Change of expression of renal alpha1-adrenergic receptor and angiotensin II receptor subtypes with aging in rats.
OBJECTIVE
It has been considered that the functional decline of renal vasoconstriction during senescence is associated with an alteration in renal alpha1-adrenergic receptor (alpha1-AR) expression. While alterations in renal angiotensin II receptor (ATR) expression was considered to have an effect on renal structure and function, until now little information has been available concerning alpha1-AR and ATR expression variations over the entire aging continuum. The present study was undertaken to examine the expression levels of alpha1-AR and ATR subtypes in renal tissue during the spectrum running from young adulthood, to middle age, to the presenium, and to the senium.


METHODS
Semiquantitative Reverse Transcription Polymerase Chain Reaction (RT-PCR) and Western Blot were used to quantify the messenger RNA (mRNA) and protein levels of alpha1-AR and ATR subtypes in renal tissue in 3-month-old (young adult), 12-month-old (middle age), 18-month-old (presenium) and 24-month-old (senium) Wistar rats.


RESULTS
alpha1A-AR expression decreased gradually with aging: it was decreased during middle age, the presenium and the senium, compared, respectively, with young adult values (p<0.01), and there was a significant decline both in the presenium with respect to middle age and in the senium with respect to the presenium. alpha1B-AR and alpha1D-AR expression were unmodified during senescence. AT1R expression was unaffected by aging during young adulthood and middle age, but exhibited a remarkable downregulation in the presenium and senium periods (p<0.01). AT2R expression was markedly increased in the senium (p<0.01).


CONCLUSIONS
These results suggest that there are considerable variations in the expression levels of renal alpha1-AR and ATR subtypes during aging. alpha1A-AR expression downregulation may account for the reduced reactivity of renal alpha1-AR to vasoconstrictors and to renal function decline in the senium. Both the downregulation of AT1R and the upregulation of AT2R may be influential in maintaining normal physiological renal function during aging.
Li
Yan-Fang
YF
The Department of Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China. liyf101@sohu.com
Cao
Xiao-Jing
XJ
Bai
Xue-Yuan
XY
Lin
Shu-Peng
SP
Shi
Shu-Tian
ST
D000375:Aging / Q000235:genetics / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D018507:Gene Expression Regulation, Developmental; D007668:Kidney / Q000254:growth & development / Q000502:physiology; D008297:Male; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar / Q000254:growth & development; D018340:Receptors, Adrenergic, alpha-1 / Q000235:genetics*; D011945:Receptors, Angiotensin / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D012333:RNA, Messenger; D018340:Receptors, Adrenergic, alpha-1; D011945:Receptors, Angiotensin