Novel in vitro perfusion system for the determination of hypothalamic-pituitary-adrenal axis responses.
BACKGROUND
The hypothalamic-pituitary-adrenal (HPA) axis is a three-gland component of the endocrine system and a key modulator of the stress response. We have developed a novel in vitro perfusion system to enable the study of pharmacological and hormonal challenges to tissue components of the HPA axis. In vivo studies have shown functional sex differences (sexual diergism) in HPA responses to cholinergic drugs, and in the present in vitro study, we examine these differences at several levels of the HPA axis.


METHODS
Hypothalami, pituitaries, and adrenal glands were collected from male and female rats (n=3 per sex). One-half hypothalamus, one-half pituitary, and one adrenal gland were placed individually into three Erlenmeyer flasks connected by tubing. Flasks were perfused with medium (pH 7.4) at 37 degrees C. Sampling ports between the flasks were used to collect buffer for determination of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), and corticosterone (CORT) release from the hypothalamus, pituitary, and adrenal flasks, respectively, over an extended baseline period, to determine stability of the system, and after nicotine administration.


RESULTS
The perfusion system produced steady CRH, ACTH, and CORT baselines, the ACTH and CORT values being comparable to in vivo basal ACTH and CORT values in jugular-vein-cannulated rats. In vitro CRH, ACTH, and CORT responses to nicotine were significantly increased at 10 min and returned to baseline by 30 min, the CRH and ACTH responses from female tissues being greater than responses from male tissues. These sex differences were similar to those following nicotine administration in vivo.


CONCLUSIONS
The ability of this novel, dynamic in vitro system to replicate in vivo HPA axis responses supports its potential as a new method for pharmacological and toxicological studies.
Moidel
Melissa A
MA
Center for Neurosciences Research, Allegheny-Singer Research Institute, Allegheny General Hospital, Pittsburgh, PA 15212, USA.
Belz
Emily E
EE
Czambel
R Kenneth
RK
Rubin
Robert T
RT
Rhodes
Michael E
ME
D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000032:analysis / Q000378:metabolism; D000818:Animals; D003345:Corticosterone / Q000032:analysis / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000032:analysis / Q000378:metabolism; D005260:Female; D006863:Hydrogen-Ion Concentration; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010477:Perfusion; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D010913:Pituitary-Adrenal System / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012727:Sex Characteristics; D013268:Stimulation, Chemical; D013696:Temperature
D009538:Nicotine; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone