Table 2.

Experimental protocols

GroupNTreatmentDose(s)
I–A
124PGE2100 ng
216Clonidine + PGE2100 ng + 100 ng
36Clonidine hourly × 3100 ng × 3
412Clonidine hourly × 3, fourth hour clonidine + PGE2100 ng × 3, 100 ng + 100 ng
I–B
112DAMGO hourly × 3, fourth hour clonidine + PGE21 μg × 3, 100 ng + 100 ng
212CPA hourly × 3, fourth hour clonidine + PGE21 μg × 3, 100 ng + 100 ng
316Clonidine + PGE2100 ng + 100 ng
412Clonidine hourly × 3, fourth hour DAMGO + PGE2100 ng × 3, 1 μg + 100 ng
56DAMGO + PGE21 μg + 100 ng
66DAMGO hourly × 31 μg × 3
76CPA hourly × 31 μg × 3
812Clonidine hourly × 3, fourth hour CPA + PGE2100 ng × 3, 1 μg + 100 ng
96CPA + PGE21 μg + 100 ng
II-A
124PGE2100 ng
216Clonidine + PGE2100 ng + 100 ng
36Clonidine × 3100 ng × 3
48Clonidine hourly × 3, fourth hour yohimbine100 ng × 3, 100 ng
II-B
110Clonidine hourly × 3, fourth hour naloxone100 ng × 3, 200 ng
210Clonidine hourly × 3, fourth hour PACPX100 ng × 3, 100 ng
36Clonidine × 3100 ng × 3
410DAMGO hourly × 3, fourth hour yohimbine1 μg × 3, 100 ng
56DAMGO × 31 μg × 3
610CPA hourly × 3, fourth hour yohimbine1 μg × 3, 100 ng
76CPA hourly × 31 μg × 3
III-A
124PGE2100 ng
26DAMGO + PGE21 μg + 100 ng
36Naloxone + DAMGO + PGE21 ng + 1 μg + 100 ng
46Naloxone + DAMGO + PGE210 ng + 1 μg + 100 ng
56Naloxone + DAMGO + PGE2100 ng + 1 μg + 100 ng
66Naloxone + DAMGO + PGE21 μg + 1 μg + 100 ng
III-B
124PGE2100 ng
216Clonidine + PGE2100 ng + 100 ng
36Yohimbine + clonidine + PGE21 ng + 100 ng + 100 ng
46Yohimbine + clonidine + PGE210 ng + 100 ng + 100 ng
56Yohimbine + clonidine + PGE2100 ng + 100 ng + 100 ng
66Yohimbine + clonidine + PGE21 μg + 100 ng + 100 ng
III-C
124PGE2100 ng
26CPA + PGE21 μg + 100 ng
36PACPX + CPA + PGE21 ng + 1 μg + 100 ng
46PACPX + CPA + PGE210 ng + 1 μg + 100 ng
56PACPX + CPA + PGE2100 ng + 1 μg + 100 ng
66PACPX + CPA + PGE21 μg + 1 μg + 100 ng
IV-A
124PGE2100 ng
216Clonidine + PGE2100 ng + 100 ng
36Yohimbine + clonidine + PGE2100 ng + 100 ng + 100 ng
410Naloxone + clonidine + PGE2200 ng + 100 ng + 100 ng
510PACPX + clonidine + PGE2100 ng + 100 ng + 100 ng
IV-B
124PGE2100 ng
26DAMGO + PGE21 μg + 100 ng
36Naloxone + DAMGO + PGE2200 ng + 1 μg + 100 ng
48Yohimbine + DAMGO + PGE2100 ng + 1 μg + 100 ng
56PACPX + DAMGO + PGE2100 ng + 1 μg + 100 ng
IV-C
124PGE2100 ng
26CPA + PGE21 μg + 100 ng
GroupNTreatmentDose(s)
IV-C
36PACPX + CPA + PGE2100 ng + 1 μg + 100 ng
48Naloxone + CPA + PGE2200 ng + 1 μg + 100 ng
56Yohimbine + CPA + PGE2100 ng + 1 μg + 100 ng
V-A
18Clonidine hourly × 3, fourth hour yohimbine100 ng × 3, 100 ng
