The androgen status of aging male rhesus macaques

Lawrence W. Kaler, Perry Gliessman, David L. Hess, John Hill

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    16 Scopus citations

    Abstract

    Whether the rhesus male experiences changes in the dynamics of testosterone (T) and LH secrection with age was investigated in six young (6–8 yr old; 7–12 kg) and six aged (22+ yr old; 9–11 kg) intact rhesus males. Each male was fitted with an indwelling jugular catheter, which was attached to a cranial platform and stainless steel cable tether. Catheters passed from a swivel device at the top of each cage through a wall to an adjoining room. On four occasions, 1.0-ml blood samples were obtained from each male every 20 min for 24 h for plasma T RIA and plasma LH bioassay. Plasma T and LH data were analyzed by the PULSAR program to detect hormone peaks. Mean 24-h plasma T levels were similar in young and aged males as were the pulse amplitudes of T; however, the pulsatile pattern of T concentrations was different between young and aged males. Young males displayed a marked nocturnal increase in both T concentration and number of T pulses. Aged males demonstrated a significant nocturnal elevation of plasma T concentration, but displayed a significant nocturnal diminution in both concentration and numbers of T pulses compared with young males at night. Although LH concentrations and the total number of LH pulses per 24 h were similar in young and aged males, marked age-related alterations were evident in the pulsatile pattern of LH levels. Unlike young males, aged males failed to display a daytime reduction in the number of LH pulses. Our data point to coexistent changes in hypothalamic sensitivity to the negative feedback effects of T and testicular responsiveness to LH as a function of age in the rhesus macaque.

    Original languageEnglish (US)
    Pages (from-to)566-571
    Number of pages6
    JournalEndocrinology
    Volume119
    Issue number2
    DOIs
    StatePublished - 1986

    ASJC Scopus subject areas

    • Endocrinology

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