Carasso (1987) the effects of dsip on pain threshold during light and dark periods in rats are not naloxone sensitive, international journal of neuroscience, 37 : 1 2, 85 88, doi : 10. Melanotan ii works by mimicking the body’s natural alpha melanocyte stimulating hormone (α msh), which activates melanocortin receptors, especially mc1r, to increase melanin production in the skin. lyophilized powder.