Inhibition of mammary gland lactose secretion by colchicine and vincristine.
The possible role of microtubules in milk production was examined in mammary gland slices from lactating guinea pigs. Colchicine, 10(-5)-10(-4) M, depressed lactose secretion within 15 min, maintaining maximal inhibition over 2.5 h, accompanied by retention of lactose within the slices. In colchicine dose-response studies (2 h, 10(-8)-10(-5) M), secretion was depressed 22% by 10(-5) M, whereas tissue lactose increased with dose up to +25% at 10(-5) M. Lactose synthesis was inhibited 3-19% without correlation to colchicine concentration. In another study, incubation with 10(-5) M lumicolchicine yielded one-third less inhibition of secretion than 10(-5) M colchicine with no increase in tissue lactose. Both drugs depressed  synthesis 31%. Lactose secretion showed a negative correlation with 10(-7)-10(-4) M vincristine yielding a maximal 66% inhibition at 10(-4) M, whereas tissue retention showed a linear increase with concentration up to 151% of control at 10(-4) M. Effects on synthesis were sporadic. These data suggest that microtubules have a role in facilitating the transport and/or secretion of lactose and perhaps other milk components.
D000818:Animals; D003078:Colchicine / Q000031:analogs & derivatives / Q000494:pharmacology*; D003571:Cytochalasin B / Q000494:pharmacology; D003864:Depression, Chemical; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007785:Lactose / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000502:physiology; D013806:Theophylline / Q000494:pharmacology; D014750:Vincristine / Q000494:pharmacology*
D003571:Cytochalasin B; D014750:Vincristine; D013806:Theophylline; D007785:Lactose; D003078:Colchicine