Pre- and postnatal exposure to ambient levels of urban particulate matter (PM_2.5) affects mice spermatogenesis

Abstract

This work characterizes the effects of ambient levels of urban particulate matter (PM_2.5) from the city of Sao Paulo on spermatogenesis using mice exposed during the embryo–fetal and/or postnatal phases of development. Parental generations (BALB/c mice) were exposed to air pollution in chambers with or without filtering PM_2.5 for 4 months. Animals were mated, and half of the 1-day-old offspring were moved between chambers, which yielded prenatal and postnatal groups. Remaining offspring comprised the non-exposed and pre+postnatal exposed groups. After 90 days, the animals were sacrificed for testis collection and weighing. Optical microscopy was used for the morphometric analyses of the cell counts, spermatogenic cycle, proliferation, and apoptosis. Prenatally exposed animals presented reduced body and testicular weight with an increased gonadosomatic index (GSI). Testicular volume also decreased, as well as the tubular diameter in testes of the same animals. Proliferation, apoptosis, and spermatogenic cycle analyses showed no significant differences among groups. However, the tubules at stage VII of pre- and postnatal animals presented a reduced number of elongated spermatids. Pre+postnatal group presented higher spermatid head retention at stages VIII–XII. These results show that ambient levels of PM_2.5 from Sao Paulo city affect spermatogenesis by damaging sperm production.

Keywords::

• Spermatogenesis
• urban air pollution
• ambient levels of PM2.5
• proliferation
• apoptosis
• spermatid retention
• spermatogenic cycle

Acknowledgements

This work was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP-2003/10772-9), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), and Fundação Faculdade de Medicina (FFM). The authors wish to thank Angela Batista Gomes dos Santos, Maria Cristina Rodrigues Medeiros, Andressa Brito, Amanda Vasconcelos, Rodolfo de Paula Vieira Ph.D., Ana Júlia F.C. Lichtenfels Ph.D., and Regiani Carvalho-Oliveira Ph.D. for technical and scientific assistance.

Declaration of interest

The authors report no declaration of interest.