Effect of short- and long-term administration of caffeine on salivary flow rate, amylase, IgA and C-reactive protein in male Wistar rats
Keywords:Caffeine, Salivation, Immunoglobulin A, C-Reactive Protein, Rat
Background: Despite several reports on the effects of caffeine on various body systems, those on short- and long-term effect on salivary secretion are lacking. Aim: To evaluate the short- and long-term effect of caffeine on salivary secretion in rats.
Methods: Seventy-two male Wistar rats (110 - 150 g), randomly divided into two main groups (subdivided into 6 groups of 6 animals) were included. The short- and long-term groups were given different doses (3 - 40 mg/kg bw) of caffeine for 7 days and 28 days respectively. After treatments, stimulated saliva samples were collected and assessed for lag-time, flow rate, alpha amylase activity, secretory immunoglobulin A (IgA) and C reactive protein (CRP) concentrations. Results: Salivary lag-time was significantly lower in the 20 mg/kg and 40 mg/kg groups only compared to the control group (p < 0.001 for both) after short-term caffeine administration. Also, salivary amylase activity was significantly higher in the 40 mg/kg groups compared to the control group (p = 0.01) after short-term caffeine administration. Salivary flow rate was significantly lower in the 40 mg/kg group compared to the control group (p < 0.01) following long-term caffeine administration. No changes were observed in the levels of salivary IgA and CRP for both short- and long-term administration of the different doses of caffeine. Conclusion: Whereas short-term caffeine administration was associated with lower salivary lag-time and higher salivary amylase activity also at high doses, long-term caffeine administration was associated with reduced salivary flow rate at high dose only.