Electrophysiological responses to ethanol, pentobarbital, and nicotine in mice genetically selected for differential sensitivity to ethanol.

Abstract

Cortical electroencephalographic (EEC) changes induced by ethanol (4.3 and 1.4 g/kg, ip), pentobarbital (50 and 16 mg/kg), and nicotine (1.0 g/kg) were examined in long-sleep (LS) and short-sleep (SS) mice that were genetically selected for differential sleep times induced by a hypnotic dosage of ethanol. Ethanol (4.3 g/kg) caused EEG changes that paralleled the behavioral differences, whereas no differences between selected lines were observed following the activating dose (1.4 g/kg). Data support the notion that the known difference in ethanol sleep times is due not to greater SS sensitivity to ethanol activation but rather to greater LS sensitivity to ethanol hypnosis. No differences between selected lines were observed following 50 mg/kg pentobarbital, which again parallels previous behavioral data. The SS mice were more responsive to pentobarbital activation (16 mg/kg). Nicotine more severely reduced EEG power and heart rate in LS mice; a continuous iv infusion of nicotine elicited a distinct pattern of behavioral stereotypy for each selected line, with more profound motor and reflex depression in LS mice. The lines do not differ in rate of nicotine metabolism, hence they must differ in central nervous system sensitivity to nicotine. Thus, lines of mice selectively bred for differential sensitivity to ethanol also display marked differences in electrophysiological and behavioral responses to nicotine.

Electrophysiological Effects of Allopregnanolone in Rats With a History of Ethanol Exposure

“…This is the first report of ALLO-induced changes in the hippocampal EEG. These ALLO-induced EEG changes mimic the patterns induced by benzodiazepines and barbiturates but not EtOH (Gandolfo et al, 1994;Robledo et al, 1994;Ryan et al, 1979;Slawecki et al, 2000b). In this light, these data continue to support the hypothesis that the mechanisms that mediate ALLO's EEG effects are closely related to those that mediate the EEG effects of benzodiazepines and barbiturates.…”

“…Macroelectrophysiological recording procedures [electroencephalograms (EEGs) and event-related potentials (ERPs)] also indicate that sedative-hypnotics have differing electrophysiological effects. Benzodiazepines, barbiturates, and ALLO increase high frequency (Ͼ10 Hz) EEG power (Gandolfo et al, 1994;Lancel et al, 1997;Leung, 1985;Robledo et al, 1994;Ryan et al, 1979;Slawecki et al, 2000b), but EtOH decreases high-frequency spectral power (Ehlers et al, 1992;Morzorati et al, 1988;Slawecki et al, 2000b). These differences may be attributed to factors that include actions at distinct sites on the GABA-A receptor, differential activity based on receptor subunit composition, and the regional distribution of receptor subtypes.…”

Low-dose ethanol produces mixed effects on cortico-hippocampal theta rhythms and modifies hippocampal theta frequency through multiple mechanisms

“…At higher (>1 g/kg) doses, a general ‘slowing’ of oscillations in the form of increased lower frequency (< 4 Hz) power coupled with a decrease in higher (5-15 Hz) frequency power is often described for the neocortex. For example, in mouse equivalents of Cg and RS in our study, 1.4 g/kg EtOH reduced the power and frequency of oscillations between 0-25 Hz (Ryan et al, 1979). Likewise, 0.8 g/kg in rabbits increased slower (.5-4 Hz) oscillation power at the expense of 5-15 Hz activities in the PFC (Czarnecka and Pietrzak, 1996).…”

Effects of Allopregnanolone on the EEG of Alcohol-Preferring and Alcohol-Nonpreferring Rats

“…These effects resemble those of barbiturates and benzodiazepines (Gevins et al, 1988;Lancel et al, 1994;Leung, 1985;Mandema et al, 1992;Robledo et al, 1994;Ryan et al, 1979;Urata et al, 1996) more than ethanol (Ehlers et al, , 1992bMarrosu et al, 1989;Ryan et al, 1979;Slawecki et al, 2000). These effects resemble those of barbiturates and benzodiazepines (Gevins et al, 1988;Lancel et al, 1994;Leung, 1985;Mandema et al, 1992;Robledo et al, 1994;Ryan et al, 1979;Urata et al, 1996) more than ethanol (Ehlers et al, , 1992bMarrosu et al, 1989;Ryan et al, 1979;Slawecki et al, 2000).…”