title: Effects of gestational and lactational exposure to low dose mercury chloride (HgCl2) on behaviour, learning and hearing thresholds in WAG/Rij rats.
abstract: We investigated the effects of inorganic mercury exposure during gestational/lactational periods on the behaviour, learning and hearing functions in a total of 32, 5-week-old and 5-month-old WAG/Rij rats (equally divided into 4 groups as 5-week and 5-month control mercury exposure groups). We evaluated the rats in terms of locomotor activity (LA), the Morris-water-maze (MWM) test and the passive avoidance (PA) test to quantify learning and memory performance; we used distortion product otoacoustic emission (DPOAE) tests to evaluate hearing ability. There were no significant differences between the 5-week-old rat groups in LA, and we detected a significant difference (p < 0.05) in the HgCl2-treated group in PA, MWM and DPOAE tests compared with the control group. The HgCl2-treated 5-week-old group exhibited worse emotional memory performance in PA, worse spatial learning and memory performances in MWM. There were no significant differences between the groups of 5-month-old rats in LA, MWM or PA. However, the DPOAE tests worsened in the mid- and high-frequency hearing thresholds. The HgCl2-treated 5-month-old group exhibited the most hearing loss of all groups. Our results convey that mercury exposure in young rats may worsen learning and memory performances as well as hearing at high-frequency levels. While there was no statistically significant difference in the behavior and learning tests in adult rats, the DPOAE test produced poorer results. Early detection of effects of mercury exposure provides medicals team with an opportunity to determinate treatment regimens and mitigate ototoxicity. DPOAE test can be used in clinical and experimental research investigating heavy metal ototoxicity.
authors.affiliation: Kocaeli University / Medical Faculty, Physiology, Kocaeli, Turkey.
authors.forename: Deniz
authors.initials: D
authors.lastname: Sahin
authors.affiliation: Kocaeli University / Medical Faculty, Kocaeli, Turkey.
authors.forename: Cem Onur
authors.initials: CO
authors.lastname: Erdolu
authors.affiliation: Kocaeli University / Medical Faculty, Physiology, Kocaeli, Turkey.
authors.forename: Sabriye
authors.initials: S
authors.lastname: Karadenizli
authors.affiliation: Sakarya University Training and Research Hospital, Otorhinolaryngology Department, Sakarya,Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Kara
authors.affiliation: Kocaeli University / Medical Faculty, Kocaeli, Turkey.
authors.forename: Gunce
authors.initials: G
authors.lastname: Bayrak
authors.affiliation: Kocaeli University / Medical Faculty, Kocaeli, Turkey.
authors.forename: Sumeyye
authors.initials: S
authors.lastname: Beyaz
authors.affiliation: Kocaeli University / Medical Faculty, Kocaeli, Turkey.
authors.forename: Buse
authors.initials: B
authors.lastname: Demir
authors.affiliation: Kocaeli University / Medical Faculty, Physiology, Kocaeli, Turkey.
authors.forename: Nurbay
authors.initials: N
authors.lastname: Ates
keywords: DPOAE test; Morris watermaze; WAG/Rij rats; hearing thresholds; inorganic mercury; passive avoidance