein kinase A (PKA) signaling within the mesolimbic reward pathway. Using a balanced conditioned place preference (CPP) paradigm, we studied the possible involvement of protein kinase AII (PKA II) on the acquisition, expression and consolidation of morphine place conditioning in male Wistar rats. Subcutaneous administration of various doses of morphine sulfate (1-9 mg/kg) induced CPP in a dose-dependent manner. H-89, a selective PKA II inhibitor, was administered into CA1 region of the hippocampus at 1, 2.5 and 5 microM/rat. Using a 3-day schedule of conditioning, it was found that the H-89 did not produce a significant place preference or place aversion. H-89 (1, 2.5 and 5 microM/rat) significantly reduced the time spent by rats in the morphine compartment when given immediately after each conditioning session (consolidation), whereas it had no effect when administered before morphine during the conditioning phase (acquisition) or before testing for place preference in the absence of morphine (expression). It is concluded that the PKA II may play an active role in the consolidation of reward-related memory of morphine in CA1 region of the hippocampus.

Inhibition of the cyclooxygenase pathway attenuates morphine-induced conditioned place preference in mice

Prostanoids are shown to be important lipid mediators, not only in periphery but also in the brain, where they appear to modulate synaptic transmission. Recent studies have demonstrated that cyclooxygenase (COX) pathway might modulate the neurotransmission of gamma-aminobutyric acid and dopamine in the central nervous system. In this study, we have evaluated the effects of indomethacin (a non-selective COX inhibitor) and celecoxib (a selective COX-2 inhibitor) on the acquisition of morphine-induced conditioned place preference (CPP) in male Swiss mice. Our data shows that morphine (2.5-7.5 mg/kg) induces place preference conditioning in a dose-dependent manner. Celecoxib (0.01-5 mg/kg) and indomethacin (1 mg/kg) fail to produce a significant CPP or conditioned place aversion (CPA); however, higher doses of celecoxib (10 mg/kg) and indomethacin (5 mg/kg) induce CPA. Co-administration of celecoxib (0.5-5 mg/kg) or indomethacin (1-5 mg/kg) with morphine during the conditioning phase, blocked the acquisition of morphine CPP. These results indicate that the reward properties of morphine can be modulated by inhibiting COX activity in mice.

Restoration of morphine-induced alterations in rat submandibular gland function by N-methyl-D-aspartate agonist

The effects of morphine, 1-aminocyclobutane-cis-1,3-dicarboxylic (ACBD; NMDA agonist) and 3-((R)2-carboxypiperazin-4-yl)-propyl-l-phosphoric acid (CPP; NMDA antagonist) and their concurrent therapy on rat submandibular secretory function were studied. Pure submandibular saliva was collected intraorally by micro polyethylene cannula from anaesthetized rats using pilocarpine as secretagogue. Intraperitoneal injection of morphine (6 mg/kg) induced significant inhibition of salivary flow rate, total protein, calcium, and TGF-beta1 concentrations. Administration of ACBD (10 mg/kg) and CPP (10 mg/kg) alone did not influence secretion of submandibular glands. In combination therapy, coadministration of CPP with morphine did not influence morphine-induced changes in salivary function while ABCD could restore all morphine-induced changes. In combination treatment, ACBD prevented morphine-induced reduction of flow rate, total protein, calcium, and TGF-beta1 and reached control levels. It is concluded that morphine-induced alterations in submandibular gland function are mediated through NMDA receptors.

Effects of aqueous, methanolic and chloroform extracts of rhizome and aerial parts of Valeriana officinalis L. on naloxone-induced jumping in morphine-dependent mice

