Rectal administration of N-acetylcysteine in swine: a pilot study.

The purpose of this pilot study was to determine if N-acetylcysteine (NAC) administered via the rectal route in swine is absorbed into the systemic circulation. Fasting swine were anesthetized, intubated, monitored and i.v. access was obtained by femoral cutdown. NAC was administered into the rectal vault (2.0 g/kg) via a balloon-tipped Foley catheter inserted into the animals' rectum. NAC administered via the rectal route resulted in systemic absorption as determined by spectrophotometric methods in 5 of the 7 study animals. This study provides important information regarding the development of a potential alternative route for the administration of NAC.

The interaction of dopamine, cocaine, and cocaethylene with ethanol on central nervous system depression in mice.

The interactions between dopamine, cocaine, cocaethylene, and ethanol were studied in Swiss-Webster mice. The loss of the righting reflex (LORR) was used as a measure of CNS depression. Animals were injected intraperitoneally (IP) with ethanol (4.0 g/kg). which caused a LORR. Immediately upon regaining of the righting reflex, mice were injected intracerebroventricularly (ICV) with saline, dopamine (0.1, 0.5, or 1.0 mumol/kg), cocaine (1, 15, or 25 mumol/kg), or cocaethylene (1, 15, or 25 mumol/kg). In the presence of systemic ethanol, all three compounds produced CNS depression in a dose-dependent manner. The dopamine D2-receptor antagonist sulpiride and the D1-receptor antagonist fluphenazine were given acutely ICV with dopamine in the presence of systemic ethanol to examine whether these antagonists could block the return to the LORR produced by dopamine. Sulpiride, however, actually enhanced the interaction between ethanol and dopamine in a dose-dependent manner as measured by the LORR; fluphenazine neither blocked nor enhanced the effect of dopamine in the presence of systemic ethanol. In addition, these antagonists had no effect on cocaine- and cocaethylene-induced CNS depression in the presence of systemic ethanol. The results of this study showed that the neurotransmitter dopamine and both cocaine and cocaethylene can promote further CNS depression in the presence of systemic ethanol, and that dopamine was significantly more potent than cocaine and cocaethylene as measured by the return to the LORR.

Glycine enhances the central depressant properties of ethanol in mice.

The interaction between ethanol and glycine in the central nervous system was investigated in male Swiss-Webster mice. The loss of the righting reflex (LORR) was used as a measure of central nervous system depression. Mice were injected with ethanol (4.0 g/kg, IP), causing an ethanol-induced LORR. Immediately after the animals regained the righting reflex from ethanol administration, they received an intracerebroventricular (ICV) injection of saline or glycine (1, 15, 25, or 50 mumol/kg) in a volume of 5 microliters. Upon ICV injection of glycine, the mice lost the righting reflex once again. This effect of glycine in the presence of ethanol occurred rapidly and in a dose-dependent manner. Glycine induced a return to the LORR of 12.6 +/- 0.7, 24.5 +/- 1.3, 32.8 +/- 2.0, and 46.8 +/- 4.5 min when doses of 1, 15, 25, and 50 mumol/kg, respectively, were injected. D-Serine (15, 25, or 50 mumol/kg), an amino acid precursor of glycine, was injected (ICV) after the animals regained the righting reflex following ethanol injection (IP). Serine caused a return to the LORR of 0.5 +/- 0.5, 6.0 +/- 1.0, and 6.5 +/- 0.9 min when doses of 15, 25, and 50 mumol/kg, respectively, were injected. Strychnine was used to attenuate the ability of glycine and serine to cause a return to the LORR in the presence of ethanol. Strychnine, a competitive antagonist of glycine, significantly reduced the ability of glycine and serine to enhance the depressant action of ethanol.(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of cocaine usage in pregnant women by a urinary EMIT drug screen and GC-MS analyses.

In mothers who had no prenatal care and in their newborns, the presence of cocaine and benzoylecgonine (BE) was determined in urine, hair, and meconium. Samples of urine and hair were obtained from pregnant women who entered the hospital for delivery. Cocaine usage was assessed by a urinary enzyme-multiplied immunoassay technique (EMIT) and by gas chromatography-mass spectrometry (GC-MS). GC-MS was used to detect the presence of cocaine and BE in maternal urine and hair and in meconium and hair obtained from their newborns. In this study of 40 women, the EMIT assay for urinary BE identified 17 (42.5%) of the women as having used cocaine. Of these 17 women, all of their newborns were exposed to cocaine during gestation, based on the analysis of neonatal hair and meconium for cocaine or BE. From the maternal samples that were assayed for cocaine and BE by GC-MS, it appears that hair analysis identified the most cocaine users (70%) of the 40 women who participated in the study. When GC-MS was used to analyze the various samples from mothers and their newborns, 80% of the neonates showed exposure to cocaine. This study shows that women with no prenatal care who have a positive urinary drug screen by EMIT for BE have exposed their newborns to cocaine. The data from pregnant women with a negative drug screen for BE show that 52.2% of their newborns had prior fetal exposure to cocaine.

