Early onset of aging-like changes is restricted to cognitive abilities and skin structure in Cnr1⁻/⁻ mice

Genetic deletion of the cannabinoid 1 (CB1) receptor leads to an early onset of learning and memory impairment. In the present study we asked whether the lack of CB1 receptors accelerates aging in general or is selective for cognitive functions. We therefore compared the onset and dynamics of age-dependent changes in social memory, locomotor activity, hearing ability, and in the histopathology of peripheral organs between wild-type and Cnr1 knockout (Cnr1(-/-)) mice. We observed deficits in social memory already in 3-month-old Cnr1(-/-) mice. In contrast, wild-type animals showed such deficits at the age of 6 months. Sensory and motor functions were similar between the genotypes. Thus, hearing loss for higher frequencies and the development of hypomotility showed a similar age-dependent course. In the periphery we detected an early onset of aging-like histological changes in the skin, but not in other organs. We conclude that the lack of CB1 receptor does not induce accelerated aging in general, but induces changes in cognitive function and in skin structure that resemble those associated with aging.