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.

The mother's thyroid hormone status during gestation and the first few months after delivery can play a crucial role in maturation during the brain development of the child. Transient abnormalities in thyroid function at birth indicate developmental and cognitive disorders in adulthood. Choline supplementation during gestation and the perinatal period in rats causes long-lasting memory improvement in the offspring. However, it remains unclear whether choline is able to restore the deficits in rats with maternal hypothyroidism. The aim of this study was to evaluate the effects of choline supplementation on the alteration of cognitive-behavioral function, long-term potentiation (LTP), and morphological changes as well as apoptosis in pre-pubertal offspring rats. To induce hypothyroidism, 6-propyl-2-thiouracil was added to the drinking water from the 6th day of gestation to the 21st postnatal day (PND). Choline treatment was started twice a day on the first day of the gestation until PND 21 via gavage. LTP recording and Morris water maze (MWM) test were conducted at PND 28. Then, the rats were sacrificed to assess their brains. The results revealed that developmental thyroid hormone deficiency impaired spatial learning and memory and reduced LTP (both: P < 0.001). Choline treatment alleviated LTP (P < 0.001), as well as learning and memory deficits (P < 0.01) in both male and female hypothyroid rats. However, no significant changes were observed in the number of caspase-3 stained cells in choline-receiving hypothyroid groups. The results revealed that developmental thyroid hormone deficiency impaired spatial learning and memory and reduced LTP. Choline treatment alleviated LTP, as well as learning and memory deficits in both male and female hypothyroid rats.

Exercise may alleviate age-related spatial memory impairment by rescuing ß-adrenergic receptor dysregulation via both G protein-dependent and ß-arrestin-dependent mechanisms in rat hippocampus.

Hippocampal-dependent memory abilities including spatial memory decline with age. Exercise improves memory decline in aging brain, but, the precise mechanisms are still unknown. Learning and memory are recently hypothesized to be mediated by a ß-arrestin (ßArr)-dependent ß-adrenergic pathway. Hence, we examined the effect of 8 weeks of treadmill exercise on hippocampal expression of ß-adrenergic receptors (ß-ARs; members of the G protein-coupled receptor family), and ßArrs as well as spatial learning and memory in aged male rats to determine whether ß-AR/ßArr pathway could be involved in age-related memory decline. A total of 24 young (3-month-old) and aged (18-month-old) male Wistar rats were divided into young control, aged sedentary, and aged + exercise (n = 8 for each). Western blot for ß1- and ß2-ARs as well as ßArr1 and ßArr2 was performed. Spatial learning and memory were evaluated with the Morris water maze. The results showed significant up-regulation of ß1-ARs as well as significant down-regulation of ß2-AR and ßArrs (ßArr1 and ßArr2) in the hippocampus of aged rats. Spatial memory, but not spatial learning, was impaired in aging, and treadmill exercise improved it. Notably, the improvement in spatial memory was accompanied by amelioration of ß-ARs dysregulation and increase in ßArr2 levels after exercise. There was a negative association between the expression of ßArr2 and ß1-AR, but not ß2-AR, such that an increase in ßArr2 by exercise was associated with reduced ß1-AR expression, suggesting ßArr2 may contribute to posttranslational down-regulation of ß1-ARs. These data suggest that both G protein-dependent and ß-arrestin-dependent ß-AR pathways may regulate spatial learning and memory in aging brain.

Effects of choline supplementation in mothers with hypothyroidism on the brain-derived neurotrophic factor gene expression changes in pre-pubertal offspring rats.

BACKGROUND: Thyroid hormones play a vital function in the maturation in the course of mind development. Regarding the well-known effects of choline on brain-derived neurotrophic factor (BDNF), the study examined the effects of choline on hippocampal BDNF gene expression in maternal hypothyroidism rats. METHODS AND RESULTS: To induce the hypothyroidism, 6-propyl-2-thiouracil was introduced to the ingesting water from the sixth day of gestation to twenty-first postnatal day (PND). Choline-treatment started twice a day on the first day of gestation until PND 21. On PND28, pups were sacrificed. The expression of BDNF gene was evaluated after the hippocampus was harvested. Our results demonstrated that both male and female pre-pubertal offspring rats' BDNF gene expression was decreased by developmental hypothyroidism. Choline increases the ratio of relative gene expression of BDNF in the hippocampus of males and females in the control/hypothyroidism group, especially in males. CONCLUSIONS: It can be concluded that maternal choline supplementation on the first day of gestation until PND 21 improves brain development and cognitive function in pre-pubertal offspring rats regarding control/hypothyroidism groups.

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

Global rise in methamphetamine (MA) abuse during pregnancy has placed a large number of children at risk for the adverse consequences of prenatal methamphetamine exposure (PME). While behavioral and neurocognitive deficits of PME have been extensively studied in humans and adult rodents, far less is known regarding the sex- and dose-dependent effects of PME as well as the underlying mechanisms. Adolescence in nonhuman primates is also a less explored territory. In the present study, PME was inducted by oral treatment to pregnant rats on gestational days 15-19 with either low dose (0.1 mg/ml) or high dose (0.6 mg/ml) of MA. The cognitive effects of PME were then evaluated in two adolescence age-intervals: early adolescent (started on postnatal day [PND] 21) and mid-adolescent (started on PND 33), among male and female rat offspring using Morris water maze (MWM) test. Alterations in hippocampal synaptic plasticity in Schaffer collaterals-CA1 pathway were also measured in vitro. Results of behavioral test showed that PME led to serious deficits of learning and memory abilities in both male and female rat offspring. PME also depressed LTP in most of the PME subgroups. Moreover, 21-day-old rats were more sensitive to PME-induced cognitive impairment in MWM tasks, but not in hippocampal synaptic plasticity, than 33-day-old rats. No sex-dependent effects of PME were found on the cognitive function and synaptic plasticity. These findings confirmed that PME impacted negatively on cognitive performance in prepubertal male and female rats, and the impairment of hippocampal synaptic functions might partly play a significant role in these effects.

