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

•Neonatal exposure to polymeric nanoparticle PEG-b-PLA in female Wistar rats.•Delayed effects on hypothalamic–pituitary–ovarian axis development and function were studied.•Acceleration of the puberty onset and irregular cyclicity were observed.•Pituitary hyperemia, vascular dilatation and congestion, altered pituitary LH release and increased progesterone serum levels were detected.•Possible neuroendocrine disrupting effect of PEG-b-PLA nanoparticles is proposed.

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.