Elsevier

Neuroscience

Volume 85, Issue 3, 24 April 1998, Pages 919-930
Neuroscience

Rat striatal adenosinergic modulation of ethanol-induced motor impairment: possible role of striatal cyclic AMP

https://doi.org/10.1016/S0306-4522(97)00627-1Get rights and content

Abstract

We have previously reported the involvement of the striatum in acute ethanol-induced motor incoordination and the striatal adenosinergic modulation of ethanol-induced motor incoordination through A1 receptor-mediated mechanism(s). The present study, a continuation of our previous work, was carried out to investigate the possible functional correlation between striatal cyclic AMP and ethanol-induced motor incoordination, and its modulation by striatal adenosine in Sprague–Dawley rats. Forskolin (0.1, 0.5 and 1.0 pmol), a known activator of adenylate cyclase, significantly attenuated ethanol-induced motor incoordination in a dose-dependent manner following its direct intrastriatal microinfusion. Forskolin also antagonized the accentuating effect of intrastriatal N6-cyclohexyladenosine on ethanol-induced motor incoordination. These results suggested that ethanol-induced motor incoordination might be functionally correlated to a decrease in the striatal cyclic AMP levels and that the striatal adenosine A1 receptors might modulate ethanol-induced motor incoordination through cyclic AMP signaling mechanism(s). Further support to this hypothesis was obtained by the actual measurement of the striatal cyclic AMP levels in the same experimental conditions as in motor coordination studies using high-performance liquid chromatography with fluoroscence detection. Regardless of the method (focused microwave irradiation, cervical dislocation or decapitation into a dry ice–ethanol mixture) used to kill the animals, a significant decrease in the striatal cyclic AMP levels was observed due to ethanol. Intrastriatal adenosine A1-selective agonist, N6-cyclohexyladenosine (24 ng), caused a further significant decrease in the striatal cyclic AMP levels in the ethanol- but not in the vehicle-treated animals. The further enhancement in the ethanol-induced decrease in the striatal cyclic AMP levels by intrastriatal N6-cyclohexyladenosine, therefore, functionally correlated with the observed potentiating effect of intrastriatal N6-cyclohexyladenosine on ethanol-induced motor incoordination. The effects of intrastriatal N6-cyclohexyladenosine+ethanol and of ethanol alone on the striatal cyclic AMP levels were blocked by intrastriatal pertussis toxin (500 ng) pretreatment, indicating the involvement of pertussis toxin-sensitive G-proteins (Gi, Go) and possibly of the adenosine A1 receptor coupled to the G-proteins in the striatum. Furthermore, ethanol alone significantly decreased the basal as well as the cyclic AMP-stimulated catalytic activities of the striatal cyclic AMP protein kinase, which were further reduced by intrastriatal N6-cyclohexyladenosine.

The results of the present study therefore support an involvement of a cyclic AMP signaling pathway in the striatal adenosinergic modulation of ethanol-induced motor incoordination at the post-adenosine A1 receptor level.

Section snippets

Animals

Male Sprague–Dawley rats (Charles River, Raleigh, NC, U.S.A.), weighing 150–200 g, were used in the entire study. Following their arrival, the rats were housed individually in polyethylene cages with free access to food and water in a temperature- (24±1°C) and humidity-controlled room. The animals were exposed to a 12-h light/12-h dark day–night cycle, with lights on at 7.00 a.m. All efforts were made to minimize animal suffering, to reduce the number of animals used and to utilize alternatives

Results

As reported previously,28, 291.5 g/kg was the test dose of ethanol used throughout the present investigation. The selection of the test dose was based on a separate dose–response study (data not shown). The test dose of ethanol produced significant motor incoordination with little or no observable sedation. The onset of motor incoordination was rapid and usually reached the maximal level within 15–20 min post-ethanol, followed by the gradual recovery of up to 90% of the normal motor coordination

