A series of novel Dmt-Tic pharmacophoric drugs or protodrugs exhibited antagonism in vitro and in vivo using the hot-plate (supraspinal effects, the central nervous system) and tail-flick test (spinal effects). The control compounds exhibited central (CNS) mediated analgesia and were orally bioavailable opioidmimetics. Interestingly, N,N-dimethyl-Dmt-Tic-NH-adamantane and H-Dmt-Tic-NH--tert-butyl derivatives inhibited tolerance to morphine in mice, which suggests that the multidrug resistance P-glycoprotein 1 was involved due to their inhibition in vitro of Pg-1. Other Dmt-Tic compounds, such as MZ-2, in particular (patent application pending) prevents the formation of tolerance to morphine. Furthermore, the elimination of tolerance occurred without the severe side-effects seen with both naloxone and naltrexone, a FDA approved drug for the treatment of alcoholism. MZ-2 effectively and completely eliminated withdrawal symptoms and tolerance following either acute or chronic morphine addiction in mice. In addition, MZ-2 decreased food intake in ob/ob mice and diet-induced obesity mice models, altered the levels of several key indicators of obesity in the clinical analyses of blood samples. Importantly, MZ-2 elevated bone mineral density in vivo and increased the osteocalcin formation in cell cultures in vitro about 30%, whereas naltrexone was only about 17% effective;morphine decreased this phenomenon by 17%. These data suggestion the potential application of MZ-2 in fighting bother obesity and osteoporosis in human populations.