In the present study, the effects of rhizomes and aerial parts extracts of Valeriana officinalis L. on morphine dependence in mice have been investigated. Animals were treated subcutaneously with morphine (50, 50 and 75 mg/kg) three times daily (10 am, 1 pm and 4 pm) for 3 days, and a last dose of morphine (50 mg/kg) was administered on the fourth day. Withdrawal syndrome (jumping) was precipitated by naloxone (5 mg/kg) which was administered intraperitoneally 2 hours after the last dose of morphine. To study the effects of the aqueous, methanolic and chloroform extracts of both aerial parts and rhizome of the V. officinalis L. on naloxone-induced jumping in morphine-dependent animals, 10 injections of morphine (three administrations each day) for dependence and a dose of 5 mg/kg of naloxone for withdrawal induction were employed. Intraperitoneal injection of different doses (1, 5, 25 and 50 mg/kg) of aqueous, methanolic and chloroform extracts of the rhizome of V. officinalis L. 60 minutes before naloxone injection decreased the jumping response dose-dependently. Pre-treatment of animals with different doses (1, 5, 25, 50 and 100 mg/kg) of aqueous and methanolic extracts of aerial parts of V. officinalis L. 60 minutes before naloxone injection caused a significant decrease on naloxone-induced jumping. The chloroform extract of the aerial parts of V. officinalis L. did not show any significant changes on jumping response in morphine-dependent animals. It is concluded that the extracts of V. officinalis L. could affect morphine withdrawal syndrome via possible interactions with inhibitory neurotransmitters in nervous system.

A time course analysis of cyclooxygenase-2 suggests a role in spatial memory retrieval in rats

We previously showed a role for COX-2 in spatial memory retention. In that study we investigated the effects of post-training intrahippocampal infusion of celecoxib as a COX-2-specific inhibitor on spatial memory retention. Those infusions impaired spatial memory retention in the Morris water maze. In the present study a time course analysis of role of COX-2 in spatial memory was conducted. Here stereotaxic surgery was employed for the bilateral implantation of guide cannulas into the CA1 region of the hippocampus. Training trials were started after recovery of the animals. Immediately after last trial of training on third day, the celecoxib (0.1M) was infused bilaterally and testing trials, were performed 1, 2, 3, and 7 days after celecoxib infusions. Significant alterations were observed in escape latency and traveled distance 2 and 3 days after celecoxib infusions. The maximum impairment was obtained 72 h after the infusions. The data suggests that the effect of celecoxib is transient and that its effect on performance is likely caused by a problem in memory retrieval. Quantification analyses of the immunostaining of COX-2-containing neurons in the dorsal hippocampus show that celecoxib infusions significantly reduced (P<0.05) COX-2 immunoreactivity for the animals that were tested 3 days after the drug infusion. Results from the behavioral study along with the findings from immunohistochemical analyses suggest that COX-2 has significant role in spatial memory retrieval. Moreover, the memory deficits induced by the infusions continuously persists for 3 days.

Rural domestic water consumption behavior: A case study in Ramjerd area, Fars province, I.R. Iran

Identifying the factors that affect domestic water demand and consumption is very important in management of available regional water resources. In this study, relationships between water consumption and rural household activities are determined by comparing a snapshot of water consumption with rural household behavior of low, medium and high water consumers. In addition, the factors affecting water consumption in rural households are also determined. The data for this study were collected from a survey of 653 rural households in 33 villages of Ramjerd area, Fars Province, in southern Iran, using a simple random sampling technique. The daily water consumption data for a 5-year period (1999-2004) were used. Results of the study revealed that the daily average water consumption for the area was found to be 121.7 l per person per capita per day (Lpcd) (SD = 59.2). Water consumption was also found to be significantly correlated with explanatory variables such as "household size" and "age of household's head". Finally, the results of discriminant function analysis showed that in rural households, garden size, greenhouse size, and garden watering times per month with tap treated water are associated with water consumption.

