An in vitro investigation on the effects of neonicotinoid pesticides on uterine contractility

Neonicotinoid pesticides, widely used in agriculture, are of growing concern due to possible effects on mammalian reproductive functioning. Therefore, the present study aimed to investigate the effects of widely used pesticides, acetamiprid (ACE), thiamethoxam (THX), and imidacloprid (IMA), on rat myometrial contractility. Myometrial strips were isolated from adult female Sprague Dawley rats (24 non-pregnant (diestrus), 5 pregnant (GD 19-21); 10-12 weeks old). Tissues were mounted in organ baths containing physiological saline, and isometric contractions were recorded. ACE, THX, or IMA (1, 3, 10, 30 µM) were added to the tissue bath, and their effects of spontaneous and oxytocin-induced contractions were assessed. Parameters including amplitude, frequency, and area under the curve (AUC) were analyzed at 10-min intervals. In non-pregnant rats, ACE, THX, and IMA produced a concentration-dependent reduction in spontaneous and oxytocin-induced contractions, reflected by decreases in AUC, amplitude, and frequency. In pregnant rats, no significant alterations in these parameters were observed compared with control periods. Neonicotinoids (ACE, THX, IMA) markedly attenuate myometrial contractility in non-pregnant rats but exert negligible effects in pregnant tissue. These findings indicate that uterine responsiveness to neonicotinoids is modulated by reproductive status, raising concerns not only about their potential reproductive interactions but further implications about impacting smooth muscle contraction related bodily functions.