Carlton K. Erickson

Effects of acute and chronic ethanol administration on whole mouse brain synaptosomal calcium influx

Abstract Whole brain synaptosomes, isolated from pair-fed acute in vitro (sucrose-Sustacal diet for 10 days), acute in vivo [4.5g/kg, 20% (w/v) i.p. ethanol pretreatment] and chronic in vivo (ethanol-Sustacal diet for 10 days) female, Swiss-Webster mice, were challenged in vitro with ethanol (80 mM, final concentration) in either an incubation medium (12-min exposure), a depolarizing medium (2-min exposure with 74 mM KCI) or a nondepolarizing medium (2-min exposure with 5 mM KCl). Depolarizing and nondepolarizing media also contained 45 Ca 2+ (2μCi/μmole). The results showed (1) a significant enhancement of 45 Ca 2+ influx when synaptosomes isolated from acute in vitro and acute in vivo mice groups were challenged in vitro by ethanol (80 mM) in the depolarizing medium (74 mM KCl), (2) a significant enhancement by 80 mM ethanol of 45 Ca 2+ accumulation by nondepolarized synaptosomes isolated from the acute in vitro mouse group, (3) a significant increase in 45 Ca 2+ accumulation in synaptosomes from acute in vivo mice as compared with acute in vitro mice without an in vitro ethanol challenge, and (4) a significant decrease in 45 Ca 2+ accumulation by synaptosomes isolated from chronic in vivo mice as compared to acute in vitro synaptosomes. The results presented here demonstrate the ability of ethanol to significantly increase calcium accumulation into whole brain synaptosomes and that tolerance to this phenomenon occurs in parallel with behavioral tolerance to the sedative action of ethanol. These ethanol-induced changes in calcium accumulation may be involved in the production of sedation and tolerance to sedation.

Alteration of ethanol-induced changes in locomotor activity by adrenergic blockers in mice.

The effects of various doses of ethanol (ETOH) on spontaneous locomotor activity (SLMA) in mice were measured using photocell activity chambers. Of the 4 i.p. doses injected, the 2 lowest doses (0.5 and 1.0 g/kg) stimulated SLMA, the next higher dose (2.0 g/kg) produced a biphasic effect of depression followed by stimulation, and the highest dose (4.0 g/kg) depressed SLMA. The mechanism of the biphasic effect of the 2.0 g/kg dose was studied in tests with central catecholamine antagonists at various doses 30 min before ETOH. Doses of 5, 10, and 20 mg/kg of propranolol, a β-receptor blocker, significantly antagonized the depressant effect of ETOH but had no influence on the stimulant effect. High doses (10 and 20 mg/kg) of phentolamine, an α-receptor blocker, significantly antagonized the stimulant phase of ETOH action but had no significant effect on the depressant phase. All doses (0.062–0.250 mg/kg) of spiroperidol, a dopaminergic blocking drug, significantly enhanced the SLMA depression produced by ETOH. These results indicate that the SLMA-depressant effect of ETOH may be mediated by central “beta-type” receptors, that the SLMA-stimulant effect of ETOH may be mediated by central “alpha-type” receptors, and that at least part of ETOHs action may be due to dopaminergic mechanisms.

Studies on the mechanism of avoidance facilitation by nicotine

A series of experiments were conducted to determine whether nicotine facilitates avoidance acquisition by enhancing consolidation or merely by stimulating performance. Sprague-Dawley albino rats were trained for 15 one-hour sessions in a discriminated leverpress avoidance situation with buzzer as a conditioned stimulus. More rats receiving nicotine, 0.4 mg/kg, i.p. immediately before each one-hour daily session (presession) reached a preset learning criterion than did saline controls, and rats receiving 0.1 mg/kg of nicotine performed better than controls but not as well as those receiving the higher nicotine dose. Rats given similar doses of quaternary nicotine bismethiodide in an identical presession experiment did not learn more proficiently than controls. Other groups of rats were given four doses of nicotine in photocell activity cages and the doses of nicotine which facilitated avoidance acquisition actually depressed spontaneous motor activity. Later studies in which rats were given 0.1 and 0.4 mg/kg nicotine or saline i.p. immediately after each session (postsession) showed that the drug also facilitates avoidance acquisition by this method; however, only the lower dose produced significant facilitation in this instance. Finally, rats were again trained with precession nicotine, but saline was substituted for nicotine beginning on session 16. No drug dissociation effect was seen. Thus the results of these studies strongly suggest that small doses of nicotine permanently facilitate the consolidating neural memory trace and do not enhance avoidance acquisition merely by stimulating performance.

