Altered age-dependent modulation of tissue renin messenger RNA levels in the spontaneously hypertensive rat.
OBJECTIVE
To evaluate the possible role of tissue renin overproduction in the pathogenesis and time course of hypertension development in the spontaneously hypertensive rat (SHR) of the Okamoto strain by measuring tissue renin gene expression at different stages of hypertension development.


METHODS
Measurements of kidney, adrenal gland and brain stem renin messenger RNA (mRNA) levels were performed in SHR aged 4, 12, 20 and 36 weeks and in age-matched normotensive Wistar-Kyoto (WKY) rats.


METHODS
A fully quantitative, competitive reverse transcriptase polymerase chain reaction method was used to measure tissue renin mRNA levels. Plasma renin concentrations were measured by radioimmunoassay.


RESULTS
Compared with age-matched WKY rats, renin mRNA levels in the adrenal gland of SHR were significantly higher at ages 4, 12 and 36 weeks. Brain stem renin mRNA levels were significantly higher in SHR than in WKY rats at ages 4, 12 and 20 weeks. In contrast, renal renin mRNA levels were consistently lower in SHR at all ages, as were plasma renin concentrations.


CONCLUSIONS
The present study indicates an important role for renin gene expression both in adrenal and in brain stem tissues in the pathogenesis of hypertension in SHR. Adrenal and brain renin-angiotensin systems may interact with each other synergistically in the development and maintenance of hypertension in SHR. Suppressed renal renin gene expression could then be an indirect consequence of the amplified renin-angiotensin system in the adrenal gland and in the brain or a baroreceptor-mediated consequence of its hypertension.
Yu
H
H
Department of Physiology, University of Melbourne, Victoria, Australia.
Di Nicolantonio
R
R
D000311:Adrenal Glands / Q000378:metabolism; D000367:Age Factors; D000818:Animals; D001483:Base Sequence; D001933:Brain Stem / Q000378:metabolism; D006973:Hypertension / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism; D008297:Male; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012083:Renin / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics; D012084:Renin-Angiotensin System / Q000502:physiology; D017384:Sequence Deletion
D012333:RNA, Messenger; D012083:Renin