Interaction between L-glutamate and ethanol on the central depressant properties of ethanol in mice.

The effect of L-glutamate to alter ethanol-induced central depression was studies in male Swiss-Webster mice. The duration loss of the righting reflex (LORR) was used as a measurement of CNS depression. Mice were injected (IP) with ethanol (4.0 g/kg), which caused them to lose the righting reflex. After mice regained the righting reflex following ethanol injection (IP), they were immediately injected (ICV) with saline or L-glutamate (1, 15, or 25 mumol/kg). L-Glutamate induced a return to the LORR within 60 s after ICV injection of drug. When L-glutamate was administered (ICV) in the absence of ethanol, no significant loss of the righting occurred. In other experiments, DL-2-amino-5-phosphonovaleric acid (APV), a competitive inhibitor of NMDA, was given ICV with L-glutamate in the presence of ethanol. APV did not significantly antagonize the interaction between ethanol and L-glutamate. When bicuculline methiodide, a GABA antagonists, was administered with L-glutamate (ICV), bicuculline methiodide reduced the effect of L-glutamate to produce a return to the LORR in the presence of ethanol. These data indicate the L-glutamate, an excitatory amino acid neurotransmitter, can enhance the central depressant action of ethanol. It appears that an interaction between the GABAergic and glutamatergic systems may be involved in ethanol intoxication.

NMDA enhances the central depressant properties of ethanol in mice.

Male Swiss-Webster mice were used to examine the effect of NMDA on the ethanol-induced loss of the righting reflex (LORR). The LORR was used as a measure of CNS depression. Immediately after animals regained the righting reflex following ethanol injection (4.0 g/kg, IP) mice received an ICV injection of saline or NMDA (10, 50, 100, or 500 nmol/kg) in a volume of 5 microliters. Upon ICV injection of NMDA, mice again lost the righting reflex and this effect of NMDA in the presence of ethanol occurred rapidly and in a dose-dependent manner. In another experiment DL-2-amino-5-phosphonovaleric acid (APV), a competitive antagonist of NMDA, was given ICV with NMDA (50 nmol/kg) in the presence of ethanol. APV (10 and 100 nmol/kg, ICV) significantly attenuated the response of NMDA to enhance the depressant action of ethanol. When bicuculline methiodide, an antagonist of GABA, was given ICV with NMDA (50 nmol/kg), bicuculline methiodide reduced the effect of NMDA to produce a second loss of the righting reflex (return to the LORR) in the presence of ethanol. When NMDA (100 nmol/kg, ICV) was injected in the absence of ethanol into mice, NMDA by itself did not produce a loss of the righting reflex. In this investigation, the results suggest that NMDA can augment ethanol-induced depression possibly through an interaction between glutamatergic and GABAergeric systems in the CNS.

The presence of cocaine and benzoylecgonine in rat cerebrospinal fluid after the intravenous administration of cocaine.

Cocaine hydrochloride, in doses of 0.5, 1.0, 2.0 and 4.0 mg/kg, iv, was administered to male Sprague-Dawley rats. Cerebrospinal fluid (CSF) was collected from the cisterna magna over a 20 min period and blood samples were obtained at 20 min after cocaine administration. In addition, blood samples for the 1 mg/kg dose of cocaine were collected at 2, 10, 20 and 30 min following drug injection. Gas chromatography/mass spectrometry was used for the analysis of cocaine and its metabolites in plasma and CSF. The disappearance of cocaine (1 mg/kg) from the plasma exhibited first order kinetics with a half-life of 18.11 +/- 3.22 min. Cocaine and benzoylecgonine were found in CSF and the concentrations of cocaine and benzoylecgonine increased in CSF as the doses of cocaine were increased. CSF flow rates were not altered by the iv administration of cocaine or benzoylecgonine. The CSF-to-plasma ratios for cocaine were quite similar to each other over the dosage range of cocaine that was administered; however, the CSF-to-plasma ratios for benzoylecgonine decreased as the concentrations of benzoylecgonine increased in plasma and CSF. When benzoylecgonine (2 mg/kg, iv) was given, the compound was detected in CSF indicating that benzoylecgonine can enter into the central nervous system from the peripheral blood. This investigation shows that cocaine and benzoylecgonine can be assayed in CSF and that the plasma levels of these compounds correlate with their concentrations in CSF.

