Effectiveness of antagonists for tiletamine-zolazepam/xylazine immobilization in female white-tailed deer

A combination of tiletamine-zolazepam/xylazine (TZ/X) is effective in the chemical immobilization of white-tailed deer (Odocoileus virginianus); however, the lengthy duration of immobilization may limit its usefulness. From October to November 2002, 21 captive female deer were assigned randomly to an alpha(2) antagonist treatment to reverse xylazine-induced sedation (seven does per group). All deer were given 220 mg of TZ (4.5+/-0.4 mg/kg) and 110 mg of X (2.2+/-0.2 mg/kg) intramuscularly (IM). Antagonist treatments were either 200 mg of tolazoline (4.0+/-0.4 mg/kg), 11 mg of atipamezole (0.23+/-0.02 mg/kg), or 15 mg of yohimbine (0.30+/-0.02 mg/kg) injected, half intravenously and half subcutaneously, 45 min after the IM TZ/X injection. In addition, 10 other deer (five per group) were immobilized as before and then given tolazoline (200 mg) after 45 min, with either a carrier (dimethyl sulfoxide [DMSO]) or carrier (DMSO) plus flumazenil (5 mg) to reverse the zolazepam portion of TZ. Mean times from antagonist injection until a deer raised its head were different for alpha(2) antagonist treatments (P=0.02). Times were longer for yohimbine (62.3+/-42.7 min) than for either atipamezole (24.3+/-17.1 min) or tolazoline (21.3+/-14.3 min). Mean times from antagonist injection until standing were not different (P=0.15) among yohimbine (112.0+/-56.4 min), atipamezole (89.7+/-62.8 min), or tolazoline (52.6+/-37.2 min). A sedation score based on behavioral criteria was assigned to each deer every 30 min for 5 hr. On the basis of sedation scores, tolazoline resulted in a faster and more complete reversal of immobilization. Flumazenil treatment did not affect recovery.     

Total intravenous anesthesia with midazolam, ketamine, and xylazine or detomidine following induction with tiletamine, zolazepam, and xylazine in red deer (Cervus elaphus hippelaphus) undergoing surgery

Sixteen captive female red deer were successfully anesthetized to surgically implant a telemetry system. The deer were immobilized with (mean±SD) 1.79±0.29 mg/kg xylazine and 1.79±0.29 mg/kg tiletamine/zolazepam given intramuscularly with a dart gun. Anesthesia was maintained for 69±2 min using a total intravenous protocol with a catheter placed in the jugular vein. Group X received xylazine (0.5±0.055 mg/kg/hr) and group D, detomidine (2±0.22 μg/kg/hr), both in combination with ketamine (2±0.02 mg/kg/hr) and midazolam (0.03±0.0033 mg/kg/hr), as a constant rate infusion. Anesthesia was reversed with 0.09±0.01 mg/kg atipamezole and 8.7±1.21 μg/kg sarmazenil given intravenously in both groups. These drug combinations provided smooth induction, stable anesthesia for surgery, and rapid recovery. Respiratory depression and mild hypoxemia were seen, and we, therefore, recommend using supplemental intranasal oxygen.     

Effects of an anesthetic mixture of medetomidine,midazolam, and butorphanol in rats—strain difference and antagonism by atipamezole

An anesthetic mixture of medetomidine (MED), midazolam (MID), and butorphanol (BUT) has been used in laboratory animals. We previously reported that this anesthetic mixture produced closely similar anesthetic effects in BALB/c and C57BL/6J strains. We also demonstrated the efficacy of atipamezole (ATI), an antagonist of MED that produced quick recovery from anesthesia in mice. Anesthetics have various anesthetic effects among animal strains. However, the differences in the effects of anesthetic mixtures in rats are unclear. In the present study, we first examined effects of the abovementioned anesthetic mixture using three different rat strains: Wistar (WST), Sprague-Dawley (SD), and Fischer 344 (F344). Second, we examined how different dosages and optimum injection timing of ATI affected recovery from anesthesia in rats. We used the anesthetic score to measure anesthetic duration and a pulse oximeter to monitor vital signs. We found no significant differences in anesthetic duration among the three different strains. However, recovery from anesthesia in the SD strain took significantly longer than in the other strains. The antagonistic effects of ATI (0.15 mg/kg and 0.75 mg/kg) were equivalent when administered at 30 min after anesthetic mixture administration. The antagonistic effects of ATI 0.75 mg/kg were stronger than those of ATI 0.15 mg/kg at 10 min after anesthetic mixture administration. This anesthetic mixture is a useful drug that can induce similar anesthetic effects in three different strains and has an antagonist, ATI, that makes rats quickly recover from anesthesia. These results may contribute to the welfare of laboratory animals.     

