New generation prostate cancer therapy may impact motivation for
exploration, spatial learning and dopaminergic transmission in aged
castrated mice
Abstract
Background and Purpose: Cognitive side effects after cancer treatment
threatening quality of life (QoL) constitute a major challenge in
oncology. Abiraterone acetate plus prednisone (AAP) and enzalutamide
(ENZ) are next generation therapy (NGT) administered with androgen
deprivation therapy to metastatic castration-resistant prostate cancer
(mCRPC) patients. NGT significantly improved mCRPC overall survival but
neurological side effects such as fatigue and cognitive impairment have
been recently reported. Experimental Approach: We developed a behavioral
17 months-aged and castrated mouse model receiving per os AAP or ENZ
during 5 days per week for six consecutive weeks. After behavioral
tests, brain and plasma were collected for immunohistochemical studies.
Spontaneous activity, cognitive functions and emotional reactivity, as
well as neurobiological functions were investigated. Key Results: ENZ
exposure reduced spontaneous activity and exploratory behavior
associated with a decreased tyrosine hydroxylase (TH)-dopaminergic
activity in the substantia nigra pars compacta and the ventral tegmental
area. A decrease in TH+-DA afferent fibers and Phospho-DARPP32-related
dopaminergic neuronal activities in the striatum and the ventral
hippocampus, highlighted ENZ-induced dopaminergic regulation whithin the
nigrostriatal and mesolimbocortical pathways. ENZ and AAP treatments did
not substantially modify spatial learning and memory or behavioral
flexibility performances, but ENZ led to a thygmotaxis behavior
impacting the cognitive score, and reduced c-fos-related activity of
NeuN+-neurons in the dorsal hippocampus. Conclusion and Implications:
These results establish the consequences of the mCRPC treatment ENZ in
aged castrated mouse motivation to exploration and cognition, of
particular importance for future management of patients elderly postrate
cancer patients and their QoL.