Effects of electroacupuncture intervention at different time in A day on expression of tyrosine hydroxylase and C-fos in nucleus accumbens in ketamine addiction rats

Objective: To observe the effect of electroacupuncture (EA) intervention at different time in a day on the expression of tyrosine hydroxylase (TH) and c-fos in the Nucleus Accumbens (NAc) so as to explore its mechanism underlying improvement of ketamine addiction.

Methods: A total of 56 Sprague-Dawley rats were randomized into normal control, normal saline (2 mL/kg), model and EA groups. The EA group was subdivided into Zi-Shi (23:00), Mao-Shi (05:00), Wu-Shi (11:00) and You-Shi (17: 00) subgroups. Ketamine addiction model was established by intraperitoneal administration of ketamine (100 mg/kg), once a day for 7 days. EA (2 Hz, 3 V) was applied to unilateral "Zusanli" (ST 36) and "Sanyinjiao" (SP 6) for 30 min, once daily for 7 days. The expression of TH and c-fos in the NAc was detected by immunohistochemistry.

Results: Compared with the normal control group and normal saline group, the numbers of TH and c-fos immunoreaction (IR)-positive neurons in NAc in the model group were upregulated significantly (P < 0.01). Compared with the model group, the expression levels of both TH and c-fos IR-positive neurons were down-regulated significantly in the Wu-Shi(11:00) and You-Shi (17:00) subgroups (P < 0.01), rather than in the Zi-Shi and Mao-Shi subgroups (P > 0.05).

Conclusions: EA of "Zusanli" (ST 36) and "Sanyinjiao" (SP 6) at 11:00 and 17:00 of the daytime can down-regulate ketamine addiction induced increase of expression of TH and c-fos in the NAc in ketamine addiction rats, which may contribute to its effect in relieving ketamine addiction symptoms in clinic.