Anesthetic effects of a three-drugs mixture —comparison of administrative routes and antagonistic effects of atipamezole in mice—

The anesthetic mixture of medetomidine (MED), midazolam (MID) and butorphanol (BUT) produced anesthetic duration of around 40 minutes (min) in ICR mice. We reported that this anesthetic mixture produced almost the same anesthetic effects in both male and female BALB/c and C57BL/6J strains. Intraperitoneal (IP) administration of drugs has been widely used in mice. However, various injectable routes of the anesthetic mixture may cause different anesthetic effects. First, we examined effects of the anesthetic mixture by subcutaneous (SC) and intravenous (IV) injection compared to IP injection. After injection of the anesthetic mixture, administration of atipamezole (ATI) induced mice recovery from anesthesia. Secondly, we examined how different dosage and optimum injection timing of ATI affected mice recovery from anesthesia. We used an anesthetic score to measure anesthetic duration and a pulse oximeter to monitor vital signs under anesthesia. Usually, drugs from SC injection work more weakly than IP or IV injection. However, we found no significant differences of anesthetic duration among the three different injection routes. Antagonistic effects of ATI (0.3 mg/kg and 1.5 mg/kg) worked equally when administered at 30 min after injection of the anesthetic mixture. Antagonistic effects of ATI (1.5 mg/kg) were stronger than ATI (0.3 mg/kg) at 10 min after injection of the anesthetic mixture. The anesthetic mixture is a useful drug to induce nearly the same anesthetic effects by different injection routes and has an antagonist of ATI which helps mice quickly recover from anesthesia. These results may contribute to the welfare of laboratory animals.     

Behavioral effects of benzodiazepine antagonists in chlordiazepoxide tolerant and non-tolerant rats

Rats were trained to respond under 3-min fixed-interval schedules of food presentation, and effects of the benzodiazepine-receptor ligands, flumazenil, 2-(4-methoxy-phenyl)-pyrazolo[4,3-c]quinolin-3(5H)-one (CGS 9895), 3-carbo-t-butoxy-beta-carboline (beta-CCtB), and beta-carboline-3-carboxylic acid ethyl ester (beta-CCE) were assessed before and after the induction of tolerance to chlordiazepoxide. Before daily administration of chlordiazepoxide, none of the antagonists produced appreciable effects on rates of responding up to doses of 32.0 mg/kg i.p. beta-CCE was the only antagonist studied at a higher dose (100.0 mg/kg i.p.), which decreased response rates. After 23 days of daily chlordiazepoxide administration (oral doses started at 10 and increased to 100 mg/kg/day by the 17th day), dose-effect curves for chlordiazepoxide were shifted to the right by about one-half log unit. Subjects were also more sensitive to the flumazenil, CGS 9895, and beta-CCtB, however, since these drugs produced only small effects in non-tolerant subjects, precise estimates of the degree of the shift in dose-effect curves could not be estimated. However, there were differences in the changes in the dose-effect curves induced by chlordiazepoxide tolerance. These results suggest differences in mechanism of action of antagonists in tolerant and non-tolerant subjects, and further that the sensitivity that is induced to antagonists in tolerant subjects is not conferred equally to all drugs having benzodiazepine antagonist activity.     

