Figure 4

Experiment #2: Meal duration and von Frey filament testing of male rats after virus injection. Rats were injected with virus and then 72 hours post-injection a ligature was placed around the tendon of the masseter muscle. Meal duration (panel A) was reported for 6 days before ligature surgery (−6, −5, −4, −3, −2, −1) and for 4 days after ligature surgery (1, 2, 3, 3). Filament testing was reported for day 7 before ligature surgery (-7) and 7, 14 and 21 days post-virus injection or 4, 11 and 18 days post-ligature (panel B). Groups received either a vehicle injection or an injection of virus that did not contain an enkephalin transgene (control virus, SHZ) or a virus that had an enkephalin transgene (SHPE) on day −4. In panel A the significant differences (p < 0.05) between the vehicle/ligature, SHZ virus/ligature and their respective sham groups are indicated by an asterisk and significant differences (p < 0.05) between the vehicle/ligature and SHZ/ligature versus the SHPE virus/ligature group are indicated by a “#”. In panel B significant differences (p < 0.05) between all the ligature groups and their respective sham groups are indicated by an asterisk and significant differences (p < 0.05) between the vehicle/ligature and SHZ/ligature versus the SHPE virus/ligature group is indicated by a “#”. Values are the means ± SEM. See Table 2 for the number of animals per group.