Homeostatic thymus hormone stimulates corticosterone secretion in a dose- and age-dependent manner in rats.
There is increasing evidence that the neuroendocrine system is responsive to hormonal signals generated by the immune systems. In particular, interleukin-1 and thymosin have been shown to stimulate the pituitary-adrenal axis in young animals. We report here that homeostatic thymus hormone (HTH), a well-characterized thymic preparation, increases plasma levels of corticosterone but not prolactin (PRL) in a dose- and age-dependent manner in male Sprague-Dawley rats. Young (3 months) and old (26 months) conscious, free-moving animals carrying an indwelling atrial cannula received the substances to be tested via the cannulas. Plasma samples were taken every 30 min for 5 h and hormones were measured by radioimmunoassay. HTH doses of 1 and 8 mg/kg body weight injected into young rats elicited a 7.8- and 12.8-fold increase in plasma corticosterone, respectively, as compared to saline-injected controls. The HTH-induced peak corticosterone levels were reached within 1.5 and 2.5 h after HTH injection. Plasma PRL was not affected by HTH in either age group. A single dose of 8 mg HTH/kg body weight induced a smaller corticosterone response in old than in young rats, although the time course of the response was similar in both age groups. The present results further suggest the existence of a lymphoid-neuroendocrine axis in young animals. The data also suggest that a disruption in immune-endocrine integration occurs during aging in rats.
Goya
R G
RG
Department of Physiology, Michigan State University, East Lansing.
Sosa
Y E
YE
Quigley
K L
KL
Reichhart
R
R
Meites
J
J
D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D003345:Corticosterone / Q000097:blood / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D008297:Male; D011388:Prolactin / Q000097:blood; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013951:Thymus Hormones / Q000494:pharmacology*
D013951:Thymus Hormones; D011388:Prolactin; D003345:Corticosterone