Comparative immobilization of wild felids in Thailand

We immobilized individuals of four free-ranging felid species, leopard cat (Prionailurus bengalensis), clouded leopard (Neofelis nebulosa), Asiatic golden cat (Catopuma temminckii), and marbled cat (Pardofelis marmorata) with ketamine hydrochloride and xylazine hydrochloride (KH-XH) and with tiletamine hydrochloride and zolazepam hydrochloride (TH-ZH) between March 1998 and July 2002. Mean (+/-SD) dose of KH and XH was 26.51+/-5.71 mg/kg and 1.89+/-0.43 mg/kg, respectively (n=25), and mean dose of TH-ZH was 11.61+/-3.39 mg/kg (n=28). Dose was significantly correlated with induction time (P<0.001) and duration of anesthesia (P<0.05), but not with recovery time. There were significant differences between the drug combinations in time to induction (P<0.03) and time to anesthesia (P<0.01); recovery times were not significantly different. We conclude that immobilization of these felids with TH-ZH and KH-XH is effective and safe, but TH-ZH is preferred because of the smaller volume of drug necessary for sedation, faster time to induction, and absence of prolonged muscle rigidity during anesthesia.     

The use of propofol for electroejaculation in domestic cats

The objective was to evaluate the use of propofol as an anesthetic drug for electroejaculation in the domestic cat. Cortisol concentrations, heart rates and respiratory rates of 20 male domestic cats were examined. The animals were randomly allocated into three groups. Group A (n = 8), were anesthetized with propofol (10 mg/kg) and underwent electroejaculation. Group B (n = 6), were pre-medicated with buprenorphine (0.01 mg/kg), anesthetized with propofol (5 mg/kg) and underwent electroejaculation. Group C (n = 6), the cats were anesthetized with propofol (10 mg/kg) without electroejaculation (control group). Blood samples were collected at four time points (30 min before propofol administration, immediately after the surgical plane of anesthesia was induced, immediately post-electroejaculation, and at the onset of anesthetic recovery). In the control group, the sampling time coincident with the end of electroejaculation was assigned as 21 min after the induction of anesthesia. The mean (+/- S.E.M.) duration time for electroejaculation was 18 +/- 3 min. The duration of anesthesia did not differ (P > 0.05) among the three groups of cats (26 +/- 2 min). Most of the cats (17/20) recovered smoothly. Pre-anesthetic medication with buprenorphine did not reduce the requirement of propofol for anesthesia. The cortisol concentrations, heart rates and respiratory rates of the three groups of cats did not differ (P > 0.05). A marked decline in cortisol levels was observed immediately post-electroejaculation. Propofol was a useful anesthetic for electroejaculation in felids with rapid onset, optimal duration of anesthesia for performing electroejaculation, and smooth recovery.     

Intracelomic use of tricaine methanesulfonate for anesthesia of bullfrogs (Rana catesbeiana) and leopard frogs (Rana pipiens)

The use of intracelomic injection of dissolved tricaine methanesulfonate (MS-222) as an anesthetic agent in two anuran species was studied. Intracelomic MS-222, at dosages of 100, 250, and 400 mg/kg, rapidly induced tranquilization or anesthesia. Effects were less pronounced or nonexistent at the 50 mg/kg dosage. Depth and duration of anesthesia were dosage related. At the 100, 250, and 400 mg/kg dosages, Rana pipiens attained a greater depth of anesthesia and remained anesthetized for a significantly greater duration than did R. catesbeiana. Dosages of between 250–400 mg/kg reliably induced deep anesthesia without mortality in bullfrogs. Dosages of less than 250 mg/kg are recommended for leopard frogs, since variable mortality was noted with higher dosages. Solubilized tricaine methanesulfonate did not cause gross or histopathological lesions to celomic tissues. Tricaine methanesulfonate injected intracelomically can provide rapid, efficient anesthesia in some anuran species. However, due to the observed intra- and interspecies variation in effect, it should be used cautiously, especially in unfamiliar species. © 1992 Wiley-Liss Inc.     