Post-training intrahippocampal infusion of nicotine prevents spatial memory retention deficits induced by the cyclo-oxygenase-2-specific inhibitor celecoxib in rats

Recently, we demonstrated that intrahippocampal infusion of the cyclo-oxygenase (COX)-2-specific inhibitor celecoxib impaired spatial memory retention in the Morris water maze. In the present work, we investigated the effects of nicotine, infused in the rat dorsal hippocampus several minutes after infusion of celecoxib, on memory retention in the Morris water maze. Rats were trained for 3 days; each day included two blocks, and each block contained four trials. Test trials were conducted 48 h after surgery. As expected, bilateral intrahippocampal infusion of celecoxib (19 microg/side; 0.1 m) increased escape latency and travel distance in rats, indicating significant impairment of spatial memory retention. We also examined the effects of bilateral infusion of nicotine (0.5, 1.0 and 2.0 microg/side) on memory retention. Infusion of 1 microg nicotine significantly decreased escape latency and travel distance but not swimming speed, compared with controls, suggesting memory retention enhancement by nicotine at this concentration. In separate experiments, bilateral infusion of nicotine, infused 5 min after 0.1 m (19 microg/side) celecoxib infusion, was associated with escape latency, travel distance and swimming speed profiles very similar to those in control animals. Brain tissue sections from several of these animals were subjected to immunohistochemical staining analysis with anti-COX-2 antibodies. Quantification analysis by optical density measurements showed that the celecoxib infusion reduced the immunoreactivity of COX-2-containing neurons in the CA1 area of the hippocampus compared with controls, although this reduction was not significant. However, infusion of a combination of celecoxib and nicotine significantly increased this immunoreactivity compared with levels in control and celecoxib-infused groups. These results suggest that nicotine prevented or reversed the adverse effects of celecoxib on spatial memory retention and protected or restored the immunostaining pattern of COX-2 neurons in the rat dorsal hippocampus.

Resonance Raman detection of carotenoid antioxidants in living human tissue

Increasing evidence points to the beneficial effects of carotenoid antioxidants in the human body. Several studies, for example, support the protective role of lutein and zeaxanthin in the prevention of age-related eye diseases. If present in high concentrations in the macular region of the retina, lutein and zeaxanthin provide pigmentation in this most light sensitive retinal spot, and as a result of light filtering and/or antioxidant action, delay the onset of macular degeneration with increasing age. Other carotenoids, such as lycopene and beta-carotene, play an important role as well in the protection of skin from UV and short-wavelength visible radiation. Lutein and lycopene may also have protective function for cardiovascular health, and lycopene may play a role in the prevention of prostate cancer. Motivated by the growing importance of carotenoids in health and disease, and recognizing the lack of any accepted noninvasive technology for the detection of carotenoids in living human tissue, we explore resonance Raman spectroscopy as a novel approach for noninvasive, laser optical carotenoid detection. We review the main results achieved recently with the Raman detection approach. Initially we applied the method to the detection of macular carotenoid pigments, and more recently to the detection of carotenoids in human skin and mucosal tissues. Using skin carotenoid Raman instruments, we measure the carotenoid response from the stratum corneum layer of the palm of the hand for a population of 1375 subjects and develop a portable skin Raman scanner for field studies. These experiments reveal that carotenoids are a good indicator of antioxidant status. They show that people with high oxidative stress, like smokers, and subjects with high sunlight exposure, in general, have reduced skin carotenoid levels, independent of their dietary carotenoid consumption. We find the Raman technique to be precise, specific, sensitive, and well suitable for clinical as well as field studies. The noninvasive laser technique may become a useful method for the correlation between tissue carotenoid levels and risk for malignancies or other degenerative diseases associated with oxidative stress.

Post-training intrahippocampal infusion of the COX-2 inhibitor celecoxib impaired spatial memory retention in rats

In this study, we investigated the effects of intrahippocampal infusion of indomethacin as a non-selective cyclooxygenase inhibitor and celecoxib as a selective cyclooxygenase-2 inhibitor on spatial memory in the Morris water maze. Rats were trained for 3 days; each day included two blocks, and each block contained 4 trials. Tests were performed 48 h after surgery. Bilateral intrahippocampal infusion of indomethacin (0.01, 0.1, or 1 M) did not show any significant effect on spatial memory retention at these concentrations in rats. We also examined effects of infusion of celecoxib (0.02, 0.06, or 0.1 M) on memory retention. Bilateral infusion of 0.1 M celecoxib significantly altered escape latency and traveled distance in rats. These results strongly suggest that cyclooxygenase-2 is involved in spatial memory retention.

