Disturbed sleep/wake rhythms and neuronal cell loss in lateral hypothalamus and retina of mice with a spontaneous deletion in the ubiquitin carboxyl-terminal hydrolase L1 gene

Many neurodegenerative disorders including Parkinson's disease (PD) and Alzheimer's disease (AD) are associated with sleep disturbances with presumably multifactorial etiology. Ubiquitin C-terminal hydrolase L1 (UCH-L1) is involved in the pathophysiology of PD and AD. In the present study, we analyzed locomotor rhythms, orexin A-immunoreaction (Ir) in the lateral hypothalamus (LH) and melanopsin-Ir in the retina of gracile axonal dystrophy (gad) mice with a spontaneous deletion in the Uch-l1 gene. In constant darkness, gad mice showed circadian rhythms in locomotor activity, indicating the integrity of the endogenous circadian rhythm generator. However, gad mice showed an increased activity during subjective day and a decreased number of orexin A-immunoreactive neurons in the LH compared with the wild type (WT). In addition, gad mice showed increased locomotor activity in the light period when kept in a standard photoperiod and entrainment to phase shifts was significantly slower than in WT. Moreover, melanopsin-Ir was significantly reduced in the retina of gad mice, suggesting an impairment of circadian light perception in gad mice.