Effects of crocin on locomotor activity as well as novel object recognition and object location memories in chronic restraint stressed rats

Introduction: Chronic stress impairs memory and certain brain functions such as locomotor activity. Crocin is one of the active components of saffron and has neuroprotective effects on brain functions. This study investigated crocin effects on locomotor activity and recognition of new conditions (exploration time) as well as novel object recognition and object location memories in chronic restraint stress rats. Methods: Thirty-two male Wistar rats were randomly allocated to control group, restraint stress group (6h/day for 21days) and two groups receiving daily intraperitoneal injections of crocin (30 and 60mg/kg) accompanied by restraint stress. Memories were evaluated using the relevant novel object recognition (NOR) and object location (OLT) tests. Results: The NOR and OLT results, respectively, revealed significant and non-significant decreases in locomotor activity in the stressed group. The NOR results revealed enhanced locomotor activity due to crocin administration (30 and 60mg/kg). The NOR revealed significant enhancements in recognizing new conditions in both crocin treatments while the OLT test did so only with a crocin dose of 60mg/kg. Restraint stress and crocin treatments led to no significant differences in novel object recognition and object location memories. Finally, the stressed group exhibited significant increases in serum corticosterone levels but corticosterone levels declined significantly with crocin dose of 30mg/kg. Conclusion: The high and low doses of crocin had different effects on the NOR and OLT variables under restraint stress conditions. The NOR test as cognitive test was found more sensitive to crocin treatments than the OLT test as spatial test although neither the memories showed changes in response to such treatment.