Effects of GABA(A) compounds on mCPP drug discrimination in rats

Male Long-Evans rats were trained to discriminate mCPP (1.4 mg/kg, i.p.) from saline, using a two-lever, food-reinforced operant task. The GABA(A) antagonist, bicuculline (0.16-0.64 mg/kg), partially substituted for mCPP, whereas the benzodiazepine antagonist, flumazenil (1-10 mg/kg), and the benzodiazepine inverse agonist, Ro 15-4513 (0.25-2.5 mg/kg), failed to substitute for mCPP. Bicuculline produced no change in response rate, whereas Ro 15-4513 dose-dependently decreased responding. Flumazenil produced a small increase in response rates. Flumazenil (10 mg/kg), Ro 15-4513 (1.25 mg/kg), and the benzodiazepine agonists alprazolam (0.64 mg/kg) and diazepam (5 mg/kg) full agonist all failed to block the mCPP discriminative stimulus. When given in combination with mCPP, Ro15-4513 and alprazolam both produced lower response rates than did mCPP alone, whereas flumazenil and diazepam did not significantly alter response rates. These findings provide evidence that GABA(A) antagonists modulate the discriminative stimulus effects of mCPP, but that these effects are not mediated by activity at the benzodiazepine site.     

Flumazenil and bupivacaine-induced toxicity: inverse agonist type activity

The purpose of this study was to investigate the influence of flumazenil on bupivacaine-induced acute toxicity, 10 groups of mice were previously treated by a 1, 0.5, 0.25 and 0.125 mg/kg single dose of flumazenil or saline 15 minutes before an injection of bupivacaine (50 mg/kg: exp. 1 and 60 mg/kg: exp.2). The convulsant activity, the period of latency to convulse and the induced mortality were assessed in each group. The bupivacaine-induced mortality was increased by flumazenil. Also, the convulsant activity was increased by flumazenil and the period of latency to convulse was proportionally decreased with increasing doses of flumazenil for the two tested doses of bupivacaine.     

Evaluation of two combinations of Domitor, Zoletil 100, and Euthatal to obtain long-term nonrecovery anesthesia in Sprague-Dawley rats

We sought to evaluate a new protocol designed to maintain long-term, nonrecovery, surgical anesthesia in Sprague-Dawley rats. In the first phase, two groups of rats were anesthetized with two different dose combinations of Domitor (medetomidine) and Zoletil 100 (tiletamine-zolazepam) to investigate their efficacy in induction of anesthesia. One combination comprised Domitor at 35 microg/kg and Zoletil 100 at 40 mg/kg, whereas the other comprised Domitor at 50 microg/kg and Zoletil 100 at 20 mg/kg. Both combinations effectively induced deep anesthesia and caused no mortality, but the duration of anesthesia differed statistically. In the second phase, we induced anesthesia with both Domitor-Zoletil 100 dose combinations then investigated the possibility of maintaining anesthesia for 5 h by administering Euthatal (pentobarbitone) intra-arterially at 10 mg/kg hourly. Depth of anesthesia, mortality, physiological parameters, blood gas analysis, hematology, clinical chemistry, and postmortem histopathology were recorded. Euthatal provided stable long-term anesthesia with both dose combinations of Domitor-Zoletil 100. Seven of 8 (88%) animals anesthetized with Domitor at 50 microg/kg and Zoletil 100 at 20 mg/kg successfully were maintained under deep anesthesia for 5 h. Higher mortality (36% versus 12%) occurred in group of animals treated with Domitor at 35 microg/kg and Zoletil 100 at 40 mg/kg. This difference may be linked to dose-related respiratory depression, as alterations of arterial gas levels were noted. Our findings suggest that, when long-term nonrecovery anesthesia is required, doses of 50 microg/kg Domitor and 20 mg/kg Zoletil 100 are preferable when given with Euthatal to maintain physiological conditions in animals.     

