Table 1.

In vitro pharmacological profile of NOP agonists in binding and functional assays at the opioid receptors^*

	Receptor Binding Ki (nM)				[35S] GTPγS NOP		[35S] GTPγS MOP		[35S] GTPγS KOP
	NOP	MOP	KOP	DOP	EC50 (nM)	% Stim	EC50 (nM)	% Stim	EC50 (nM)	% Stim
N/OFQ	0.08 ± 0.03	133 ± 30	247 ± 3.4	ND	4.0 ± 0.1	100	>10,000		>10,000
DAMGO		2.96 ± 0.54					32.6 ± 4.06	100
DPDPE				1.11 ± 0.07
U69,593			1.05 ± 0.02						60.14 ± 7.45	100
AT-312	0.34 ± 0.13	5.99 ± 0.97	73.5 ± 28.3	128.7± 57.4	29.9 ± 1.4	102.3 ± 0.75	81.5 ± 15.9	24.6 ± 2.4	>10,000	-
SCH221510	13.7 ± 2.30	65.4 ± 11.3	49.7 ± 11.3	403.7 ± 109.7	18.9 ± 5.9	95.1 ± 7.8	139.3 ± 4.6	76.8 ± 13.1	142.0 ± 15.6	82.72 ± 0.22

^*GTP(γ)S functional assays only carried out if binding affinity Ki<100 nM. The functional efficacy at the delta opioid receptor was therefore not determined for AT-312 and SCH221510. Values are the Mean ± SEM of three independent experiments run in triplicate. Functional activity was determined by stimulation of [³⁵S]GTPγS binding to cell membranes, % stimulation was obtained as a percentage of stimulation of the standard agonists N/OFQ (for NOP), DAMGO (for MOP) and U69,593 (for KOP) taken as 100%.