The accumulation and disappearance of cocaine and benzoylecgonine in rat hair following prolonged administration of cocaine.

Hair samples were obtained at various time periods from male Sprague-Dawley rats following the injection of cocaine hydrochloride in doses of 5, 10, and 20 mg/kg, ip, for 28 days. Hair samples were also taken continually after the dosing was stopped until the presence of cocaine and benzoylecgonine were no longer detected in hair. Cocaine and benzoylecgonine in hair and plasma were analyzed by gas chromatography/mass spectrometry. Both cocaine and benzoylecgonine were found in hair samples 4 days after the initiation of cocaine administration. When cocaine dosing was stopped after 28 days, approximately 25 to 30 days were required for cocaine and benzoylecgonine to disappear from rat hair in the group of animals that received the highest dose of cocaine. The disappearance of cocaine and benzoylecgonine followed first-order kinetics. The mean rate constant and mean half-life for cocaine disappearance from hair were 0.212 +/- 0.005 day-1 and 3.31 +/- 0.09 days, respectively, and the mean rate constant and mean half-life for benzoylecgonine disappearance from hair were 0.098 +/- 0.006 day-1 and 6.90 +/- 0.28 days, respectively. The mean plasma concentrations of cocaine on Day 25 for the 5, 10, and 20 mg/kg doses of cocaine were 508 +/- 42, 852 +/- 95, and 2027 +/- 75 ng/mL, respectively, and the mean plasma benzoylecgonine levels for the 5, 10, and 20 mg/kg doses of cocaine were 49.9 +/- 7.0, 103.3 +/- 9.3, and 191.0 +/- 16.0 ng/mL, respectively. There was a positive correlation between the doses of cocaine hydrochloride administered and the plasma levels of both cocaine and benzoylecgonine. This study showed that cocaine and benzoylecgonine can be measured in rat hair following the administration of cocaine and that it was possible to correlate the concentrations of cocaine and benzoylecgonine found in hair with the doses of cocaine that were administered.

Cysteine sulfinic acid can enhance the central depressant effect of ethanol in mice.

The interaction between ethanol and cysteine sulfinic acid was examined in male Swiss-Webster mice. The loss of the righting reflex (LORR) was used as a measurement of central nervous system depression. In addition, the interaction between ethanol and cysteic acid, a metabolite of cysteine sulfinic acid, was studied. Immediately after the animals regained the righting reflex following ethanol injection (IP), mice were given an ICV injection of saline, cysteine sulfinic acid (1, 15 or 25 mumol/kg) or cysteic acid (1, 15, or 25 mumol/kg). There occurred a return to the LORR within 30 s after the ICV injection of drugs. The return to the LORR by the administration of the amino acids in the presence of ethanol occurred in a dose-dependent fashion. When cysteine sulfinic acid or cysteic acid (25 mumol/kg, ICV) was injected in the absence of ethanol, no loss of the righting reflex occurred. In other experiments, bicuculline methiodide was given ICV with cysteine sulfinic acid (25 mumol/kg), cysteic acid (25 mumol/kg), or GABA (25 mumol/kg) in the presence of ethanol. Bicuculline methiodide, a GABA antagonist, reduced the effects of the three amino acids to produce a return to the LORR in the presence of ethanol. These results indicate that cysteine sulfinic acid, an excitatory amino acid, and cysteic acid can enhance the central depressant properties of ethanol. Since bicuculline antagonized the effects of these two amino acids, a GABAergic mechanism may be involved in the interaction between ethanol and cysteine sulfinic acid or cysteic acid.

The interaction between ethanol and cysteine on the central depressant effects of ethanol in mice.