26Clonidine hourly × 3, fourth hour clonidine + yohimbine100 ng × 3, 100 ng + 100 ng
38Clonidine hourly × 3, fourth hour DAMGO + yohimbine100 ng × 3, 1 μg + 100 ng
48Clonidine hourly × 3, fourth hour CPA + yohimbine100 ng × 3, 1 μg + 100 ng
V-B
16DAMGO hourly × 3, fourth hour naloxone1 μg × 3, 200 ng
26DAMGO hourly × 3, fourth hour DAMGO + naloxone1 μg + 1 μg + 200 ng
38DAMGO hourly × 3, fourth hour clonidine + naloxone1 μg + 100 ng + 200 ng
48DAMGO hourly × 3, fourth hour CPA + naloxone1 μg + 1 μg + 200 ng
V-C
18CPA hourly × 3, fourth hour PACPX1 μg × 3, 100 ng
26CPA hourly × 3, fourth hour CPA + PACPX1 μg + 1 μg + 100 ng
38CPA hourly × 3, fourth hour clonidine + PACPX1 μg + 100 ng + 100 ng
48CPA hourly × 3, fourth hour DAMGO + PACPX1 μg + 1 μg + 100 ng
VI-A
124PGE2100 ng
26DAMGO + PGE21 μg + 100 ng
36μ-antisense intrathecally alternate days × 3, 24 hr after DAMGO + PGE21 μg × 3, 1 μg + 100 ng
46μ-sense intrathecally alternate days × 3, 24 hr after DAMGO + PGE21 μg × 3, 1 μg + 100 ng
VI-B
124PGE2100 ng
216Clonidine + PGE2100 ng + 100 ng
36μ-antisense intrathecally alternate days × 3, 24 hr after clonidine + PGE21 μg × 3, 100 ng + 100 ng
46μ-sense intrathecally alternate days × 3, 24 hr after clonidine + PGE21 μg × 3, 100 ng + 100 ng
VI-C
124PGE2100 ng
26CPA + PGE21 μg + 100 ng
36μ-antisense intrathecally alternate days × 3, 24 hr after CPA + PGE21 μg × 3, 1 μg + 100 ng
46μ-sense intrathecally alternate days × 3, 24 hr after CPA + PGE21 μg × 3, 1 μg + 100 ng
VII-A
124PGE2100 ng
26DAMGO + PGE21 μg + 100 ng
36α2-antisense intrathecally alternate days × 3, 24 hr after DAMGO + PGE21 μg × 3, 1 μg + 100 ng
46α2-sense intrathecally alternate days × 3, 24 hr after DAMGO + PGE21 μg × 3, 1 μg + 100 ng
VII-B
124PGE2100 ng
216Clonidine + PGE2100 ng + 100 ng
36α2-antisense intrathecally alternate days × 3, 24 hr after clonidine + PGE21 μg × 3, 100 ng + 100 ng
46α2-sense intrathecally alternate days × 3, 24 hr after clonidine + PGE21 μg × 3, 100 ng + 100 ng
VII-C
124PGE2100 ng
26CPA + PGE21 μg + 100 ng
36α2-antisense intrathecally days × 3, 24 hr after CPA + PGE21 μg × 3, 1 μg + 100 ng
46α2-sense intrathecally alternate days × 3, 24 hr after CPA + PGE21 μg × 3, 1 μg + 100 ng
  • Abbreviations: PGE2, Prostaglandin E2 (EP receptor agonist); DAMGO, [d-Ala2, N-Me-Phe4, gly5-ol] (μ-opioid receptor agonist); Cl, clonidine (α2 agonist); Yo, yohimbine (α2 antagonist); CPA, N6-cyclopentyl adenosine (A1-adenosine agonist); PACPX, 1,3-dipropyl-8-(2-amino-4-chlorophenyl)-xanthine (A1-adenosine antagonist). There are repetitions for the sake of comparison.