Localization and regulation of reproductive steroid receptors in the raphe serotonin system of male macaques

Cynthia Bethea, Kenny Phu, Yelena Belikova, Sarah C. Bethea

    Research output: Contribution to journalArticle

    8 Citations (Scopus)

    Abstract

    We previously showed that tryptophan hydroxylase 2 (TPH2) and serotonin reuptake transporter (SERT) mRNAs are increased by the androgens, testosterone (T) and dihydrotestosterone (DHT) in serotonin neurons of male macaques. In addition, we observed that serotonin in axons of a terminal region were markedly decreased by aromatase inhibition and lack of estradiol (E) from metabolism of T. These observations implicated androgen receptors (AR) and estrogen receptors (ER) in the transduction of steroid hormone actions in serotonin neurons. Due to the longer treatment period employed, the expression of the cognate nuclear receptors was sought. We used single and double immunohistochemistry to quantitate and phenotypically localize AR, ERα and ERβ in the dorsal raphe of male macaques. Male Japanese macaques (Macaca fuscata) were castrated for 5-7 months and then treated for 3 months with [1] placebo, [2] T, [3] DHT (non-aromatizable androgen) plus ATD (steroidal aromatase inhibitor), or [4] Flutamide (FLUT; androgen antagonist) plus ATD (n= 5/group). After single labeling of each receptor, quantitative image analysis was applied and receptor positive neurons were counted. Double-label of raphe neurons for each receptor plus TPH2 determined whether the receptors were localized in serotonin neurons. There were significantly more AR-positive neurons in T- and DHT. +. ATD-treated groups (p= 0.0014) compared to placebo or FLUT. +. ATD-treated groups. There was no difference in the number of positive-neurons stained for ERα or ERβ{dot operator} Double-immunohistochemistry revealed that serotonin neurons did not contain AR. Rather, AR-positive nuclei were found in neighboring cells that are likely neurons. However, approximately 40% of dorsal raphe serotonin neurons contained ERα or ERβ{dot operator} In conclusion, the stimulatory effect of androgens on TPH2 and SERT mRNA expression is mediated indirectly by neighboring neurons contain AR. The stimulatory effect of E, derived from T metabolism, on serotonin transport is partially mediated directly via nuclear ERs.

    Original languageEnglish (US)
    Pages (from-to)19-27
    Number of pages9
    JournalJournal of Chemical Neuroanatomy
    Volume66-67
    DOIs
    StatePublished - Jul 1 2015

    Fingerprint

    Steroid Receptors
    Macaca
    Serotonin
    Neurons
    Estrogen Receptors
    Androgen Receptors
    Tryptophan Hydroxylase
    Dihydrotestosterone
    Androgens
    Serotonin Plasma Membrane Transport Proteins
    Immunohistochemistry
    Placebos
    Flutamide
    Androgen Antagonists
    Messenger RNA
    Aromatase Inhibitors
    Aromatase
    Presynaptic Terminals
    Cytoplasmic and Nuclear Receptors
    Testosterone

    Keywords

    • Androgen receptors
    • Estrogen receptors
    • Macaque
    • Male
    • Serotonin

    ASJC Scopus subject areas

    • Cellular and Molecular Neuroscience

    Cite this

    Localization and regulation of reproductive steroid receptors in the raphe serotonin system of male macaques. / Bethea, Cynthia; Phu, Kenny; Belikova, Yelena; Bethea, Sarah C.

    In: Journal of Chemical Neuroanatomy, Vol. 66-67, 01.07.2015, p. 19-27.

    Research output: Contribution to journalArticle

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    AB - We previously showed that tryptophan hydroxylase 2 (TPH2) and serotonin reuptake transporter (SERT) mRNAs are increased by the androgens, testosterone (T) and dihydrotestosterone (DHT) in serotonin neurons of male macaques. In addition, we observed that serotonin in axons of a terminal region were markedly decreased by aromatase inhibition and lack of estradiol (E) from metabolism of T. These observations implicated androgen receptors (AR) and estrogen receptors (ER) in the transduction of steroid hormone actions in serotonin neurons. Due to the longer treatment period employed, the expression of the cognate nuclear receptors was sought. We used single and double immunohistochemistry to quantitate and phenotypically localize AR, ERα and ERβ in the dorsal raphe of male macaques. Male Japanese macaques (Macaca fuscata) were castrated for 5-7 months and then treated for 3 months with [1] placebo, [2] T, [3] DHT (non-aromatizable androgen) plus ATD (steroidal aromatase inhibitor), or [4] Flutamide (FLUT; androgen antagonist) plus ATD (n= 5/group). After single labeling of each receptor, quantitative image analysis was applied and receptor positive neurons were counted. Double-label of raphe neurons for each receptor plus TPH2 determined whether the receptors were localized in serotonin neurons. There were significantly more AR-positive neurons in T- and DHT. +. ATD-treated groups (p= 0.0014) compared to placebo or FLUT. +. ATD-treated groups. There was no difference in the number of positive-neurons stained for ERα or ERβ{dot operator} Double-immunohistochemistry revealed that serotonin neurons did not contain AR. Rather, AR-positive nuclei were found in neighboring cells that are likely neurons. However, approximately 40% of dorsal raphe serotonin neurons contained ERα or ERβ{dot operator} In conclusion, the stimulatory effect of androgens on TPH2 and SERT mRNA expression is mediated indirectly by neighboring neurons contain AR. The stimulatory effect of E, derived from T metabolism, on serotonin transport is partially mediated directly via nuclear ERs.

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