A simple method for the specific detection of Ren-1 renin.
BACKGROUND
Ren-1 and Ren-2 renin are expressed in the kidneys of all mice and in the submandibular gland of several mouse strains. The present study determined the usefulness of modified periodic acid silver-methenamine (PAM) staining for the specific detection of Ren-1 renin.


METHODS
Conventional paraffin sections were prepared from kidneys of ICR, BALB/cA, C57BL/6Cr, C3H/HeN, DBA/2Cr, angiotensin II type 1a receptor gene knockout (AT1aKO) mice, Wistar rats and a human, and submandibular glands of C57BL/6Cr and DBA/2Cr mice. Sections were analyzed for the presence of renin using PAM and immunohistochemistry. PAM reactions were terminated at generally or weakly intense (weak PAM staining; W-PAM). In addition, kidneys of DBA/2Cr mice were fixed using various fixatives (formalin, PFA, PLP, Zamboni's, Bouin's, or Carnoy's) and treated using identical procedures.


RESULTS
Although PAM-positive reactions were observed in juxtaglomerular (JG) cells, W-PAM reactions were particularly specific for these cells. These findings were observed in all mouse strains. Immunohistochemistry using mirror sections suggested that a W-PAM-positive reaction detected renin. This hypothesis was confirmed by the results from AT1aKO mice. Briefly, W-PAM detected an expansion of renin-positive areas in AT1aKO mice. Rat and human kidneys and mouse submandibular glands were negative for W-PAM. Levels of JG cell detection by W-PAM were similar in samples fixed in formalin, PFA, PLP, or Zamboni's.


CONCLUSIONS
The present findings show that W-PAM can identify Ren-1 renin, but not Ren-2, rat or human renin. The W-PAM method is useful for the specific detection of Ren-1 renin.
Yabuki
Akira
A
Department of Veterinary Anatomy, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan. yabu@vet.agri.kagoshima-u.ac.jp
Suzuki
Syusaku
S
Matsumoto
Mitsuharu
M
Taniguchi
Kazuyuki
K
Nishinakagawa
Hayao
H
D000818:Animals; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007668:Kidney / Q000737:chemistry*; D008297:Male; D008709:Methenamine; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008813:Mice, Inbred ICR; D010504:Periodic Acid; D051381:Rats; D017208:Rats, Wistar; D012083:Renin / Q000032:analysis*; D012834:Silver; D013194:Staining and Labeling / Q000379:methods*
D010504:Periodic Acid; D012834:Silver; D012083:Renin; D008709:Methenamine