Abstract
The present study has investigated whether circulating estrogen level variations in the pro-estrus and estrus phases of the intact rats and estrogen depletion in the ovariectomized animals (OVX) adjust the formalin-induced nociceptive behaviors. During the pro-estrus and estrus phases of rats' estrus cycle and in the OVX rats, 17β-estradiol and ICI 182,780 (estrogen receptor antagonist) were administered into the right paragigantocellularis lateralis (LPGi) nucleus. Then, the formalin-induced flexing and licking responses were recorded for 60min. The findings of this study revealed that intra-LPGi administration of 17β-estradiol (0.8μmol) reduced the formalin-induced flexing and licking duration in pro-estrus and estrus rats (P < 0.001), suggesting an analgesic effect. 17β-Estradiol injection into the LPGi nucleus of OVX rats increased the flexing duration (P < 0.05) while decreasing the licking duration (P < 0.05) of the formalin test. The pain modulatory effect of 17β-estradiol on the flexing response was reversed by ICI 182,780 (15nmol) in the pro-estrus (P < 0.001) and estrus rats (P < 0.001) but not in the OVX rats. Also, pretreatment of LPGi nucleus with ICI 182,780 reversed the analgesic effect of 17β-estradiol on the licking response in the pro-estrus (P < 0.05), estrus (P < 0.001), and OVX rats (P < 0.001). These results suggest that the pain threshold in intact female rats is modulated independently of the estrus state. Still, the basal level of plasma estrogen and the activation of its receptors are necessary for pain modulation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Similar Papers
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.