Evaluation of patient-related factors associated with causality, preventability, predictability and severity of hepatotoxicity during antituberculosis [correction of antituberclosis] treatment

For evaluation the extent of antituberculosis drug-induced hepatotoxicity and also to determine the patient-related factors associated with causality, preventability, predictability and severity of hepatotoxicity induced by antituberculosis medications, a prospective study was conducted on 112 patients in a tertiary care university teaching hospital for three years. Causality, preventability, predictability and severity of hepatotoxicity were determined based on the available standard algorithms. Of 112 patients, 31 (27.7%) demonstrated hepatotoxicity. Two patients died from complications of liver-related illness. The mean duration of treatment before the onset of hepatotoxicity was 16.7+/-3.2 days. Malnutrition was present in 17 of 112 patients. Most of hepatotoxicity (25/31 or 80.6%) occurred within the first month of treatment. Reintroduction of antituberculosis drugs was possible in 29 of 31 patients. Univariate and multivariate analysis did not show significant relationships between the rate of hepatotoxicity with age, sex, nutrition and nationality. Our results showed that hepatotoxicity induced by antituberculosis drugs is a nonpreventable and unpredictable reaction. The causality of this reaction is classified as category A based on European grading of causality. This study noted that the frequency of hepatotoxicity induced by antituberculosis drugs in Iranian patients is higher than other studied populations.

Anti-infectives-induced adverse drug reactions in hospitalized patients

OBJECTIVES

To assess the rate and seriousness of adverse drug reactions (ADRs) attributable to anti-infective agents in hospitalized patients; to estimate the likelihood of experiencing anti-infectives-induced ADRs at different length of drug usage in the hospital; to compare different classes of anti-infectives in inducing ADRs; to determine the impact of age and sex on anti-infectives-induced ADRs.

DESIGN

Prospective cohort study.

PARTICIPANTS

Patients admitted to the infectious diseases department at a university teaching hospital, on Sunday to Wednesday, over a 9 months period, who received at least one anti-infective agent were eligible to enter the study.

MAIN OUTCOME MEASURES

Any suspected noxious and untoward medical events, including laboratory tests abnormalities following anti-infective therapy.

METHODS

All patients admitted have received at least one anti-infective drug. Anti-infective agents induced ADRs were detected by interviewing patients and daily chart review. The seriousness, causality, and type of reactions were classified based on World Health Organization (WHO) definitions. Chi-square analysis was performed to assess the influence of sex and age on occurring ADRs. Both Kaplan-Meier and life table method were used to estimate the time to occur the ADR in anti-infective users. To compare the estimated risk of ADRs induced by different classes of anti-infectives, odds ratios were estimated. In all classes of anti-infectives, the odds ratio of each class was estimated with regard to anti-tuberculosis agents, which had the highest prevalence of ADRs.

RESULTS

During the study period, 460 patients were entered the study. During the same period, 38 ADRs were recognized of which 20 (42%) were serious. The most recognized ADRs were suspected to be induced by anti-tuberculosis agents (29.8%). However in comparing with anti-tuberculosis agents, anti-fungal agents were associated with the highest ADR rate (odds ratio [OR], 4.21; 95% confidence interval [CI], 1.41-1.256) whereas cephalosporines were associated with the lowest rate, (OR, 0.1; 95%CI, 0.04-0.26). The survival analysis shows that the likelihood of experiencing an ADR was increased at first 14 days of drug therapy. Also Chi-square analysis shows that greater risk of anti-infectives-induced ADRs was observed in women.

CONCLUSION

The rate of ADRs induced by anti-infective agents in this study was 8.2%. This is higher than a standard (5%) which has been reported in other studies. This study also shows that some of the classes of anti-infective agents like anti-fungals need more attention.

