Oral quetiapine treatment results in time-dependent alterations of recognition memory and brain-derived neurotrophic factor-related signaling molecules in the hippocampus of rats

Antipsychotic drugs (APDs) have a variety of important therapeutic applications for neuropsychiatric disorders. However, they are routinely prescribed off-label across all age categories, a controversial practice given their potential for producing metabolic and extrapyramidal side effects. Evidence also suggests that chronic treatment with some APDs may lead to impairments in cognition and decreases in brain volume, although these findings are controversial. The purpose of the studies described here was to evaluate one of the most commonly prescribed APDs, quetiapine, for chronic effects on recognition memory, brain-derived neurotrophic factor (BDNF), its precursor proBDNF, as well as relevant downstream signaling molecules that are known to influence neuronal plasticity and cognition. Multiple cohorts of adult rats were treated with quetiapine (25.0 mg/kg/day) for 30 or 90 days in their drinking water then evaluated for drug effects on motor function in a catalepsy assessment, recognition memory in a spontaneous novel object recognition (NOR) task, and BDNF-related signaling molecules in the post mortem hippocampus via Western Blot. The results indicated that oral quetiapine at a dose that did not induce catalepsy, led to time-dependent impairments in NOR performance, increases in the proBDNF/BDNF ratio, and decreases in Akt and CREB phosphorylation in the hippocampus. These results indicate that chronic treatment with quetiapine has the potential to adversely affect recognition memory and neurotrophin-related signaling molecules that support synaptic plasticity and cognitive function. Given the widespread use this APD across multiple conditions and patient populations, such long-term effects observed in animals should be considered.