Discussion

In the present investigation, the intrastriatal microinfusion of the adenosine receptor agonist, CHA, significantly accentuated the motor incoordinating effect of ethanol. The adenosine agonist, however, did not alter the normal motor coordination in the absence of ethanol. This effect of adenosine agonist on EIMI was achieved mainly through the activation of striatal adenosine A1 receptors and was antagonized by the A1 antagonist, DPCPX, as already explained in the Introduction.14, 17, 28, 29

Conclusions

In summary, the results from the present study suggest the involvement of striatal cAMP in the actions of ethanol and its modulation by striatal adenosine. The results of the present and previous investigations28, 29support a significant functional interaction between the striatal adenosinergic system and ethanol. Striatal adenosine and/or adenosine A1 receptors might modulate EIMI through (a) cAMP–PKA-mediated mechanism(s).

Acknowledgements

The authors are grateful to Ms Pam Wynne for her excellent word processing in the preparation of this manuscript.

References (55)

  • J Krupinski et al.

    Molecular diversity in the adenylyl cyclase family. Evidence for eight forms of the enzyme and cloning of type VI

    J. biol. Chem.

    (1992)
  • L.E Nagy

    Role of adenosine A1-receptor in inhibition of receptor-stimulated cyclic AMP production by ethanol in hepatocytes

    Biochem. Pharmac.

    (1994)
  • L.E Nagy et al.

    Ethanol increases extracellular adenosine by inhibiting adenosine uptake via nucleoside transporter

    J. biol. Chem.

    (1990)
  • P Pisano et al.

    Activation of the adenylate cyclase-dependent protein kinase pathway increases high affinity glutamate uptake into rat striatal synaptosomes

    Neuropharmacology

    (1996)
  • C.S Rabe et al.

    Effect of ethanol on cyclic AMP levels in intact PC12 cells

    Biochem. Pharmac.

    (1990)
  • J.D Redos et al.

    Lack of alteration in regional brain adenosine-3′,5′-cyclic monophosphate levels after acute and chronic treatment with ethanol

    Life Sci.

    (1976)
  • J.A Ribeiro et al.

    Adenosine receptors and calcium: basis for proposing a third (A3) adenosine receptor

    Prog. Neurobiol.

    (1986)
  • R Rius et al.

    Cyclic AMP-dependent protein phosphorylation is reduced in rat striatum after chronic ethanol treatment

    Brain Res.

    (1986)
  • N.F Rossi et al.

    Pertussis toxin reverses adenosine receptor-mediated inhibition of renin secretion in rat renal cortical slices

    Life Sci.

    (1987)
  • Q.H Shi et al.

    Forms of adenylate cyclase, activation and/or potentiation by forskolin

    Archs Biochem. Biophys.

    (1986)
  • M Sinensky et al.

    Increased membrane acyl chain ordering activates adenylate cyclase

    J. biol. Chem.

    (1979)
  • C.P Smith et al.

    Cyclic AMP-dependent protein kinase activity in the brains of alcohol-preferring (P) and nonpreferring (NP) rats

    Alcohol

    (1991)
  • P.K Smith et al.

    Measurement of protein using bicinchoninic acid

    Analyt. Biochem.

    (1985)
  • M Sugawa et al.

    Age-related alteration in signal transduction: involvement of the cAMP cascade

    Brain Res.

    (1993)
  • K Beeker et al.

    Ethanol-induced growth inhibition in embryonic chick brain is associated with changes in cytoplasmic cyclic AMP- dependent protein kinase regulatory subunit

    Alcohol and Alcoholism

    (1988)
  • M Bohm et al.

    Pertussis toxin prevents adenosine receptor- and m-cholinoceptor-mediated sinus rate slowing and AV conduction block in guinea-pig heart

    Naunyn-Schmiedeberg's Arch. Pharmac.

    (1989)
  • Bonnichsen R. (1965) Ethanol-determination with alcohol dehydrogenase and DPN. In Methods of Enzymatic Analysis (ed....
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    Present address: Upjohn Pharmaceutical Company, CNS Research Unit 7251-209-506, Kalamazoo, MI 49001, U.S.A.

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