The Small Molecule DDOX Confers Neuroprotection and Alleviates Motor Deficits in a Preclinical Rat Model of...

Tetracycline-derived compounds with anti-inflammatory properties have demonstrated neuroprotective potential in preclinical models of Parkinson's disease. In this study, we investigated the efficacy of DDOX (4-dedimethylamino 12a-deoxydoxycycline), a novel non-antibiotic tetracycline derivative. We used an intrastriatal unilateral 6-hydroxydopamine (6-OHDA) lesion paradigm in rats, which leads to partial nigrostriatal dopaminergic denervation. Our goal was to assess whether DDOX could preserve nigrostriatal dopaminergic integrity, reduce lesion-associated glial responses in the striatum, and improve motor function. Daily administration of DDOX (20 mg/kg, subcutaneously), beginning five days prior to lesion and continuing for fifteen days post-lesion, significantly attenuated the loss of dopaminergic terminals in the dorsal striatum and that of dopaminergic cell bodies in the ventral substantia nigra, as indicated by tyrosine hydroxylase (TH) immunostaining analysis. DDOX also markedly suppressed lesion-induced glial responses in the striatum. Behavioral assessments revealed that DDOX preserved motor performance, as evidenced by improved forelimb use (stepping test), maintained coordination and balance (rotarod), and maintained spontaneous locomotion (open field - actimeter). Additionally, DDOX significantly diminished amphetamine-induced rotational asymmetry, suggesting preservation of dopaminergic tone. Notably, the extent of functional recovery exceeded the degree of TH-immunoreactive nerve terminal preservation, indicating that DDOX's benefits may extend beyond dopaminergic neuroprotection. Further studies are warranted to elucidate the underlying mechanisms of these effects and confirm DDOX's efficacy in other Parkinson's disease models.