title: Androgen and estrogen receptor-beta distribution within spinal-projecting and neurosecretory neurons in the paraventricular nucleus of the male rat.
abstract: Activation of the hypothalamic-pituitary-adrenal (HPA) axis is initiated by neurosecretory neurons residing within the medial parvicellular part of the hypothalamic paraventricular nucleus (PVN). Despite the potency by which sex steroids operate on HPA and medial parvocellular responses to stress, previous topographic and phenotypic studies suggest that gonadal steroid hormone receptors are scarcely, if at all, expressed by PVN neurons controlling anterior pituitary corticotropes. Guided by the pattern of retrograde accumulation of fluorogold, we used a direct connectional approach to define the distribution of androgen receptors (AR) and estrogen-beta receptors (ER-beta) within populations of neurosecretory vs. nonneurosecretory neurons in the PVN. Juxtaposition of AR-immunoreactivity (ir) and ER-beta mRNA to the pattern of intravenous fluorogold labeling showed these steroid hormone receptors to be concentrated within portions of the PVN devoid of neurosecretory neurons. Superimposing receptor profiles onto the pattern of spinal retrograde labeling confirmed a selective distribution of AR-ir within autonomic-related cells of the medial parvocellular division, including its dorsal, lateral, and ventral medial components. ER-beta mRNA expression was likewise concentrated within regions accumulating spinal tracer, highest within the ventral aspect of the PVN. These results indicate a direct influence of gonadal hormones on preautonomic effector neurons and remain in keeping with an indirect influence of androgens on adrenocorticotropin-regulating neurons in the PVN.
authors.affiliation: Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
authors.forename: Brenda
authors.initials: B
authors.lastname: Bingham
authors.forename: Martin
authors.initials: M
authors.lastname: Williamson
authors.forename: Victor
authors.initials: V
authors.lastname: Viau
mesh_terms: D000728:Androgens / Q000378:metabolism; D000818:Animals; D004525:Efferent Pathways / Q000166:cytology / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000235:genetics*; D004967:Estrogens / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D009490:Neurosecretory Systems / Q000166:cytology / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011944:Receptors, Androgen / Q000378:metabolism*; D012098:Reproduction / Q000502:physiology; D012727:Sex Characteristics; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*
chemical_list: D000728:Androgens; D047629:Estrogen Receptor beta; D004967:Estrogens; D012333:RNA, Messenger; D011944:Receptors, Androgen