Phytochemical investigation and anti-inflammatory activity of aerial parts of Stachys byzanthina C. Koch

From the aerial parts of Stachys byzanthina C. Koch., an acyclic diterpene ester, phytyl nonadecanoate, was isolated for the first time. In addition, two normal alkanes, one fatty acid and two sterols were also identified. Stuctures were established by conventional methods of analysis and confirmed by 1H, 13C NMR and mass spectral analysis. Anti-inflammatory effects of acetone and methanolic extracts of aerial parts of Stachys byzanthina C. Koch. were investigated in this study. For assessment of anti-inflammatory properties, two well-characterized inflammatory models, formalin test and carrageenan-induced paw edema were used. Intraperitoneal injections of either acetone or methanolic extract of Stachys byzanthina C. Koch. (50, 100 and 200 mg/kg), 30 min before formalin injection, had no effects against the first phase of the formalin-induced pain, but all three doses caused a significant blockade on the second phase (p < 0.01). The recording of the early phase started immediately after formalin injection and lasted for 10 min (0-10 min). The late response was recorded 20 min after formalin injection and lasted for 10 min (20-30 min). In the carrageenan-induced paw edema, both extracts revealed dose-related inhibitory effects on carrageenan-induced rat paw edema over the dose range 50-200 mg/kg. The anti-inflammatory activities of these extracts were similar to a high dose of indomethacin (5 mg/kg) in both carrageenan-induced paw edema and formalin-induced paw licking. In conclusion, the present data provide further evidence for an important role of extracts of Stachys byzanthina C. Koch. in the inhibition of pain and inflammatory processes.

Drug-induced toxic reactions in the eye: an overview

Every drug can produce untoward consequences, even when used according to standard or recommended methods of administration. Adverse drug reactions can involve every organ and system of the body, even the eye, and frequently are mistaken for signs of underlying disease. Reactions in the eye may involve the eyelids, periorbital tissues, lacrimal apparatus, conjunctiva, cornea, lens, iris, ciliary body, intraocular pressure, retina, optic nerve, and ocular movement. In addition, fetal abnormalities can be caused by the use of eye drugs during pregnancy. Topical ophthalmic therapies or the use of ophthalmic dyes may cause systemic reactions. This article reviews drugs used systemically or topically that may cause adverse effects in the eye and related structures. Adverse ocular reactions to medications create an important health problem, and nursing professionals in close contact with patients inside and outside the hospital must assume a role in detecting them early, identifying them, educating the patient about them, and treating them.

Posttraining intrahippocampal infusion of a protein kinase AII inhibitor impairs spatial memory retention in rats

The role of protein kinase AII (PKA II) in spatial memory retention in male rats and its regulation of cholinergic gene expression were explored through the effects of intrahippocampal infusion of H-89, a selective PKA II inhibitor. Alterations in escape latency, travel distance, and swimming speed in a Morris water maze were measured. Animals were trained for 3 days; each day included two blocks, and each block contained four trials. Stereotaxic surgery was employed for the infusions after the last trial on the third day of training, and the animals were tested 48 hr after surgery. Bilateral intrahippocampal infusion of H-89 (2.5 or 5 microM) into the CA1 region generated significant alterations in escape latency and traveled distance but not swimming speed. The response was fairly dose dependent, and the maximal effect was obtained with 5 microM H-89. After behavioral testing, several of the infused animals were transcardially perfused and their brains removed. Brain tissue sections from these rats were subjected to immunohistochemical staining analysis with anticholine acetyltransferase (ChAT) antibodies. These analyses indicated that 5 microM H-89 infusions qualitatively reduced the density of ChAT-containing cholinergic nerve terminals in the dorsal hippocampus. The intrahippocampal infusions with 5 microM H-89 also caused an apparent reduction in the number of ChAT-containing neurons in the medial septum. Our results suggest that PKA II is involved in regulation of cholinergic gene expression and plays an important role in spatial memory retention in rats.

Nitric oxide agents and apomorphine-induced rat behaviors

BACKGROUND

Nitric oxide (NO) may alter dopamine release in the brain. Activation of D2-dopamine receptors may suppress NO synthase, and inhibition of NO synthase prevents behaviors induced by psychostimulants. We have investigated the modulatory actions of the precursor of NO synthesis (L-arginine) and the broad-spectrum NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on apomorphine-induced behaviors in the rat.

