Turning behaviour following nigral injections of dopamine agonists and glycine

Glycine, ADTN and ergometrine, but not LSD, induced strong dose-related contraversive turning following unilateral microinjections into the substantia nigra (zona reticulata) of conscious rats. The responses to glycine and ADTN were blocked by low doses of systemically injected cis-Z-flupenthixol but were unaffected by pretreatment with a variety of dopamine antagonists injected intranigrally. Turning behaviour following glycine was antagonised by strychnine but that to ADTN was not. Possible ways by which the rotational responses may be induced in view of the postulated neuronal circuitry of the substantia nigra and its connections with other brain areas are discussed.