In this study male Swiss-Webster mice were used to examine the effects of cysteine (ICV), a precursor in the biosynthesis of taurine, on ethanol-induced loss of the righting reflex. The interaction of ethanol with gamma-aminobutyric acid (GABA) and isethionic acid, a metabolite of taurine, was also investigated on ethanol-induced central nervous system depression as measured by loss of the righting reflex experiments. Immediately after the animals regained the righting reflex following ethanol injection (IP) mice received an ICV injection of saline, cysteine (1, 15 or 25 mumol/kg), GABA (1, 15 or 25 mumol/kg) or isethionic acid (25 or 50 mumol/kg). Upon ICV administration of cysteine or GABA the mice again lost the righting reflex. This effect occurred immediately and in a dose-dependent manner. The compound, isethionic acid, failed to cause a second loss of the righting reflex following ethanol administration (IP). In the absence of ethanol cysteine or GABA (25 mumol/kg, ICV) did not produce a substantial loss of the righting reflex in mice. In another experiment mice were pretreated (IP) with L-2-oxothiazolide-4-carboxylate (OTC) 2 hr prior to ethanol administration (IP). OTC is a compound which can be converted to cysteine in the body. In the presence of ethanol OTC (15 mmol/kg) caused an enhancement of ethanol-induced central nervous system depression under certain conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of taurine on ethanol-induced sleep time in mice genetically bred for differences in ethanol sensitivity.

Long Sleep (LS) and Short Sleep (SS) mice were used in this study to investigate the interaction between ethanol and taurine. Sleep time (hypnosis) was selected as an index of ethanol-induced central nervous system depression. In order to achieve a similar degree of central nervous system depression with ethanol, SS and LS mice received 5.3 and 3.0 g/kg, IP, of ethanol, respectively. When taurine (7.5, 15 and 25 mumol/kg) was administered intracerebroventricularly (ICV) to LS and SS mice immediately after regaining the righting reflex following ethanol injection, a return to sleep time was produced. This effect of taurine was immediate in onset and occurred in a dose-dependent fashion. LS mice exhibited a greater effect from taurine administration than SS mice. In another experiment LS and SS mice were given ICV TAG, a taurine antagonist (6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide HCl), which significantly reduced the effect of taurine to produce a return to sleep time in the presence of ethanol. TAG did not affect ethanol-induced sleep time. In control experiments, in the absence of ethanol, neither taurine (25 mumol/kg, ICV) nor TAG (1 mumol/kg, ICV) caused a significant loss of the righting reflex (sleep time). When pentobarbital (50 mg/kg, IP) was injected instead of ethanol in the sleep time experiments, taurine (7.5, 15 and 25 mumol/kg, ICV) produced a return to sleep time in LS and SS mice that resembled the effect of taurine with ethanol in SS mice. These results indicate that taurine (ICV) can enhance the central depressant action of ethanol and pentobarbital and that the greatest effect of taurine occurred with LS mice in the presence of ethanol. It is possible that taurine may have some role in the central nervous system depressant properties of ethanol.

Effect of muscimol on ethanol-induced central nervous system depression.

In male Sprague-Dawley rats acute ethanol (1.0 and 2.0 g/kg) produced impairment of motor coordination and induced hypnosis (4.0 g/kg). Muscimol (1.25 mg/kg, IP) prior to ethanol administration enhanced motor impairment as measured by the aerial righting reflex. The rate of ethanol disappearance from the blood was unaltered by muscimol. Functional tolerance to the effect of ethanol on sleep time was produced by a 24 hr ethanol inhalation procedure. Animals tested 48 hr after ethanol inhalation exhibited a reduced sleep time from ethanol (4.0 g/kg). Muscimol (1.75 mg/kg) was administered along with ethanol 48 hr following 1 day of ethanol inhalation. Although the animals exhibited tolerance to ethanol-induced hypnosis, they did not manifest tolerance to the effect of muscimol.

Ethanol-induced sleep time: interaction with taurine and a taurine antagonist.

In male Swiss-Webster mice sleep time (hypnosis) was used as an index of ethanol-induced central nervous system depression. Ethanol (4 g/kg, IP) was administered to animals and the onset to sleep time (loss of the righting reflex) and the duration of sleep time were recorded. At the end of the ethanol-induced sleep time, taurine (7.5, 15 or 25 mumol/kg, ICV) was injected. Immediately after the ICV injection of taurine the mice again lost the righting reflex. This effect of taurine occurred in a dose-dependent fashion. In the absence of ethanol, taurine (25 mumol/kg, ICV) did not produce a significant sleep time. In another experiment when TAG, 6-amino-methyl-3-4H-1,3,4-benzothiadiazine-1,1-dioxide HCl, (a taurine antagonist) was given to mice, TAG (0.9 mumol/kg, ICV) significantly reduced the effect of taurine (7.5, 15 and 25 mumol/kg, ICV) to reinstate a sleep time in the presence of ethanol. TAG, however, did not alter ethanol-induced sleep time. These results indicate that taurine (ICV) can enhance the central depressant action of ethanol and that this effect of taurine can be attenuated by TAG. The antagonism of taurine by TAG appears to be noncompetitive in nature.

