Spontaneously hypertensive rats are the most common animal
model used to study attention deficit hyperactivity disorder
(ADHD). The present study investigated the levels of steroid
hormones in the bloodstream of hypertensive rats and its
normotensive control strain, Wistar-Kyoto rats, to check if there
are any hormonal differences between both strains at the onset
of ADHD. Plasma samples were collected from young (5-weekold) and mature (10-week-old) male hypertensive and
normotensive rats to determine the serum level of testosterone,
17β-estradiol, free estriol, progesterone, corticosterone and
cortisol using ELISA kits. The results showed statistically
significant increases in serum levels of testosterone and free
estriol in 10-week-old hypertensive and normotensive rats when
compared to 5-week-old animals. Moreover, the concentrations
of progesterone, corticosterone and cortisol were significantly
elevated in 10-week-old hypertensive rats when compared to
5-week-old animals of both strains as well as 10-week-old
normotensive rats. Hormonal differences observed between
10-week-old hypertensive and normotensive rats were also
accompanied by differences in the volumes of lateral ventricles as
well as the third ventricle and cerebral aqueduct. In conclusion,
elevated contents of progesterone, corticosterone and cortisol in
hypertensive rats may be associated not only with ADHD but also
with developing hypertension. This question needs further study.