Effects of alpha-chloralose on the activity of the nigrostriatal dopaminergic system in the cat.
The effects of alpha-chloralose anaesthesia were studied in the cat on the release of 3H-dopamine (#H DA) from the caudate nucleus and the substantia nigra using the push-pull cannula method and continuous labelling of the structures with L-3,5-3H-tyrosine. Results were compared to those obtained under the same experimental conditions in both halothane-anaesthetized animals and 'encéphale isolé' preparations. The alpha-chloralose-anaesthetized preparation showed the lowest level of 3H-DA release, both from dopaminergic nerve terminals in the caudate nucleus and from dendrites of dopaminergic neurons in the substantia nigra. Furthermore, the time required to reach a steady-state release of 3H-DA was longer in alpha-chloralose-anaesthetized cats than in animals under halothane. This indicated that the activity of the dopaminergic neurons is depressed under alpha-chloralose anaesthesia. In the second part of the study, we measured the effects of unilateral somatic stimulation on the release of 3H-DA from the caudate nuclei and substantiae nigrae on both sides of the brain. The results show that under alpha-chloralose anaesthesia, the electric stimulation of the paw of the right forelimb does not significantly affect the release of 3H-DA from any of the above four structures. This contrasts with the changes of 3H-DA release seen in the same experimental conditions under halothane anaesthesia.
D000818:Animals; D002415:Cats; D002421:Caudate Nucleus / Q000378:metabolism; D002698:Chloralose / Q000494:pharmacology*; D003342:Corpus Striatum / Q000187:drug effects*; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D004558:Electric Stimulation; D009475:Neurons, Afferent / Q000502:physiology; D013378:Substantia Nigra / Q000187:drug effects* / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D002698:Chloralose; D014443:Tyrosine; D004298:Dopamine