Intoxication Is Not Always Visible: An Unrecognized Prevention Challenge

T HE USE OF alcohol or other drugs (AOD) to alter consciousness and produce intoxication is not new. Alcohol, for example, is the most widely used and abused drug on earth and has been consumed for its intoxicating effects for thousands of years. One consequence of AOD intoxication is impaired driving. One of the challenges facing prevention specialists is that many factors contribute to intoxication as well as to whether a person is ‘‘visibly intoxicated.’’ ‘‘Visible intoxication’’ (meaning a series of perceptible acts and behaviors consistent with gross impairment) is, in some cases, different from ‘‘obvious intoxication,’’ a term used in some state statutes (and some older studies to mean visibly intoxicated), that relates to a combination of all the factors used to determine whether a person is or is likely to be alcohol impaired. ‘‘Intoxication’’ is not always visible even to trained observers. The goals of this review are (i) to educate prevention specialists about the state of knowledge in determining intoxication, (ii) to provide an authoritative treatise on the subject of visible intoxication, and (iii) to address the medicolegal consequences of such intoxication—primarily the prevention of impaired driving. Historically, most of the direct consequences of intoxication have been limited to individual drinkers who, if they lived long enough, would eventually incur significant medical consequences (Brick, 2008). However, the introduction of motor vehicles and the eventual proliferation of mechanized transportation dramatically changed society. No longer were the effects of alcohol overuse limited to the drinker, but now others (passengers, occupants of other vehicles, and pedestrians) were included as well. Today about 14,000 alcohol-related fatal crashes occur per year (Yi et al., 2006). The actual number of crashes directly due to intoxication is probably lower as most recent epidemiological studies of this type include drivers with blood alcohol concentrations (BACs) of more than zero, and statistical methods, such as intupation, assume intoxication based on driver and crash profiles. But even when objective blood alcohol evidence is missing (US Department of Transportation ⁄National Highway Traffic Safety Administration, 2002), drunken driving is a major health hazard. Diverse approaches have been applied to prevent drunken driving (Hingson et al., 1996a,b, 1999; Holder et al., 2000; NIAAA, 2000) but only three approaches specifically relate to identifying signs of alcohol intoxication: DWI laws, dramshop ⁄ related host liability, and Alcohol Beverage Control Board laws. A review of differences between DWI-related issues and visible intoxication (the focus of dram shop laws) is important to the general public’s awareness and understanding of this problem, and the reduction of motor vehicle and other injuries due to intoxication. In this article, we review the development, scientific foundation, implications, and interrelationships among these approaches.

Correlation of Brain Amine Changes with Ethanol-Induced Sleep-Time in Mice

Earlier studies in our laboratories (Erickson and Graham, 1973; Graham and Erickson, 1974) have pointed out our interest in correlating central amine changes with certain aspects of ethanol intoxication. In the earlier studies we saw changes in acetylcholine (ACh) release from the cerebral cortex and reticular formation after various intravenous doses of ethanol in rabbits. Available literature concerning the effects of ethanol on catecholand indolealkylamines is voluminous, but incomplete and sometimes conflicting. For example, ethanol has been reported to deplete serotonin (5HT) and norepinephrine (NE) in the brain stem of rabbits (Gursey and Olson, 1960), and to raise brain 5HT of rats (Bonnycastle et al., 1962). Many workers, such as Haggendal and Lindqvist (1961), however, have seen no effect of ethanol on cerebral NE, DA or 5HT in rats or rabbits. Wallgren and Barry (1970) have concluded that, in general, ethanol appears to change brain levels of catecholamines and 5HT little, if at all. With regard to the effects of ethanol on the central amine ACh, Kalant et al. (1967) have seen decreased release of ACh in rat cortical slices in vitro while we have seen a short-lived increase in total brain ACh after ethanol in rats (Erickson and Graham, 1973).

