Interactive Effects of Exercise, Sex Hormones, and Transient Congenital Hypothyroidism on Long-Term Potentiation in Hippocampal Slices of Rat Offspring

Abstract

Introduction: The long-term adverse effects of transient thyroid function abnormalities at birth on intellectual development are proven. The effect of exercise increases in the presence of sex hormones. The current study aimed at investigating the possibility that a combination of sex hormones and exercise has synergistic effects on neural plasticity in Transient Congenital Hypothyroidism (TCH) rats. Methods: To induce hypothyroidism in the mothers, Propylthiouracil (PTU) was added to drinking water (100 mg/L) on the 6th day of gestation and continued until the 21 st Postnatal Day. From Postnatal Day (PND) 28 to 47, the female and male pups received 17β-estradiol and testosterone, respectively. The mild treadmill exercise began 30 minutes after the sex hormones or vehicle administration. On PND 48, electrophysiological experiments were performed on brain slices. Results: Increase of Long-Term Potentiation (LTP) was observed in sedentary-non-hormone female rats of TCH group, compared with that of the control. The exercise enhanced LTP in control rats, but the hormones showed no significant effect. The effect of exercise and sex hormone was not significant in the TCH group. The combination of exercise and testosterone enhanced LTP in TCH male rats, while the combination of exercise and estradiol or each of them individually did not produce such an effect on LTP in TCH female rats. Conclusion: The study findings showed an increase in excitatory transmission despite the returning of thyroid hormone levels to normal range in TCH female rats. Also a combination treatment including exercise and testosterone enhanced LTP in male rats of TCH group, which was a gender-specific event.

The effects of choline supplementation in mothers with hypothyroidism on the alteration of cognitive–behavioral, long‐term potentiation, morphology, and apoptosis in the hippocampus of pre‐pubertal offspring rats

“…In line with previous studies, we found that maternal hypothyroidism during pregnancy and lactation decreased learning and memory (Rashidy-Pour et al, 2020), as well as LTP (Derafshpour et al, 2019) in rat pups. In the current study, mothers treated with propylthiouracil (PTU) and their hypothyroid pups had significantly lower levels of thyroxine (T4) and higher levels of TSH than the corresponding control groups.…”

“…Pregnant rats were randomly divided into four groups for each sex: control not receiving choline (NCh/C), control receiving choline (Ch/C), hypothyroid not receiving choline (NCh/H), and hypothyroid receiving choline (Ch/H). Dams in the hypothyroid groups were administered the anti‐thyroid agent 6‐propyl‐2‐thiouracil (PTU; Sigma Co., 3050 Spruce St, St. Louis, Missouri, USA) dissolved in drinking water at a concentration of 100 ppm started on the 6th day of gestation (GD 6) and continued throughout lactation until the 21St Postnatal Day (PND 21), while the control group consumed tap water during this period (Derafshpour et al, 2019). This time frame selected for treatment was based on our recent studies, which showed the long‐term exposure of the dams to PTU, extended from early gestation to early adolescence‐induced developmental hypothyroidism in rat pups (Derafshpour et al, 2019; Rashidy‐Pour et al, 2020).…”

Effects of prenatal methamphetamine exposure on spatial cognition and hippocampal synaptic plasticity in adolescent rats

“…The slices were stored in a brain slice keeper oxygenated with 95% O 2 /5% CO 2 at the room temperature for at least 1 h before use. After recovery, a single slice was laid in the recording chamber and perfused constantly with ACSF at the rate of 2 ml/min and at 30–33°C (Derafshpour et al, 2019; Panahi et al, 2017). In the current study, one slice per rat was used and recorded successfully.…”

“…LTP was determined as the mean percentage change in fEPSP slope and PS amplitude. LTP taken during the last 10 min of each recording period after LTP induction was compared with the fEPSP slope and PS amplitude taken during the last 10 min of baseline recording (Derafshpour et al, 2019; Hosseinmardi et al, 2009).…”

Sex Hormone and Sex Hormone Receptors Modulation of Exercise-induced Neurogenesis

“…[11] Some researches contend that these sex hormone receptors can modulate neurogenesis as well [12]. Moreover, assert that "The current study aimed at investigating the possibility that a combination of sex hormones and exercise has synergistic effects on neural plasticity in Transient Congenital Hypothyroidism rats [13]." So, can sex hormones and their receptors affect exercise-induced neurogenesis?…”