title: Topographic distribution of serotonin-immunoreactive urethral endocrine cells and their relationship with calcitonin gene-related peptide-immunoreactive nerves in male rats.
abstract: We investigated the topographic distribution and morphology of serotonin (5-HT)-immunoreactive endocrine cells in the urethra of male rats, and focused on their relationship with peptidergic nerve fibers immunoreactive for calcitonin gene-related peptide (CGRP). Urethral endocrine cells immunoreactive for 5-HT were densely distributed in the epithelial layers of the prostatic part, but were sparsely distributed in the membranous and spongy parts of urethra. Distribution of urethral endocrine cells with 5-HT immunoreactivity in the prostatic part was restricted from the internal urethral orifice to the region of seminal colliculus. 5-HT-immunoreactive endocrine cells were also observed in the ductal epithelial layers of coagulating glands, prostatic glands, and seminal vesicles. 5-HT-immunoreactive endocrine cells were triangular or flask in shape and possessed an apical projection extending toward the urethral lumen, and basal or lateral protrusions intruding between other epithelial cells were also detected in some cells. Double immunolabeling for 5-HT and CGRP revealed that CGRP-immunoreactive nerve fibers attached to urethral endocrine cells with 5-HT immunoreactivity in the prostatic part. These results suggest that urethral endocrine cells may release 5-HT in response to luminal stimuli, and that these cells and CGRP-immunoreactive nerves may regulate each other by an axon reflex mechanism.
authors.affiliation: Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan. Electronic address: ytakuya@iwate-med.ac.jp.
authors.forename: Takuya
authors.initials: T
authors.lastname: Yokoyama
authors.affiliation: Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Saino
authors.affiliation: Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Nakamuta
authors.affiliation: Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D002116:Calcitonin / Q000235:genetics / Q000378:metabolism*; D015740:Calcitonin Gene-Related Peptide / Q000235:genetics / Q000378:metabolism*; D055098:Endocrine Cells / Q000378:metabolism* / Q000648:ultrastructure; D015870:Gene Expression; D007150:Immunohistochemistry; D008297:Male; D009412:Nerve Fibers / Q000378:metabolism / Q000648:ultrastructure; D011467:Prostate / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D012669:Seminal Vesicles / Q000378:metabolism / Q000648:ultrastructure; D012701:Serotonin / Q000378:metabolism*; D015398:Signal Transduction; D014521:Urethra / Q000378:metabolism* / Q000648:ultrastructure; D001743:Urinary Bladder / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D012701:Serotonin; D002116:Calcitonin; D015740:Calcitonin Gene-Related Peptide
keywords: Calcitonin gene-related peptide; Endocrine cells; Immunohistochemistry; Serotonin; Urethra