[Effects of intra-periaqueductal gray injection of zeta pseudosubstrate inhibitory peptide on sensory and affective components of pain].
OBJECTIVE
To explore the effects of intra-PAG injection of ZIP on sensory and affective components of pain.


METHODS
For determining the role of ZIP on pain-induced aversion, the effects of intra-PAG injection of ZIP on formalin-induced conditioned place avoidance (F-CPA) was investigated. To determine the role of ZIP on pain perception, formalin-induced inflammatory pain model was established and the effects of intra-PAG injection of ZIP on formalin-induced nociceptive behaviors was investigated.


RESULTS
In the NS-treated rats, the time in the pain-paired compartment during the test session was significantly shorter than that during the preconditioning session 2 and 24 hours after administration of the drug at both 1 and 7 day post-training (Group NS-1 d-2 h: (465.1 ± 40.6) vs (133.8 ± 29.4) s (P < 0.001); Group NS-7 d-2 h: (432.3 ± 43.7) vs (150.5 ± 26.6) s (P < 0.01); Group NS-1 d-24 h: (500.5 ± 20.6) vs (107.0 ± 15.7) s (P < 0.001); Group NS-7 d-24 h: (450.8 ± 27.4) vs (129.4 ± 21.1) s (P < 0.001)). On the contrary, in the ZIP-treated rats, no significant differences were observed in the time in the pain-paired compartment between the post-conditioning and pre-conditioning sessions at the same time-points. CPA scores also showed the attenuation of F-CPA by intra-PAG injection of ZIP in comparison to the saline-injected rats (P < 0.05). Compared with the intra-PAG saline-injected group, intra-PAG microinjection of ZIP did not affect the formalin-induced nociceptive behaviors (P > 0.05).


CONCLUSIONS
The study suggests that PAG contributes to pain-related aversion in rats, and the mechanism of pain emotion encoding in PAG may attribute to the activation of targets of ZIP.
Department of Anesthesiology, Ningbo NO.2 Hospital, Ningbo 315010, China.
Bo
B
Lu
Yaqin
Y
Huang
Weiping
W
Lei
Juan
J
Yao
Junping
J
Chen
Chun
C
Xiao
Email:jxmzsjl@163.com.
Jianliang
J
Sun
D000818:Animals; D005557:Formaldehyde; D010146:Pain; D010147:Pain Measurement; D010455:Peptides; D010487:Periaqueductal Gray; D051381:Rats
D010455:Peptides; D005557:Formaldehyde