title: Effect of increasing doses of intracaudate haloperidol upon motor expressions that require an intact substantia nigra pars reticulata and/or superior colliculus in cats.
abstract: In the present study it was investigated whether intracaudate (CN) injections of increasing doses of haloperidol progressively affect movements that require the integrity of the substantia nigra pars reticulata (SNR) and/or the deeper layers of the superior colliculus (dl-SC) in cats. Therefore, cats were trained to walk from one side of a narrow bar to the other side both under full light and under stroboscopic illumination (2 flashes/s). Previously it has been shown that this set-up is useful for assessing changes in the execution of dl-SC and SNR-related non-externally guided targeting movements. Moreover, cats were trained to step out of a startbox on a rotating cylinder which, according to previous studies, also implies the execution of a dl-SC- and SNR-related non-externally guided targeting movement. CN application of 25 micrograms/5 microliters haloperidol, but not CN injection of 12.5 micrograms/5 microliters haloperidol or apomorphine (0.6 micrograms/5 microliters), reduced the occurrence of these dl-SC- and SNR-related targeting movements. Dl-SC injection of picrotoxin (100 ng/0.5 microliter) did not restore the haloperidol (25 micrograms/5 microliter) induced decrement in the occurrence of these targeting movements. In addition, CN application of 25 micrograms/5 microliter haloperidol, but not 12.5 micrograms/5 microliter haloperidol, reduced the feline ability to execute SNR-specific limb movements while crossing a revolving cylinder. The present results show that only a severe but not a moderate inhibition of dopamine receptors within the CN affects motor expressions characteristic of the SNR and/or dl-SC.
authors: Department of Pharmacology, University of Nijmegen, The Netherlands.
authors: M
authors: M
authors: Gelissen
authors: A
authors: A
authors: Cools
mesh_terms: D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D002415:Cats; D002421:Caudate Nucleus / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006220:Haloperidol / Q000008:administration & dosage / Q000494:pharmacology*; D008029:Lighting; D008297:Male; D009048:Motor Skills / Q000187:drug effects*; D009068:Movement / Q000187:drug effects; D010852:Picrotoxin / Q000494:pharmacology; D011954:Receptors, Dopamine / Q000187:drug effects; D013378:Substantia Nigra / Q000187:drug effects*; D013477:Superior Colliculi / Q000187:drug effects*
chemical_list: D001058:Apomorphine; D006220:Haloperidol; D010852:Picrotoxin; D011954:Receptors, Dopamine