Andrew P. Ferko

Induction of physical dependence in rats by ethanol inhalation without the use of pyrazole

Abstract Rats were exposed to increasing air ethanol concentrations (14 to 28 mg/liter) over a 10-day period without the use of pyrazole. There was a positive correlation between the rising air ethanol concentrations in the chamber and the concentrations of ethanol in the blood. On Day 10 the animals were removed from the chamber with a mean blood ethanol concentration of 3.13 mg/ml and observed for signs of withdrawal over a 24-hr period. During this time all animals manifested spontaneous signs of withdrawal and convulsions on handling. There was a positive correlation between the spontaneous signs and convulsions on handling. The disappearance of ethanol from the blood followed zero-order kinetics over the first 7 hr. In the withdrawal phase of the experiments a definite negative correlation existed between the decreasing blood ethanol concentrations and the rise in the scores for convulsions on handling. This inhalation procedure is a simple, reproducible approach for causing physical dependence on ethanol in rats without the use of pyrazole and with the maintenance of original body weight.

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)

Physical dependence on ethanol: Rate of ethanol clearance from the blood and effect of ethanol on body temperature in rats

Abstract An inhalation procedure for the administration of ethanol without the use of pyrazole was employed to produce physical dependence on ethanol in rats. A reduction in body temperature was noted at the latter part of the induction phase and in the early hours of withdrawal. In the withdrawal phase the animals experienced convulsions on handling and sponataneous signs of withdrawal. To investigate the rates of ethanol clearance from the blood po and ip routes of ethanol administration were used. A significant enhancement of the rate of ethanol disappearance from the blood was measured in the animals at 48 hr following 10 days of ethanol exposure. Also at this 48-hr time period the usual hypothermic response to ethanol administration was lost in these animals as compared to a control group and to animals receiving ethanol ip, at 7 days after exposure to ethanol vapor. The data indicated that the loss of hypothermic effect from ethanol might be a factor in the increased rate of ethanol clearance. However, in studying the rate of ethanol disappearance from the blood in nondependent animals at 34°C which prevented hypothermia, there was no difference in the rates of ethanol clearance as compared to controls at 23.5°C where the hypothermic effect from ethanol was present. It appears that body temperature does not play a role in the observed acceleration of ethanol clearance from the blood in animals which have undergone withdrawal.

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.

Rates of ethanol disappearance from blood and hypothermia following acute and prolonged ethanol inhalation

Abstract An inhalation procedure was employed for the acute and prolonged administration of ethanol. The rate of ethanol clearance from blood of rats following 6 hr of inhalation was significantly faster than the rates of clearance associated with the ip or po routes of administration. Also, the blood clearances from ip and po ethanol differed significantly. However, the rates of ethanol disappearance were constant for a given route, such as inhalation or ip, regardless of the dose administered. Immediately after 10 days of ethanol inhalation, the rate of ethanol elimination was not accelerated when compared to the results obtained for 6 and 24 hr of inhalation. When the animals were again treated for 6 hr with ethanol vapor 48 hr post-10-day exposure, a significant enhancement of the rate of ethanol disappearance from the blood was observed. In another experiment, utilizing a 24-hr period of ethanol exposure, it was possible 48 hr later to separatethe accelerated rate of ethanol clearance from blood and the concomitant loss of hypothermia, which previously had been observed to occur 48 hr after prolonged ethanol inhalation. In addition, the data suggested that an increased rate of ethanol clearance is not a contributory factor to the loss of hypothermia, when these two events occur concurrently. Therefore, it appears that functional tolerance rather than metabolic tolerance was observed. Finally, when various ip doses of ethanol were administered to naive rats, it was found that a minimal peak blood ethanol concentration of 1.48 mg/ml had to be attained to produce hypothermia.

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.

Lead and δ-aminolevulinic acid concentrations in human parotid saliva

Abstract Quantitative values of lead and δ-aminolevulinic acid in normal human parotid saliva were determined and were found to be 3.1 (±0.5) and 10.2 (±0.6) μg/100 ml, respectively. The relationship of salivary lead concentration to blood lead concentration was examined. For the experimental population studied, parotid saliva was estimated to contain approximately 13% of the blood lead concentration. No significant difference was found between parotid saliva and plasma δ-aminolevulinic acid concentrations.

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.

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.