Regional distribution of ethanol in rat brain

Abstract The cerebral distribution of a low ip dose of ethanol (ETOH) was studied using a double-barrelled, membrane-tipped perfusion cannula in rats. The cannulas were perfused with physiological solution in freely-moving animals at a rate of 19 μl/min for 5 min at 5, 10, and 15 min and subsequently at 15 min intervals for the remainder of 2 hrs after 1 g/kg ETOH. Peak blood ETOH levels (in mg/ 100 ml) after the single dose were 4 times those found in the lateral ventricle, 6–7 times those found in the reticular formation, cerebral cortex, and amygdala, and 9–11 times those found in the caudate and lateral hypothalamus. Peak levels were reached earliest in the lateral ventricle and reticular formation. In a related study, homogenized (“whole”) brain ETOH levels were found to be similar to blood levels while flushed (“bloodless”) brain ETOH levels were approximately 20% lower than those found in blood and “whole” brain. It is concluded that there is a significant differential distribution of ETOH in the rat brain after a low dose of ETOH, and that this unequal brain ETOH distribution may influence the behavioral effects of the drug.

Reviews: Drug Abuse and Dependency: Understanding Gender Differences in Etiology and Management

Objective To review the etiology, consequences, and treatment needs of drug abuse and dependency, especially in women. Data Sources Original studies and literature reviews published primarily since 1990. Data Synthesis Many studies, conducted mostly during the past 10 years, are providing new information regarding the genesis of two separate drug problems: willful abuse (misuse) of drugs and pathological drug dependency. Recent studies have also highlighted important differences between the sexes in the causes, consequences, and management of drug abuse and dependency. The neurobiologic and genetic contributions to the pathological disease of addiction provide important directions for future treatments, as a supplement to existing self-help and structured behavioral therapies. Pharmacotherapy also has an important role in reducing drug craving and relapse in addicted patients. Conclusion Although the precise causes of drug abuse and dependency continue to challenge researchers, important differences have been identified between men and women in terms of how drug use begins, how it progresses, and effective methods of treatment. Pharmacists and other health care professionals need to understand gender differences in the etiology and management of drug abuse and dependency and develop the capacity to recognize and refer women who may be abusing or dependent on drugs.

Ethanol dependence produced in rats by nutritionally complete diets

Nutritionally complete diets formulated according to American Institute of Nutrition guidelines were used to make rats dependent upon ethanol. When intubated with a diet-ethanol solution for four days maintained initial body weight. When forced to consume the solution as the sole source of nutrients and water for nineteen days, rats gained weight. All animals developed severe withdrawal signs as measured by the intensity of tremors and spastic rigidity. The diet ingredients did not alter the absorption of the ethanol. The results demonstrate that physical dependence on ethanol can be induced in the rat without nutritional impairment.

Calcium enhancement of alcohol and drug-induced sleeping time in mice and rats.

Calcium injected intracerebroventricularly (IVT) at various times before a hypnotic dose of ethanol significantly enhanced the duration of sleeping time (loss of righting reflex, LRR) in mice and rats. This cation also enhanced the duration of LRR induced by t-butanol and chloral hydrate, but not that induced by sodium pentobarbital. Other cations injected IVT (manganese, cadmium, and zinc) also enhanced ethanol-induced LRR. The synergistic effects of the ionophores X537A and A23187 on calcium-enhanced LRR, and the antagonism of ethanol-induced LRR by EDTA and EGTA suggest the involvement of a membrane-associated calcium pool in the hypnotic effect of ethanol. These studies show the generality of cation enhancement of alcohol-induced sleeping time in mice and rats, and confirm earlier reports which suggested that calcium is involved with the central nervous system depressant effects of alcohols.

Comparison of high-performance liquid chromatography electrochemical detectors for the determination of aporphines, catecholamines and melatonin

Abstract A Bioanalytical Systems detector showed a greater sensitivity for low-level determinations of apomorphine, norepinephrine, epinephrine, dopamine, and melatonin compared to a Brinkmann Instruments system. Modifications of the Bioanalytical Systems flow cell, which have been developed in our laboratories, increase the sensitivity toward certain catecholic compounds, generally decrease baseline noise, and allow for serial coupling of detectors. 2