title: Ovarian steroids regulate neuropeptides in the trigeminal ganglion.
abstract: Women are more than three times as likely as men to experience migraine headaches and temporomandibular joint pain, and painful episodes are often linked to the menstrual cycle. To understand how hormone levels may influence head and face pain, we assessed expression of pain-associated neuropeptides and estrogen receptor alpha (ERalpha) during the natural estrous cycle in mice. Gene expression was analyzed in the trigeminal ganglia of cycling female mice at proestrus, estrus and diestrus using RT-PCR. Peptide/protein expression in trigeminal neurons was analyzed using immunohistochemistry. ERalpha mRNA was present at all stages and highest at estrus. ERalpha protein was present in the cytoplasm of medium-sized and small trigeminal neurons. ERalpha immunoreactive neurons were most common at diestrus. CGRP and ANP mRNAs did not change across the estrous cycle, while expression of galanin and NPY mRNAs were strongly linked to the estrous cycle. Galanin mRNA levels peaked at proestrus, when expression was 8.7-fold higher than the diestrus levels. Galanin immunoreactivity also peaked at proestrus. At proestrus, 7.5% of trigeminal neurons contained galanin, while at estrus, 6.2% of trigeminal neurons contained galanin, and at diestrus, 4.9% of trigeminal neurons contained galanin. NPY mRNA peaked at estrus, when levels were 4.7-fold higher than at diestrus. Our findings suggest that estrogen receptors in trigeminal neurons modulate nociceptive responses through effects on galanin and NPY. Variations in neuropeptide content in trigeminal neurons across the natural estrous cycle may contribute to increases in painful episodes at particular phases of the menstrual cycle.
authors.affiliation: Department of Anatomy and Cell Biology, University Kansas Medical Center, 3901 Rainbow Blvd., Mail Stop 3038, Kansas City, KS 66160, USA.
authors.forename: Veena
authors.initials: V
authors.lastname: Puri
authors.forename: Lisa
authors.initials: L
authors.lastname: Cui
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Liverman
authors.forename: Kathy F
authors.initials: KF
authors.lastname: Roby
authors.forename: Robert M
authors.initials: RM
authors.lastname: Klein
authors.forename: K Michael A
authors.initials: KM
authors.lastname: Welch
authors.forename: Nancy E J
authors.initials: NE
authors.lastname: Berman
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000378:metabolism; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics / Q000378:metabolism; D004031:Diestrus / Q000502:physiology; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism; D004967:Estrogens / Q000502:physiology; D030762:Estrous Cycle / Q000502:physiology*; D004971:Estrus / Q000502:physiology; D005157:Facial Pain / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D019004:Galanin / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D009478:Neuropeptide Y / Q000235:genetics* / Q000378:metabolism; D010053:Ovary / Q000502:physiology; D011359:Proestrus / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012668:Trigeminal Ganglion / Q000502:physiology*
chemical_list: D047628:Estrogen Receptor alpha; D004967:Estrogens; D009478:Neuropeptide Y; D009320:Atrial Natriuretic Factor; D019004:Galanin; D015740:Calcitonin Gene-Related Peptide