Behavioral effects of acute and chronic triazolam treatments in albino rats

Previous behavioral studies on triazolam (TZ), which are small in number, could only speculate about tolerance to the anxiolytic effect of TZ, as the experiments did not cover sufficient time (of 4 to 7 days) for tolerance to develop. Therefore longer time for chronic TZ administration is used. We investigated the effects of TZ on motor activity and exploratory behavior using plus maze and open field. Three experiments were conducted. In the first, five groups of rats were acutely treated with different doses of TZ (0.25 mg/kg-4.0 mg/kg). In the second set of experiments, rats were treated chronically with a single daily dose of TZ (started with 0.25 mg/kg and increased by time to 1.0 mg/kg) for 5 weeks (representing clinical use). In the third, rats were treated chronically with three daily doses of TZ (started with 0.25 mg/kg and increased by time to 0.5 mg/kg) for 20 days (mimicking drug abuse). Acute TZ administration produced dose dependent anxiolytic effects and a decrease in motor activity with higher doses. Chronically treated rats, either once daily or three times daily doses, showed tolerance to both anxiolytic and sedative effects of TZ. It may be concluded that tolerance to the anxiolytic and sedative effects of TZ would develop after chronic administration either with clinical use or its abuse.     

Immobilization of free-ranging Hoffmann's two-toed and brown-throated three-toed sloths using ketamine and medetomidine: a comparison of physiologic parameters

Free-ranging Hoffmann's two-toed sloths (Choloepus hoffmanni; n=26) and brown-throated three-toed sloths (Bradypus variegatus; n=15) were manually captured and immobilized with 2.5 mg/kg ketamine + 0.02 mg/kg medetomidine administered intramuscularly. Physical examinations were conducted on each sloth 10 min after initial injection, and blood, fecal, and ectoparasite samples were collected. Heart rate, respiratory rate, body temperature, indirect systolic blood pressure, and indirect peripheral oxygen saturation were monitored every 5 min for the duration of anesthesia. After 45 min, atipamazole (0.1 mg/kg) was administered intramuscularly, as an antagonist to medetomidine, in order to facilitate recovery. All recoveries were smooth, rapid, and uneventful. Physiologic parameters were compared across time, gender, and species. All sloths, regardless of species and gender, demonstrated a time-dependent decrease in heart rate and blood pressure, and an increase in respiratory rate, during the course of anesthesia. Peripheral oxygen saturation was similar for all sloths over time. There were significant species differences for heart rate (Choloepus > Bradypus), respiratory rate (Choloepus > Bradypus), and systolic blood pressure (Bradypus > Choloepus), while there were significant gender differences for body temperature (males > females) and blood pressure (males > females). Results of this study suggest that the ketamine-medetomidine mixture, as described above, is a safe and effective anesthetic combination in free-ranging two- and three-toed sloths, although peripheral blood pressure should be monitored during anesthesia.     

Local anesthetic-induced toxicity may be modified by low doses of flumazenil.

The purpose of this study was to investigate the influence of flumazenil on local anesthetic-induced acute toxicity. For each of the three tested anesthetics (etidocaine, mepivacaine and lidocaine) 6 groups of mice were treated by a single dose of flumazenil (0.125, 0.25, 0.5, 1 and 2 mg/kg), or an equal volume of saline, 15 minutes before the injection of the anesthetic (etidocaine: 50 mg/kg, mepivacaine: 110 mg/kg and lidocaine: 115 mg/kg). The convulsant activity, the time of latency to convulse and the mortality rate were assessed in each group. The local anesthetic-induced mortality was not significantly modified by flumazenil. The convulsant activity of lidocaine and mepivacaine was significantly increased by flumazenil but not for etidocaine. Also, increasing doses of flumazenil decreased the time of latency to obtain lidocaine-induced convulsions. This effect was not obtained with etidocaine or mepivacaine.     

