EARLY INTESTINAL MICROPARTICLE UPTAKE IN THE RAT

This time-course study investigates the early uptake and passage of mi croparticles across the intestinal mucosa. Single intraoral doses of f luorescent latex particles, 1.82 mu m in diameter, were administered t o young adult male, nonfasted rats at a dose of 1.88 x 10(9) particles . Peyer's patch regions and mesenteric lymph nodes were collected at 5 , 15 and 30 min time points for both bulk tissue and morphological ana lyses. Particles were found at all experimental time points in macerat ed intestinal and nodal specimens: particle numbers were higher in pro ximal than in distal intestine at all time points despite the fact tha t particle numbers in distal Peyer's patch regions increased with time . Particle numbers in mesenteric lymph nodes also increased with time after administration. Detailed morphological data for several intestin al and nodal tissue compartments showed substantial early uptake of pa rticles by villous epithelium, including goblet cells, but low involve ment of follicle-associated cells. The distribution of particles in th e lymph nodes confirmed that translocation occurred to all nodal compa rtments. These studies give confirmatory evidence that uptake and tran slocation of microparticles may take place as early as 5 min after adm inistration and suggest that intestinal region may influence uptake.