Immunocytochemical colocalization of hypothalamic progestin receptors and tyrosine hydroxylase in steroid-treated monkeys

Steven Kohama, Francetta Freesh, Cynthia Bethea

    Research output: Contribution to journalArticle

    38 Citations (Scopus)

    Abstract

    Progesterone (P)-induced PRL secretion in estradiol (E)-primed monkeys is not due to direct pituitary stimulation, because lactotropes do not express progestin receptors (PR). However, the hypothalamus, particularly the tuberoinfundibular dopamineigic system (TIDA), plays a major role in the regulation of PRL secretion. To determine whether hypothalamic dopamine neurons are progestin target cells, the colocalization of PR and tyrosine hydroxylase (TH), a phenotypic marker of dopaminergic neurons, was examined with double immunocytochemistry. Two methods for visualizing the antigens were applied; the first was a dual peroxidase method, and the second was a peroxidase-alkaline phosphatase method. In addition, the question of whether E induces PR in dopamine neurons was explored. Spayed female monkeys were treated with empty Silastic capsules, E-filled capsules for a period of 28 days, or E capsules supplemented with P capsules for the last 14 days of E treatment. Only the E- plus P-treated monkeys exhibited an increase in serum PRL during the P treatment period. Frontal sections at the level of the optic chiasm and arcuate nucleus were examined for the colocalization of TH and PR. After E treatment, hypothalamic PR-positive cells increased in both intensity and number. Neurons expressing both TH and PR were detected in the rostral hypothalamus, lateral to the third ventricle (A11-rostral) and in a discrete subventricular population (A11-subvent). The lateral population continued caudally (A11-caudal). The A11-subvent population exhibited little steroid regulation. Of the remaining A11 TH neurons, approximately 20% exhibited PR in the spayed and E-treated groups. Addition of P doubled the percentage of PR-containing TH neurons in this group. Although very few TH-positive neurons in the ventral arcuate nucleus contained PR (A12-ventral), many double labeled neurons were observed in the dorsal arcuate region (A12-dorsal). Ventral arcuate TIDA neurons were not regulated by steroids, but E plus P increased PR expression in A12-dorsal. Double labeled cells were rarely seen in the zona incerta (A13) or the emerging ventral tegmental area (A10). In summary, P probably does not act directly on ventral arcuate TIDA neurons to stimulate PRL secretion. However, the frequency of PR-positive dopamine neurons in the A11-rostral, A11-caudal, and A12-dorsal groups increased with E and P treatment. Therefore, the contribution of the PR-positive periventricular dopamine neurons to progestin-stimulated PRL secretion may be important.

    Original languageEnglish (US)
    Pages (from-to)509-517
    Number of pages9
    JournalEndocrinology
    Volume131
    Issue number1
    StatePublished - Jul 1992

    Fingerprint

    Tyrosine 3-Monooxygenase
    Progesterone Receptors
    Haplorhini
    Steroids
    Dopaminergic Neurons
    compound A 12
    Neurons
    Capsules
    Arcuate Nucleus of Hypothalamus
    Progestins
    Peroxidase
    Lateral Hypothalamic Area
    Population
    Optic Chiasm
    Ventral Tegmental Area
    Third Ventricle
    antineoplaston A10
    Hypothalamus
    Progesterone
    Alkaline Phosphatase

    ASJC Scopus subject areas

    • Endocrinology
    • Endocrinology, Diabetes and Metabolism

    Cite this

    Immunocytochemical colocalization of hypothalamic progestin receptors and tyrosine hydroxylase in steroid-treated monkeys. / Kohama, Steven; Freesh, Francetta; Bethea, Cynthia.

    In: Endocrinology, Vol. 131, No. 1, 07.1992, p. 509-517.

    Research output: Contribution to journalArticle

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