Expression of the micro-opioid receptor on Malassezia pachydermatis and its effect in modulating phospholipase production

Malassezia spp. may act as opportunistic skin pathogens in humans and animals. Malassezia pachydermatis proliferation and phospholipase production may play a pathogenic role in the occurrence of skin lesions in dogs. This study investigates the presence of mu-opioid receptor (MOR) in M. pachydermatis strains isolated from healthy dogs and dogs with skin lesions and its effects on phospholipase activity (p.a.). P.a. of 64 M. pachydermatis isolates was evaluated using different concentrations of naloxone (Nx), a MOR antagonist. Isolates were divided into Group A (i.e., 40 isolates from 26 dogs with dermatitis) and Group B (i.e., 24 isolates from 12 healthy dogs). The MOR expression was analyzed by Western blot and immunofluorescence. A statistically higher p.a. than that of the controls was found with isolates in Group A at a Nx concentration of 10(-6) M (P