METHODS

Apomorphine was injected subcutaneously, and behaviors induced by the drug were examined in the presence or absence of intracerebroventricular administration of L-arginine and L-NAME.

RESULTS

Our data indicate that L-arginine or L-NAME treatment decreased licking and yawning, but not penile erection induced by apomorphine.

CONCLUSION

Apomorphine-induced behaviors may be modulated by NO levels.

Anti-inflammatory effects of butadiene Diels-Alder adducts to some 1-dehydroglucocorticoids in rats

Three compounds (C1, C2 and C3) were synthesized by reacting dexamethasone as a strong anti-inflammatory drug or prednisolone as a moderate one with 1,3-butadiene under Diels-Alder reaction conditions to produce pentacyclic compounds. The structures of C1 [(11 beta,16 alpha,17 alpha)-9 alpha-fluoro-11,17,21-trihydroxy-16-methyl pregna [1 alpha,2 beta]-cyclohex 3',4-diene, 3,20-dione], C2 [(11 beta,16 alpha,17 alpha)-9 alpha-fluoro-11,17,21-trihydroxy-16-methyl pregna [1 alpha,2 alpha]-cyclohex 3',4-diene, 3,20-dione], and C3 [(11 beta,17 alpha)-11,17,21-trihydroxy-pregna [1 alpha,2 alpha]-cyclohex 3',4-diene, 3,20-dione] were concluded based on GC-mass and 1H NMR spectroscopic data. The compounds were used to evaluate the effect of introducing extra ring in the structure of the above drugs on their anti-inflammatory behavior. The potencies of the three compounds were compared with that of the mother drugs by the rat hind paw edema test. The results indicate a decrease in C1 potency, expressed as percentage of inflammation inhibition (16.5% versus 24.3% for Dex) or loss of C2 potency (2.0% versus 24.3% for Dex) in dexamethasone adducts. On the other hand, although the prednisolone adduct C3 lost potency too (3.95% versus 26.3% for Pred), but instead it lowered significantly the prednisolone potency on subsequent administration before prednisolone (C3+Pred) (1.30% versus 17.10% for Pred). When prednisolone was administered in equal doses after C3 (10mg/kg), it restored about 60% of its activity. This observation indicates that C3 still retain affinity toward GR without eliciting subsequent events. In other words it has anti prednisolone effect, i.e. anti-glucocorticoid property.

Gamma irradiator dose mapping simulation using the MCNP code and benchmarking with dosimetry

The Monte Carlo transport code, MCNP, has been applied in simulating dose rate distribution in the IR-136 gamma irradiator system. Isodose curves, cumulative dose values, and system design data such as throughputs, over-dose-ratios, and efficiencies have been simulated as functions of product density. Simulated isodose curves, and cumulative dose values were compared with dosimetry values obtained using polymethyle-methacrylate, Fricke, ethanol-chlorobenzene, and potassium dichromate dosimeters. The produced system design data were also found to agree quite favorably with those of the system manufacturer's data. MCNP has thus been found to be an effective transport code for handling of various dose mapping excercises for gamma irradiators.

Role of nitric oxide in systemic effect of theophylline on mouse body temperature

In the present study, the interaction of nitric oxide synthase (NOS) inhibitors, L-NAME (N(G)-nitro-L-arginine methyl ester HCl) and L-NA (N(omega)-nitro-L-arginine), and its precursor, L-arginine (2-(S)-2-amino-5-[(aminoiminomethyl)amino] pentatonic acid), with theophylline on mouse body temperature was studied. Intraperitoneal (i.p.) injection of different doses of theophylline altered body temperature. Lower doses of theophylline (12.5 and 25 mg/kg) increased, but a higher dose (100 mg/kg) reduced, the animals' body temperature. The combination of L-arginine (20 and 40 mg/kg) with the highest dose of theophylline potentiated the hypothermic effect induced by the latter drug, while L-arginine by itself did not alter body temperature. L-NAME (10-80 mg/kg) or L-NA (10 mg/kg) plus a lower dose of theophylline (12.5 mg/kg) reduced the theophylline-induced hyperthermic response. L-NA (1, 5, and 10 mg/kg) in combination with the high dose of theophylline (100 mg/kg) also induced greater hypothermia. Both L-NAME and L-NA by themselves reduced body temperature. It is concluded that nitric oxide (NO) may be involved in the effects of theophylline on body temperature in mice.

