[Effects of intra-periaqueductal gray injection of zeta pseudosubstrate inhibitory peptide on sensory and affective components of pain].

Abstract

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).

CONCLUSION:

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.

• Authors: Bo Lu, Yaqin Huang, Weiping Lei, Juan Yao, Junping Chen, Chun Xiao, Jianliang Sun
• Journal: Zhonghua yi xue za zhi (Zhonghua Yi Xue Za Zhi) Vol. 95 Issue 6 Pg. 444-8 (Feb 10 2015) ISSN: 0376-2491 [Print] China
• PMID: 25916782 (Publication Type: Journal Article)

Chemical References

• Peptides
• Formaldehyde

Topics

• Animals
• Formaldehyde
• Pain
• Pain Measurement
• Peptides
• Periaqueductal Gray
• Rats