[Effect and mechanism of reserpine for changing salivary protein secretion in Pi-deficient rats].
OBJECTIVE
To study the effect of reserpine (RSP) for changing salivary protein secretion in Pi-deficient rats and to explore its possible mechanism.


METHODS
Twenty rats allocated in the RSP group were given subcutaneous injection of RSP [0.4 mg/(kg x d)] for 9 successive days, while the other 20 rats in the control group were injected with same volume of saline instead. On the 10th day, ten rats randomly selected from each group were subjected for extracting saliva to detect salivary amylase activity (sAA) before and after an acid stimulation; and drawing blood from the orbital vein to measure the contents of vasoactive intestinal peptide (VIP) and cyclic adenosine monophosphate (cAMP). Then they were sacrificed and their parotids were taken out for pathological examination with HE staining, as well as for VIP and cAMP measuring, and zymogen granules counting under a transmission electron microscope. The remainder animals were stopped injecting and normally fed to 40 days, then subjected to be detected as above-mentioned.


RESULTS
Food intake and body weight reduction were more significantly in the RSP group than in the control group. On the 10th day, the ratio of sAA before/after stimulation in the RSP group was 0.39 +/- 0.18, significantly lower than that in the control group (0.80 +/- 0.21, P < 0.01), but it was restored rapidly, reaching the normal range on the 25th day, on the 40th day, it became significantly different to the level on the 10th day (P < 0.05) and approached the level in the control group (P > 0.05). No significant pathological change of parotid was found in both groups; but the number of zymogen granules in the RSP group was remarkably more than that in the control group (41.4 +/- 4.9 vs 34.6 +/- 5.2, P < 0.01). Serum level of VIP in the RSP group was significantly less while that of cAMP was higher than that in the control group (22.5 +/- 13.1 mg/L vs 38.5 +/- 14.1 mg/L, and 125.8 +/- 15.5 micromol/L vs 105.3 +/- 16.7 micromol/L, both P < 0.05), but no inter-group difference was found in parotid tissue contents of both VIP and cAMP. All the indices detected became equivalent in the two groups on the 40th day.


CONCLUSIONS
The reduction of salivary protein in Pi-deficient rats induced by RSP may be related to the regulatory pathway of VIP and cAMP.
Lin
Chuan-Quan
CQ
Gastrointestinal Institute of Guangzhou University of Traditional Chinese Medicine, Guangzhou.
Chen
Yu-Long
YL
Li
Ru-Liu
RL
D000818:Animals; D000242:Cyclic AMP / Q000097:blood; D008297:Male; D008516:Medicine, Chinese Traditional; D051381:Rats; D017207:Rats, Sprague-Dawley; D012110:Reserpine / Q000009:adverse effects / Q000494:pharmacology*; D012471:Salivary Proteins and Peptides / Q000378:metabolism*; D012472:Salivation / Q000187:drug effects*; D014660:Vasoactive Intestinal Peptide / Q000097:blood
D012471:Salivary Proteins and Peptides; D014660:Vasoactive Intestinal Peptide; D012110:Reserpine; D000242:Cyclic AMP