AJP - Endocrinology and Metabolism, Vol 249, Issue 4 385-E391, Copyright © 1985 by American Physiological Society
Metabolic changes during maturation of male monkeys: possible signals for onset of puberty
J. L. Cameron, D. J. Koerker and R. A. Steiner
There is a close relationship between the metabolic status of a maturing
animal and the timing of puberty onset. However, the signals linking
metabolic status to the maturation of the reproductive axis remain unknown.
We looked for metabolic differences before and after puberty by comparing
plasma profiles of insulin, glucose, amino acids, beta-hydroxybutyrate, and
glycerol between juvenile and adult monkeys in fed and fasted states.
Thirteen juvenile and 13 adult male crab-eating macaques (Macaca
fascicularis) were fed a mixed meal, and blood samples were collected at
intervals between 1.5 and 52 h after the meal. Plasma insulin
concentrations decreased in a similar manner in both groups during the
first 16 h of fasting. By 20 h after a meal, basal insulin levels were
significantly lower (P less than 0.025) in juveniles compared with adults
and remained so until the end of the fast. Circulating levels of glucose
were similar in juveniles and adults immediately after a meal and then
decreased significantly (P less than 0.025) in juveniles by 28 h of fasting
and in adults by 52 h of fasting. Plasma concentrations of all large
neutral amino acids (i.e., tyrosine, tryptophan, phenylalanine, valine,
leucine, and isoleucine, LNAA) except tryptophan decreased more
precipitously in juveniles than in adults during the first 20 h of fasting.
However, the ratios of tyrosine to other LNAA and tryptophan to other LNAA
were similar in juveniles and adults at all times. beta-Hydroxybutyrate
concentrations were low in both groups until 24 h after a meal, at which
time plasma levels increased more rapidly and attained higher values in
juveniles compared with adults.(ABSTRACT TRUNCATED AT 250 WORDS)
