Aging Impairs Release of Central and Peripheral Cholecystokinin (CCK) in Male But Not in Female Rats

BACKGROUND: Cholecystokinin (CCK) is an important bioactive peptide which stimulates pancreatic enzyme secretion and is also a neuromodulator in the central nervous system. We examined whether CCK release from the central and peripheral tissues was decreased in old animals, and whether there were sex-related differences. METHODS: Young (5-10-month-old) and old (25-29-month-old) male and female Wistar rats were used. Synaptosomes were prepared from the cerebral cortex, and the vascularly perfused duodenojejunum was isolated to examine central and peripheral CCK release, respectively. In some young female rats, 21 days after bilateral ovariectomy, the peripheral CCK release and the changes in CCK mRNA levels were examined. RESULTS: The central CCK release was impaired in response to the higher concentration of KCl, and the peripheral CCK response to the highest dose of neuromedin C was impaired in old male rats. However, no aging effect was observed in female rats, and ovariectomy did not affect CCK release or CCK mRNA level. CONCLUSIONS: CCK release from both central and peripheral tissues was decreased in old male rats, but not in old female rats.