title: Effect of estrogen on vagal afferent projections to the brainstem in the female.
abstract: The effects of 17β-estradiol (E) on the distribution and density of brainstem projections of small or large diameter primary vagal afferents were investigated in Wistar rats using transganglionic transport of wheat germ agglutinin- (WGA; preferentially transported by non-myelinated afferent C-fibers; 2%), or cholera toxin B-subunit- (CTB, 5%; preferentially transported by large myelinated afferent A-fibers) conjugated horseradish peroxidase (HRP) in combination with the tetramethylbenzidine method in age matched ovariectomized (OVX) only or OVX and treated with E (OVX+E; 30 pg/ml plasma) females for 12 weeks. Additionally, these projections were compared to aged matched males. Unilateral microinjection of WGA-HRP into the nodose ganglion resulted in dense anterograde labeling bilaterally, with an ipsilateral predominance in several subnuclei of the nucleus of the solitary tract (NTS) and in area postrema that was greatest in OVX+E animals compared to OVX only and males. Moderately dense anterograde labeling was also observed in paratrigeminal nucleus (PAT) of the OVX+E animals. CTB-HRP produced less dense anterograde labeling in the NTS complex, but had a wider distribution within the brainstem including the area postrema, dorsal motor nucleus of the vagus, PAT, the nucleus ambiguus complex and ventrolateral medulla in all groups. The distribution of CTB-HRP anterograde labeling was densest in OVX+E, less dense in OVX only females and least dense in male rats. Little, if any, labeling was found within PAT in males using either WGA-or CTB-HRP. Taken together, these data suggest that small, non-myelinated (WGA-labeled) and large myelinated (CTB-labeled) diameter vagal afferents projecting to brainstem autonomic areas are differentially affected by circulating levels of estrogen. These effects of estrogen on connectivity may contribute to the sex differences observed in central autonomic mechanisms between gender, and in females with and without estrogen.
authors.affiliation: Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1 Canada. Electronic address: john.ciriello@schulich.uwo.ca.
authors.forename: John
authors.initials: J
authors.lastname: Ciriello
authors.affiliation: Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5C1 Canada.
authors.forename: Monica M
authors.initials: MM
authors.lastname: Caverson
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000033:anatomy & histology* / Q000378:metabolism; D002772:Cholera Toxin / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D007839:Functional Laterality; D006735:Horseradish Peroxidase / Q000378:metabolism; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D009620:Nodose Ganglion / Q000502:physiology; D010052:Ovariectomy; D051381:Rats; D012727:Sex Characteristics; D014630:Vagus Nerve / Q000502:physiology*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate / Q000378:metabolism
chemical_list: D004967:Estrogens; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; C052635:cholera toxin, B subunit-horseradish peroxidase; D004958:Estradiol; D002772:Cholera Toxin; D006735:Horseradish Peroxidase
keywords: 17 β-estradiol; Brainstem; Cholera toxin B-subunit-horseradish peroxidase; Ovariectomy; Transganglionic transport; Vagus nerve; Wheat germ agglutinin-horseradish peroxidase