A comparison of ketamine/xylazine and ketamine/xylazine/acepromazine anesthesia in the rabbit

Parenteral anesthetic combinations such as ketamine and xylazine have become the agents of choice for anesthesia in the rabbit, because they are effective, easily administered and inexpensive. A number of recent reports have recommended including acepromazine in this combination, but a critical evaluation of this combination in the rabbit has not been reported. Five adult New Zealand white rabbits were anesthetized intramuscularly with ketamine (35 mg/kg) and xylazine (5 mg/kg) with or without acepromazine (0.75 mg/kg). The study was conducted in a double blind fashion, where each rabbit was administered both combinations at a minimum of 7 day intervals. Physiologic parameters were evaluated including heart rate, respiratory rate, central arterial blood pressure, pedal, palpebral and postural reflex activity. The duration of general anesthesia, estimated by the time elapsed between the loss and return of the palpebral reflex, was greater (means = 99 +/- 20 minutes) when acepromazine was employed in the combination compared to (means = 77 +/- 5 minutes) when ketamine/xylazine were used alone. Mean central arterial blood pressure reached a lower level when acepromazine was utilized (means = 46 +/- 8 mm/Hg) than when it was not (means = 57 +/- 12 mm/Hg.). The addition of acepromazine in a ketamine/xylazine combination resulted in a 28% longer period of anesthesia, a 19% lower mean central arterial blood pressure and a 32% longer recovery of postural reflexes. The ketamine/xylazine/acepromazine combination is a useful regimen for normovolemic animals when anesthetic duration greater than that produced by ketamine/xylazine alone is required.     

Similar effects of a beta-carboline and of flumazenil in negatively and positively reinforced learning tasks in mice.

Methyl beta-carboline-3-carboxylate (beta-CCM) and flumazenil (Ro15-1788) are known to be respectively an inverse agonist and an antagonist of the central benzodiazepine-receptor. Surprisingly, these two drugs have shown a similar enhancing effect in a negatively reinforced multiple-trial brightness discrimination task in mice. Thus, to evaluate the role of anxiety in this task, the action of these two drugs were compared in the same learning task with a positive or a negative reinforcement. Mice were trained for sessions of ten trials per day for six consecutive days. The sessions during the first three days took place after administration of beta-CCM (0.3 mg/kg), flumazenil (15 mg/kg) or vehicles of these drugs. A negative reinforcement (electric foot-shock) was used in a first experiment, and a positive one (food reward) in a second experiment. Results showed that, whatever the reinforcement, the two drugs enhance learning in a brightness discrimination task. The hypothesis is that flumazenil could have an inverse agonist profile in learning tasks. The question remains as to whether the flumazenil enhancing learning process results from increased arousal and/or anxiogenic factors, or from a negative modulatory influence of endogenous diazepam-like ligands for benzodiazepine receptors.     

Effect of withdrawal of diazepam or morphine treatment on gastric motility (charcoal meal test) in mice: possible role of different central and peripheral receptors

Increased gastrointestinal motility in mice as one of the withdrawal symptoms of commonly abused drugs like diazepam or morphine and its possible mechanism of action was studied. Male Laka mice (20-25 g) were made addict to either diazepam (20 mg/kg, ip for 7 days) or morphine (10 mg/kg, sc for 9 days). Withdrawal symptoms were noted 24 hr after the last injection of diazepam or morphine. The animals were injected with Ro 15-1788 (flumazenil) (1 mg/kg, ip) or naloxone (2 mg/kg, ip) in the respective group to precipitate the withdrawal symptoms. Gastrointestinal motility was assessed by charcoal-meal test. Animals developed tolerance to acute sedative effect of diazepam, and similarly to the acute nociceptive action of morphine. On abrupt cessation of these drugs after chronic treatment the animals showed hyperlocomotion and hyperreactivity in diazepam withdrawal group and hyperalgesia on hot plate in morphine withdrawal groups, respectively. Increase in gastrointestinal motility was observed in all the drug withdrawal groups. Treatment with respective antagonists, Ro 15-1788 (flumazenil) and naloxone precipitated the withdrawal symptoms. The results suggest the involvement of both central and peripheral receptors of benzodiazepines and opioid (mu) receptors in the withdrawal symptoms of the benzodiazepines and morphine, respectively.     

