Table 2.
Measures of pentazocine analgesia in humans by sex, hair, and skin phenotypes and MC1R genotype
| Sex | Hair color*
|
Skin type†
|
MC1R genotype‡
|
||||
|---|---|---|---|---|---|---|---|
| RH | NonRH | I & II | III & IV | Two variant alleles | 0/1 variant alleles | ||
| Number of subjects | Females | 9 | 9 | 11 | 7 | 5 | 13 |
| Males | 12 | 12 | 15 | 9 | 9 | 15 | |
| Δ Ischemic pain threshold§ | Females | 85.2 | 6.6 | 97.4 | −35.0 | 116.6 | 18.7 |
| (145.7) | (139.2) | (148.4) | (97.8) | (181.7) | (124.5) | ||
| Males | 17.4 | 98.3 | 20.2 | 120.6 | 8.8 | 87.3 | |
| (106.7) | (164.3) | (95.5) | (186.1) | (119.7) | (149.3) | ||
| Δ Ischemic pain tolerance¶ | Females | 237.0 | 62.0 | 233.3 | 24.8 | 408.0†† | 37.1 |
| (268.3) | (58.8) | (236.4) | (61.1) | (284.1) | (82.8) | ||
| Males | 62.3 | 84.6 | 84.6 | 59.6 | 46.4 | 84.1 | |
| (217.8) | (137.4) | (190.6) | (155.1) | (149.3) | (182.8) | ||
| Δ Sum ischemic pain intensity‖ | Females | 55.0 | 16.6 | 58.4†† | 0.3 | 84.8†† | 16.9 |
| (58.1) | (42.1) | (54.0) | (26.6) | (50.3) | (41.9) | ||
| Males | 20.9 | 40.3 | 25.4 | 39.3 | 18.7 | 37.8 | |
| (37.2) | (37.6) | (35.1) | (42.8) | (36.2) | (38.3) | ||
| Δ Sum ischemic pain unpleasantness** | Females | 46.1 | 11.1 | 54.4†† | −11.9 | 79.6†† | 9.0 |
| (60.0) | (51.8) | (55.6) | (31.9) | (45.7) | (49.6) | ||
| Males | 26.4 | 33.0 | 26.9 | 34.3 | 24.2 | 33.0 | |
| (48.1) | (44.4) | (43.3) | (51.1) | (41.0) | (49.0) | ||
| Δ Sum thermal pain intensity‡‡ | Females | −1.4 | −15.9 | 6.1 | −31.9 | 28.0†† | −22.8 |
| (56.1) | (38.9) | (46.9) | (41.1) | (48.9) | (40.1) | ||
| Males | 17.7 | 22.4 | 13.9 | 29.8 | 9.2 | 26.2 | |
| (48.8) | (61.9) | (46.4) | (66.6) | (51.0) | (56.5) | ||
Values presented are means (SD appears in parentheses). For all measures, greater values indicate more robust analgesia.
Redhead (RH) includes auburn (two) and strawberry (three) hair colors; NonRH includes blonde (five), brown (fourteen), and black (two). As seen by others previously (27), all subjects with two variant alleles were RH, but only 12 of 21 (57%) RH subjects had two variant alleles.
Based on Fitzpatrick skin type classifications: I: burn, never tan; II: burn, then tan; III: tan, sometimes burn; IV: tan, never burn. All subjects with two variant alleles had type I or type II skin.
Of the 14 subjects (29%) with two variant alleles, three were homozygous for R151C, one was homozygous for D294H, six were R151C/R160W compound heterozygotes, two were R151C/D294H compound heterozygotes, and one was a V92M/R160W compound heterozygote. Other than V92M, R151C, R160W, and D294H, the only nonconsensus allele observed was R163Q in one non-RH female. Observed allelic frequencies were very similar to published data (27).
Calculated as: (postdrug pain threshold − predrug pain threshold).
Calculated as: (postdrug pain tolerance − predrug pain tolerance).
Calculated as: (sum of all predrug ischemic pain intensity ratings − sum of all postdrug ischemic pain intensity ratings).
Calculated as: (sum of all predrug ischemic pain unpleasantness ratings − sum of all postdrug ischemic pain unpleasantness ratings).
Calculated as: (sum of predrug thermal pain intensity ratings trials 1–5 − sum of postdrug pain thermal intensity ratings trials 1–5).
Significantly higher than corresponding within-sex group, P < 0.05 (see text).