Effects of L-ascorbic acid on ethanol-induced central nervous system depression in mice.

Male Swiss-Webster mice were administered ethanol immediately before a motor coordination test. Controls and animals treated with 1, 2 or 3 g/kg, IP, of ethanol remained on a suspended meter stick for 240 +/- 0, 232 +/- 8, 93 +/- 2 and 75 +/- 5 sec, respectively. Blood ethanol levels at the end of the test period (4 min) or when the animal fell from the meter stick were 1.02 +/- 0.03, 2.13 +/- 0.09 and 2.24 +/- 0.07 mg/ml for the 1, 2 and 3 g/kg dose of ethanol, respectively. Thirty min prior to ethanol (2 g/kg, IP) animals received L-ascorbic acid in doses of 500 or 1000 mg/kg, IP. Both doses of L-ascorbic acid significantly enhanced the duration of time that the animals spent on the meter stick. When animals were given 1 g/kg, IP, of ethanol their rate of walking (cm/min) on the meter stick was significantly increased over controls. Administration of L-ascorbic acid (1000 mg/kg, IP) 30 min prior to ethanol (1 g/kg) did not change the rate of locomotion. In experiments on ethanol-induced hypnosis (sleep-time), animals received L-ascorbic acid (250, 500, 1000 or 1500 mg/kg, IP) or saline 30 min prior to ethanol (4 g/kg, IP). L-ascorbic acid increased the time of onset of hypnosis significantly at doses of 1000 and 1500 mg/kg. With these doses of L-ascorbic acid sleep duration and blood ethanol content were not altered. L-ascorbic acid, however, increased ethanol-induced hypnosis at a dose of 500 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

An inhalation procedure to produce tolerance to the behavioral effects of ethanol.

In male Sprague-Dawley rats the acute effect of ethanol administration (1.0, 2.0, or 3.0 g/kg, IP) on motor coordination was measured by the aerial righting reflex. Ethanol in doses of 2.0 and 3.0 g/kg produced significant impairment of motor coordination with corresponding elevated blood ethanol levels. The rate of ethanol dissappearance from the blood was 0.32 +/- 0.03 mg/ml/hr. Functional tolerance to the effect of ethanol on motor coordination and hypnosis (sleep time) was produced in rats by a 24 hr period of exposure to ethanol vapor (28 mg/liter of air) in a chamber. Animals tested 48 hr after the ethanol inhalation period showed less motor impairment from acute ethanol (3.0 g/kg, IP) and other animals exhibited a reduced sleep time from ethanol (4.0 g/kg, IP) when they were compared with controls. The rate of ethanol elimination from the blood was unchanged in ethanol vapor treated animals (0.30 +/- 0.01 mg/ml/hr) and air-treated animals (0.33 +/- 0.02 mg/ml/hr).

Acute effects of taurine and a taurine antagonist on ethanol-induced central nervous system depression.

Sprague-Dawley rats received taurine intracerebroventricularly (i.c.v.) 30 min prior to ethanol (4 g/kg, i.p.). The duration of ethanol-induced sleep time was increased with taurine at doses of 7.5, 14.0 and 25.0 mumol/kg. In another experiment, TAG (a taurine antagonist, i.c.v.) was given 5 min prior to taurine (i.c.v.) and ethanol was administered 30 min later. TAG antagonized the effect of taurine to enhance ethanol-induced sleep time. These results suggest an interaction between taurine and the depressant effect of ethanol in the brain.

Sampling of orbital sinus blood closely reflects brain ethanol content in rats.

It was demonstrated that the aerial righting reflex can be used as an index of acute ethanol-induced impairment of motor coordination in rats, and was found to directly correlate with blood ethanol content from the infraorbital plexus. A study of ethanol within the blood and its distribution in brain regions showed that the ethanol content of orbital sinus blood closely reflected that in the cerebral cortex, midbrain, and cerebellum. Ethanol administration by intraperitoneal (IP) injection (2, 3 or 4 g/kg) produced the same distribution as 24 hr ethanol vapor inhalation (28 mg/l). Blood ethanol concentrations were slightly higher than brain ethanol concentrations when measured at 10, 30, and 60 min after IP injection and immediately following ethanol vapor administration. Also, in rats 48 hr following ethanol vapor inhalation when tolerance to ethanol is exhibited, the distribution and concentrations of ethanol in blood and brain from acute ethanol (2 g/kg, IP) were unaltered when compared with controls. These data suggest that ethanol distribution within the brain does not play a role in the phenomenon of tolerance to ethanol.