EFFECT OF TREATMENT WITH THE DIHYDROPYRIDINE-TYPE CALCIUM-ANTAGONIST DARODIPINE (PY-108-068) ON THE EXPRESSION OF CALBINDIN-D-28K IMMUNOREACTIVITY IN THE CEREBELLAR CORTEX OF AGED RATS

The influence of long term treatment with the dihydropyridine-type Ca2+ antagonist darodipine (PY 108-068) on age-dependent changes in calbindin D-28K immunoreactivity in the cerebellar cortex of male Wistar rats was assessed. In 12-month-old rats used as an adult reference group, specific calbindin D-28K immunoreactivity was found within the cytoplasm of Purkinje neurons and their dendritic processes. The number of Purkinje neurons displaying calbindin D-28K immunoreactivity was decreased in the cerebellar cortex of aged in comparison with adult rats. The pattern of calbindin D-28K immunoreactivity was similar in the cerebellar cortex of 24-month-old rats (aged), although a significant decrease in the intensity of immunoreactivity was noticeable. Treatment of aged rats with darodipine for 6 months increased the percentage of immunoreactive Purkinje neurons and the intensity of calbindin D-28K immunoreactivity in the cytoplasm of Purkinje neurons. Calbindin D-28K is a Ca2+ binding protein probably involved in the modulation of Ca2+ homeostasis. The observation of a positive effect of darodipine treatment on calbindin D-28K immunoreactivity in the cerebellar cortex suggests that manipulation of dihydropyridine-type Ca2+ channels may contribute to counter age-dependent changes of Ca2+ homeostasis.