Effects of subacute lead acetate administration on nitric oxide and cyclooxygenase pathways in rat isolated aortic ring

Low level exposure to lead increases blood pressure in human and rats. In this study, we investigated the contribution of the nitric oxide (NO) and cyclooxygenase pathways of aortic rings of 28-day lead-treated and control rats, to the responsiveness to phenylephrine and acetylcholine. There were no differences in phenylephrine contractions between the two groups. N(omega)-nitro-L-Arginine-methyl ester (L-NAME), a NO synthase inhibitor, caused attenuation in contraction response to phenylephrine in the aortic rings of the lead-treated rats, while endothelium-denudation caused attenuation in those of controls. This may be due to either endothelium-derived vasoconstrictor(s) (such as reactive oxygen species or endothelins) or a source of NO in smooth muscle cells. There is a left-shift in acetylcholine relaxation response. Indomethacin incubation caused a left-shift in relaxation response to acetylcholine in controls but without any effect on lead-treated ones. Indomethacin incubation caused attenuation in contraction to phenylephrine in both groups. The relaxation response to sodium nitroprusside is not different between the two groups, suggesting that smooth muscle relaxation component is intact. However, the relaxation response to glyceryl trinitrate is impaired in aortic rings of lead-treated rats. It can be concluded that NO and cyclooxygenase pathways are altered in aortic rings of lead-treated rats, with possible involvement of endothelium-derived vasoconstrictors.

Effects of different periods of lithium pretreatment and aminoglycoside antibiotics on apomorphine-induced yawning in rats

Interactive effects of intracerebroventricular administration of the aminoglycoside antibiotics, amikacin and gentamicin, and different duration of lithium pretreatment on apomorphine-induced yawning were investigated in male rats. The study was designed to investigate whether the hypothesis that the aminoglycoside antibiotics, amikacin and gentamicin, via their effects on phosphoinositide pathways and calcium channel might influence dopaminergic mechanisms as manifested in the yawning effect. Lithium is known to interact with phosphoinositide metabolism and was also tested after chronic studies on the apomorphine yawning model. Subcutaneous administration of apomorphine (0.1, 0.2 and 0.4 mg/kg) to rats induced yawning in a biphasic manner. However the maximum response was obtained by 0.2 mg/kg of the drug. Intracerebroventricular administration of aminoglycoside antibiotics amikacin (25 microg/rat) increased and gentamicin (10 and 20 microg/rat) decreased apomorphine-induced yawning. Pretreatment of animals with lithium (600 mg/l) in drinking water for 7, 14 and 21 days reduced yawning induced by apomorphine. Administration of lithium for 28 days did not induce any significant effect on yawning response. Amikacin and gentamicin function via the same mechanism on phosphoinositide cascade. Since amikacin and gentamicin did not affect the yawning response similarly, they apparently do not involve inositol trisphosphate level in the alterations of dopaminergic-induced yawning. Probably, the effect of lithium pretreatment on the number of yawns is also time-dependent and some tolerance to the inhibitory effect of lithium might occur after 28 days' treatment.

Muscle relaxant activity of methocarbamol enantiomers in mice

Documented studies support the emerging idea that drug enantiomers could have different pharmacological activity. Our bibliographical data have shown that so far no report has been published on the pharmacological activity of individual enantiomers of methocarbamol. This study was conducted to characterize the muscle relaxant activity of methocarbamol enantiomers. The rotarod test was used to compare the muscle relaxant activity of racemic methocarbamol and pure enantiomers after intraperitoneal administration of the enantiomers to mice. The results show that (+)-R-methocarbamol has higher muscle relaxant activity compared with racemic methocarbamol or (-)-S-methocarbamol.