The Influence of Sex Steroid Hormone Fluctuations on Capsaicin-Induced Pain and TRPV1 Expression

• Published in: International journal of molecular sciences Vol. 25; no. 15; p. 8040
• Main Authors: Mota-Carrillo, Edgardo, Juárez-Contreras, Rebeca, González-Ramírez, Ricardo, Luis, Enoch, Morales-Lázaro, Sara Luz
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01-08-2024
• Subjects: Animals; Capsaicin; Capsaicin - pharmacology; diestrus; Estrogen; Estrogens; Estrous Cycle - drug effects; Female; Females; Fibromyalgia; Ganglia, Spinal - drug effects; Ganglia, Spinal - metabolism; Gender differences; Gene expression; Gene Expression Regulation - drug effects; Gonadal Steroid Hormones - metabolism; Hormones; International economic relations; Irritable bowel syndrome; Male; Males; Mice; Neurons; Pain; Pain - genetics; Pain - metabolism; Pain Threshold - drug effects; Phenols; proestrus; Protein expression; Proteins; Rheumatoid arthritis; RNA; RNA, Messenger - genetics; RNA, Messenger - metabolism; Scientific equipment and supplies industry; Sex Characteristics; Sexes; Steroids; Trigeminal Ganglion - drug effects; Trigeminal Ganglion - metabolism; TRPV Cation Channels - genetics; TRPV Cation Channels - metabolism; TRPV1; United States; Mexico; Massachusetts; estrogens; proestrus; pain; TRPV1; hormones; diestrus
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms25158040

Sexual dimorphism among mammals includes variations in the pain threshold. These differences are influenced by hormonal fluctuations in females during the estrous and menstrual cycles of rodents and humans, respectively. These physiological conditions display various phases, including proestrus and diestrus in rodents and follicular and luteal phases in humans, distinctly characterized by varying estrogen levels. In this study, we evaluated the capsaicin responses in male and female mice at different estrous cycle phases, using two murine acute pain models. Our findings indicate that the capsaicin-induced pain threshold was lower in the proestrus phase than in the other three phases in both pain assays. We also found that male mice exhibited a higher pain threshold than females in the proestrus phase, although it was similar to females in the other cycle phases. We also assessed the mRNA and protein levels of TRPV1 in the dorsal root and trigeminal ganglia of mice. Our results showed higher TRPV1 protein levels during proestrus compared to diestrus and male mice. Unexpectedly, we observed that the diestrus phase was associated with higher TRPV1 mRNA levels than those in both proestrus and male mice. These results underscore the hormonal influence on TRPV1 expression regulation and highlight the role of sex steroids in capsaicin-induced pain.