Dopamine-dependent behavioural stimulation by non-peptide delta opioids BW 373U86 and SNC 80:: 3.: Facilitation of D1 and D2 responses in unilaterally 6-hydroxydopamine-lesioned rats

In unilaterally 6-hydroxydopamine lesioned rats the ability of two non-peptide delta-opioid agonists, BW 373U86 and SNC 80, to induce motor asymmetries, alone or in combination with low doses of specific D-1 or D-2 agonists, was investigated. BW 373U86 and SNC 80 failed to induce motor asymmetries by themselves, but elicited contralateral turning after pretreatment with a dose of SKF 38393, a D-1 agonist, or quinpirole, a D-2 agonist, which per se did not induce contralateral turning. BW 373U86 also potentiated contralateral turning induced by threshold doses of quinpirole. Facilitation of D-1-dependent contralateral turning was associated with a potentiation of c-fos expression, as estimated by Fos-like immunoreactivity, in the dorsal caudate-putamen, particularly in its lateral aspect. Potentiation of D-2-dependent contralateral turning was associated with a reduction of c-fos expression in the medial caudate-putamen. It is concluded that stimulation of delta-opioid receptors facilitates the expression of D-1 and D-2 responses arising from the denervated striatum.