Effect of nanoparticle-rich diesel exhaust on testicular and hippocampus steroidogenesis in male rats.
BACKGROUND
Nanoparticle-rich diesel exhaust (NR-DE) has potentially adverse effects on testicular steroidogenesis. However, it is unclear whether NR-DE influences steroidogenic systems in the brain.


OBJECTIVE
To investigate the effect of NR-DE on hippocampal steroidogenesis of adult male rats in comparison with its effect on the testis.


METHODS
F344 male rats (8-week-old) were randomly divided into four groups (n = 8 or 9 per group) and exposed to clean air with 4.6 ± 3.2 μg/m(3) in mass concentration, NR-DE with 38 ± 3 μg/m(3) (a level nearly equivalent to the environmental standard in Japan (low NR-DE)), NR-DE with 149 ± 8 μg/m(3) (high NR-DE), or filtered diesel exhaust with 3.1 ± 1.9 μg/m(3) (F-DE), for 5 hours/day, 5 days/week, for 1, 2 or 3 months. F-DE was prepared by removing only particulate matters from high NR-DE with an HEPA filter.


RESULTS
Exposures to the high NR-DE for 1 month, and low NR-DE for 2 months, significantly increased or tended to increase plasma and testicular testosterone levels compared to clean air exposure, which might have resulted from the increased expression of mRNA of steroidogenic acute regulatory protein and its protein in the testes of rats. In the hippocampus, high NR-DE exposure for 1 month significantly increased the androstendione level compared to the clean air exposure, while no significant difference was observed in the steroidogenesis between fresh air exposure and any exposure to NR-DE or F-DE.


CONCLUSIONS
NR-DE may influence steroidogenic enzymes in the testis, but not those in the hippocampus.
Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Japan.
Nozomi
N
Yamagishi
Yuki
Y
Ito
Doni Hikmat
DH
Ramdhan
Yukie
Y
Yanagiba
Yumi
Y
Hayashi
Dong
D
Wang
Chun Mei
CM
Li
Shinji
S
Taneda
Akira K
AK
Suzuki
Kazuyoshi
K
Taya
Gen
G
Watanabe
Michihiro
M
Kamijima
Tamie
T
Nakajima
D000393:Air Pollutants / Q000737:chemistry / Q000633:toxicity*; D000818:Animals; D015153:Blotting, Western; D002853:Chromatography, Liquid; D003627:Data Interpretation, Statistical; D012739:Gonadal Steroid Hormones / Q000096:biosynthesis* / Q000097:blood; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D019570:Inhalation Exposure; D007986:Luteinizing Hormone / Q000096:biosynthesis / Q000097:blood; D008297:Male; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D051381:Rats; D011916:Rats, Inbred F344; D060888:Real-Time Polymerase Chain Reaction; D053719:Tandem Mass Spectrometry; D013737:Testis / Q000187:drug effects* / Q000378:metabolism; D001335:Vehicle Emissions / Q000032:analysis / Q000633:toxicity*
D000393:Air Pollutants; D012739:Gonadal Steroid Hormones; D001335:Vehicle Emissions; D007986:Luteinizing Hormone