Kr. Purushotham et al., CHOLECYSTOKININ MODULATES ISOPROTERENOL-INDUCED CHANGES IN RAT PAROTID-GLAND, Comparative biochemistry and physiology. C. Comparative pharmacologyand toxicology, 106(1), 1993, pp. 249-254
1. Parotid gland secretory function and activity of several enzymes in
volved in intracellular second messenger signalling were measured in r
ats receiving 0.5 ml i.p. injections of saline (control), isoprotereno
l, CCK or both drugs. 2. Isoproterenol caused a 2.5-fold increase in p
arotid gland wet weight compared to control. Chronic administration of
CCK alone has no effect on gland weight. A combination of CCK and iso
proterenol did not alter the hypertrophy of the gland observed with is
oproterenol alone. 3. Isoproterenol administration caused a 74% decrea
se in parotid gland amylase enzyme activity. While CCK alone did not i
nfluence the enzyme activity, it depressed amylase mRNA steady state l
evels and had an additive effect on further decreasing mRNA levels whe
n administered in combination with beta-agonist. 4. Phospholipase C re
gistered an increase ranging from 22 to 38% in all experimental groups
as compared to control. 5. Parotid gland protein kinase C and PdtIns
3-kinase activity were not altered in response to CCK alone, but in co
mbination with isoproterenol, appeared to moderate beta-agonist signal
transduction responses.