USE OF A PETHIDINE AND MIDAZOLAM COMBINATION FOR THE REVERSIBLE SEDATION OF CRABEATER SEALS (LOBODON CARCINOPHAGUS)

Between October and December of 1996–1999, off eastern Antarctica (60°-150°E), we darted 31 crabeater seals with midazolam and pethidine at estimated dose rates of 0.15–0.4 mg/kg and 1–3 mg/kg, respectively. Maximum sedation was reached at 23 ± 9 min (n = 18) and first signs of recovery were noted at 54 ± 24 min (n = 4). Seals greater than 250 kg body-mass were sedated by administration of approximately 90–100 mg midazolam and 600 mg pethidine, but the degree of sedation was unpredictable and did not permit invasive procedures in some cases. Behavior of the seal and adjacent conspecifics affected the success of procedures and our ability to monitor vital signs. Naloxone and flumazenil reversed sedation, making this combination attractive for use in animals adjacent to water. Additional ketamine was administered to two seals, resulting in improved restraint.     

Cardiopulmonary,hematological, serum biochemical and behavioral effects of sevoflurane compared with isoflurane or halothane in spontaneously ventilating goats

This study compares cardiopulmonary, hematological, serum biochemical and behavioral effects of sevoflurane, isoflurane or halothane anesthesia in spontaneously breathing, conventionally medicated goats. Six male adult goats were anesthetized repeatedly at 2-week intervals with three anesthetics. Goats were administered atropine (0.1 mg/kg) intramuscularly, and 10 min later, induced to anesthesia by an intravenous infusion of thiopental (mean 14.3 mg/kg). After intubation, goats were anesthetized with halothane, isoflurane or sevoflurane in oxygen and maintained at surgical depth of anesthesia for 3 h. Recovery from anesthesia with sevoflurane was more rapid than that with isoflurane or halothane. Time-related hypercapnia and acidosis were observed during halothane anesthesia, but not observed during sevoflurane or isoflurane anesthesia. Both hypercapnia and acidosis during sevoflurane anesthesia did not differ from isoflurane anesthesia, but were less during halothane anesthesia, especially at prolonged maintenance period. There were no significant differences between anesthetics in respiration and heart rates, arterial pressures, hematological and serum biochemical values. It was concluded that sevoflurane is an effective inhalant for use in goats showing the most rapid recovery from anesthesia, and that cardiopulmonary effects of sevoflurane are similar to isoflurane than halothane.     

Anaphe venata larva extract-induced purposeless chewing in rats: the role of cholinergic, GABAergic and opioid systems

Seasonal ataxia was reported in humans following the consumption ofAnaphe venata larva as protein supplement in diet and altered motor function in rodents when the extract was administered intraperitoneally. In this study we investigated the effect of the crude aqueous and Phosphate Buffer Saline (PBS) extracts of this larva on altered spontaneous rat behavior in a novel environment particularly chewing behaviour, with a view to determine the mechanism(s) involved in these behavioural alteration. Animals were randomly assigned into four groups (n = 6-12 per group) and graded doses of aqueous and PBS extracts (100-400 mg/kg) were administered dissolved in saline intraperitoneally (i.p.) to each animal in the experimental groups. The control group received an equivalent volume of saline. Behavioral scores were recorded for a period of 30 minutes after the administration of saline or extract. The role of various receptors in the extract induced chewing was evaluated using known receptor agonist/antagonists. Results revealed a significant increase in purposeless chewing (F (7, 95) = 7.85; p <0.05) by the aqueous extract compared to saline control at all dose levels, which was significantly attenuated by scopolamine (3 mg/kg, i.p) and thiamine (1 mg/kg, i.p) respectively (p <0.05); while flumazenil (2 mg/kg, i.p) and naloxone (2.5 mg/kg, i.p) did not alter the induced purposeless chewing behaviour. Also, administration of PBS induced a significant (F (7, 95) = 6.11; p <0.05) increase in chewing behaviour but only at 400 mg/kg dose level which was attenuated by scopolamine (3 mg/kg, i.p); while flumazenil (2 mg/kg, i.p), naloxone (2.5 mg/kg, i.p), and thiamine (1 mg/kg, i.p) potentiated purposeless chewing behaviour respectively. It may therefore be concluded from this study that Anaphe extract-induced purposeless chewing behaviour in rat is mediated via the activation of cholinergic neurotransmission which is modulated by GABAergic and opioid receptor systems.