Behavioral analysis of PTZ-kindled rats after acute and chronic ethanol treatments

Clavulanic acid improves ethanol withdrawal symptoms in rats

Objective(s):

Ethanol withdrawal following chronic use, is an important challenge clinically. In this study, the effect of clavulanic acid was evaluated on the symptoms of ethanol withdrawal in rats.

Materials and Methods:

Alcohol dependence was induced by the gavage of ethanol (10% v/v, 2 g/kg), twice daily for 10 days. Clavulanic acid (10, 20, 40, and 80 mg/kg) was administered concurrently with ethanol (sub-acute study), or a single dose after ethanol withdrawal (acute study). Six hours after the last dose of ethanol, anxiety was assessed by the elevated plus-maze (EPM). Seizure-like behavior was evaluated by a sub-convulsive dose of pentylenetetrazol (PTZ, 25 mg/kg/IP). Locomotor activity and motor coordination were measured by the open field and rotarod tests, respectively. Lipid peroxidation marker and antioxidant content were assessed through measuring malondialdehyde (MDA) and glutathione (GSH), respectively.

Results:

The number of entries and time spent on the open arms of EPM decreased during the withdrawal state. Motor coordination and locomotor activity were significantly decreased. In the sub-acute study, clavulanic acid 80 mg/kg increased time spent and the number of entries to the open arms of EPM, in withdrawn animals. Both motor incoordination and locomotor activity reduction were normalized by clavulanic acid (10, 20, 40 and 80 mg/kg). Withdrawal-induced PTZ kindling seizure was also suppressed by all of the doses. MDA increased, while GSH decreased after withdrawal. Clavulanic acid attenuated such changes.

Conclusion:

Clavulanic acid could prevent the development of alcohol withdrawal-induced anxiety and seizure. Alcohol withdrawal causes oxidative stress which can be prevented by clavulanic acid.

The role of GABA(A) receptors in the acute and chronic effects of ethanol: a decade of progress

The past decade has brought many advances in our understanding of GABA(A) receptor-mediated ethanol action in the central nervous system. We now know that specific GABA(A) receptor subtypes are sensitive to ethanol at doses attained during social drinking while other subtypes respond to ethanol at doses attained by severe intoxication. Furthermore, ethanol increases GABAergic neurotransmission through indirect effects, including the elevation of endogenous GABAergic neuroactive steroids, presynaptic release of GABA, and dephosphorylation of GABA(A) receptors promoting increases in GABA sensitivity. Ethanol's effects on intracellular signaling also influence GABAergic transmission in multiple ways that vary across brain regions and cell types. The effects of chronic ethanol administration are influenced by adaptations in GABA(A) receptor function, expression, trafficking, and subcellular localization that contribute to ethanol tolerance, dependence, and withdrawal hyperexcitability. Adolescents exhibit altered sensitivity to ethanol actions, the tendency for higher drinking and longer lasting GABAergic adaptations to chronic ethanol administration. The elucidation of the mechanisms that underlie adaptations to ethanol exposure are leading to a better understanding of the regulation of inhibitory transmission and new targets for therapies to support recovery from ethanol withdrawal and alcoholism.

Effects of Intrahippocampal Nicotine and Neurosteroid Administration on Withdrawal in Voluntary and Chronic Alcohol-Drinking Rats

BACKGROUND

Previous studies have shown that 4.6 mug of nicotine administered to the hippocampus can deteriorate learning acquisition in alcohol-drinking rats. The aim of the present study was to research whether this nicotine dose can alter the alcohol withdrawal syndrome and whether the two neurosteroids, allopregnanolone (AlloP) and pregnenolone sulfate (PregS), at doses previously reported as anxiolytic and promnesic, respectively, can modulate these effects.

METHODS

We used a free-choice drinking procedure that involved providing the rats with an alcoholic solution (10% ethanol) at an early age. Alcohol and control rats were assigned randomly to six groups that received two consecutive intrahippocampal (dorsal CA1) injections once per week during three consecutive weeks after one hour of ethanol drinking. The first injection was nicotine (4.6 microg, 20 mM) or saline and the second injection was PregS (5 ng, 24 microM), AlloP (0.2 microg, 1.26 microM) or saline. Blood alcohol concentrations were assessed one week before the withdrawal testing. Locomotor activity and audiogenic seizures were tested during withdrawal after 110 days of voluntary ethanol consumption. Rats were injected immediately before the withdrawal testing.

RESULTS

AlloP induced a decrease in horizontal and vertical activities, suggesting that the dose tested has sedative effects. AlloP reversed the seizures induced by ethanol withdrawal and also the spontaneous audiogenic seizures induced by the acoustic stimulation in control rats. Moreover, AlloP decreased other alcohol withdrawal signs, such as tail stiffening and body rigidity. Intrahippocampal administration of nicotine or PregS, at the doses tested, did not effectively modify the expression of audiogenic seizures induced by alcohol withdrawal.

CONCLUSIONS

These results show that hippocampal GABAergic activity and AlloP have an important role in preventing convulsive behavior. The results also highlight the therapeutic potential of AlloP for reducing the alcohol withdrawal syndrome.