Delayed adverse effects of neonatal exposure to polymeric nanoparticle poly(ethylene glycol)-block-polylactide methyl ether on hypothalamic-pituitary-ovarian axis development and function in Wistar rats.

Abstract We studied delayed effects of neonatal exposure to polymeric nanoparticle poly(ethylene glycol)- block -polylactide methyl ether (PEG- b -PLA) on the endpoints related to pubertal development and reproductive function in female Wistar rats from postnatal day 4 (PND4) to PND 176. Female pups were injected intraperitoneally, daily, from PND4 to PND7 with PEG- b -PLA (20 or 40 mg/kg b.w.). Both doses of PEG- b -PLA accelerated the onset of vaginal opening compared with the control group. In the low-dose PEG- b -PLA-treated group, a significantly reduced number of regular estrous cycles, increased pituitary weight due to hyperemia, vascular dilatation and congestion, altered course of hypothalamic gonadotropin-releasing hormone-stimulated luteinizing hormone secretion, and increased progesterone serum levels were observed. The obtained data indicate that neonatal exposure to PEG- b -PLA might affect the development and function of hypothalamic–pituitary–ovarian axis (HPO), and thereby alter functions of the reproductive system in adult female rats. Our study indicates a possible neuroendocrine disrupting effect of PEG- b -PLA nanoparticles.