title: Adaptive plasticity of vaginal innervation in term pregnant rats.
abstract: Changes in reproductive status place varied functional demands on the vagina. These include receptivity to male intromission and sperm transport in estrus, barrier functions during early pregnancy, and providing a conduit for fetal passage at parturition. Peripheral innervation regulates vaginal function, which in turn may be influenced by circulating reproductive hormones. We assessed vaginal innervation in diestrus and estrus (before and after the estrous cycle surge in estrogen), and in the early (low estrogen) and late (high estrogen) stages in pregnancy. In vaginal sections from cycling rats, axons immunoreactive for the pan-neuronal marker protein gene product 9.5 (PGP 9.5) showed a small reduction at estrus relative to diestrus, but this difference did not persist after correcting for changes in target size. No changes were detected in axons immunoreactive for tyrosine hydroxylase (sympathetic), vesicular acetylcholine transporter (parasympathetic), or calcitonin gene-related peptide and transient receptor potential vanilloid type 1 (TRPV-1; sensory nociceptors). In rats at 10 days of pregnancy, innervation was similar to that observed in cycling rats. However, at 21 days of pregnancy, axons immunoreactive for PGP 9.5 and each of the subpopulation-selective markers were significantly reduced both when expressed as percentage of sectional area or after correcting for changes in target size. Because peripheral nerves regulate vaginal smooth muscle tone, blood flow, and pain sensitivity, reductions in innervation may represent important adaptive mechanisms facilitating parturition.
authors.affiliation: Institute for Neurological Disorders, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Liao
authors.forename: Peter G
authors.initials: PG
authors.lastname: Smith
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001369:Axons / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D004031:Diestrus / Q000378:metabolism; D004971:Estrus / Q000378:metabolism; D005260:Female; D005865:Gestational Age; D007150:Immunohistochemistry; D009473:Neuronal Plasticity; D017933:Peripheral Nervous System / Q000378:metabolism / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D050916:TRPV Cation Channels / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000378:metabolism; D014621:Vagina / Q000294:innervation*; D050494:Vesicular Acetylcholine Transport Proteins / Q000378:metabolism
chemical_list: D015415:Biomarkers; C493461:Slc18a3 protein, rat; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D050494:Vesicular Acetylcholine Transport Proteins; D014446:Tyrosine 3-Monooxygenase; C489034:UCHL1 protein, rat; D043222:Ubiquitin Thiolesterase; D015740:Calcitonin Gene-Related Peptide