Curcumin alleviates restraint stress-induced learning and memory deficit and activity via modulation of biochemical, morphology changes, and apoptosis in the prefrontal cortex and hippocampus.

Restraint stress indicated induction of morphology, biochemistry, and behavioral impairments. Several investigations have reported that curcumin has a protective effect against stress disturbance. The present study is designed to investigate the effects of curcumin on learning and memory, activity, biochemical, morphology changes, and apoptosis in the hippocampus and prefrontal cortex of restraint stress rats. For chronic restraint stress, the rats were kept in the restrainers for 2.5 h per day for 21 consecutive days. The animals received the gavage of curcumin every other day for 21 days. After stress, the animals were subjected to behavioral tests. In restraint stress rats, locomotor activity and step-through latency were decreased using open field and shuttle box, respectively. Then, the rats were sacrificed to assess their serum and brains. A reduction was seen in the serum malonedialdehyde levels and number of neurons in the hippocampus and prefrontal cortex. The significantly decreased serum total antioxidant capacity levels and increased apoptotic cells were observed in the hippocampus and prefrontal cortex. Finally, curcumin inhibited and reversed the changes of stress induced in the prefrontal cortex and hippocampus of the rats. These findings provided evidence for the protective effect of curcumin therapy on biochemical, morphology, and behavioral changes induced by restraint stress. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Developmental effects of early-life stress on dopamine D2 receptor and proteins involved in noncanonical D2 dopamine receptor signaling pathway in the prefrontal cortex of male rats.

OBJECTIVES: Dopamine neurotransmission is implicated in multiple neuropsychiatric disorders, most strikingly in Parkinson's disease, bipolar disorder, attention-deficit hyperactivity disorder and schizophrenia. In addition to canonical pathway, D2-receptor (D2R) exerts some of its biological actions through regulating the activity of Akt and GSK3, which in turn were found to be altered in several psychiatric illnesses. The present study examined the impacts of maternal separation, an early-life stress model which has been associated with disturbed neurodevelopment and appearance of many psychiatric disorders, on developmental changes in dopamine concentration and the expression of D2Rs, Akt and GSK-3ß in the medial prefrontal cortex (PFC; a key target of stress) in adolescent and young adult male rats. METHODS: Maternal separation was performed 3 h per day from postnatal days 2 to 11. The PFC protein and dopamine contents were determined using western blotting analysis and Eliza, respectively. RESULTS: Results indicated long-term increases in the prefrontal dopamine levels in stressed adolescent and young adult male rats, accompanied by significant downregulation of D2R as well as upregulation of p-Akt and GSK-3ß contents in stressed adolescence compared to controls, with all protein levels that returned to control values in stressed adult rats. CONCLUSIONS: Our findings suggest that early-life stress differentially modulates prefrontal D2R/Akt/GSK-3ß levels during development. Since adolescence period is susceptible to the onset of specific mental illnesses, disruption of noncanonical components of D2R signaling during this critical period may have an important role in programming neurobehavioral phenotypes in adulthood and manipulations influencing Akt/GSK-3ß pathway may improve the expression of specific dopamine-related behaviors and the effects of dopaminergic drugs.

Long-Term Decreases in the Expression of Calcineurin and GABAA Receptors Induced by Early Maternal Separation Are Associated with Increased Anxiety-Like Behavior in Adult Male Rats.

INTRODUCTION: Early life stress is a well-described risk factor of anxiety disorders in adulthood. Dysfunction in GABA/glutamate receptors and their functional regulator, calcineurin, is linked to anxiety disorders. Here, we investigated the effect of early life stress, such as repeated maternal separation (MS; 3 h per day from postnatal day [P] 2 to 11), on changes in the expression of calcineurin as well as the ionotropic glutamatergic and GABAergic receptors including α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA) and GABAA receptors in the hippocampus and prefrontal cortex (PFC) of adolescent (P35) and adult (P62) male Wistar rats and their correlations with anxiety-like behavior in adulthood. METHODS: The protein levels were assessed by Western blot analysis. Anxiety-like behavior was measured in the elevated plus maze (EPM) and open field (OF) tests. RESULTS: MS induced a regional transient decrease of glutamate receptors expression at P35, with decreased NMDA and AMPA receptor levels, respectively, in the hippocampus and PFC, suggesting a possible decrease in excitatory synaptic strength. In contrast to glutamate receptors, MS had long-lasting influence on GABAA receptor and calcineurin levels, with reduced expression of GABAA receptor and calcineurin in both brain regions at P35 that continued into adulthood. These results were accompanied by increased anxiety behavior in adulthood, shown by lower percentage of number of total entries and time spent in the open arms of the EPM, and by lower time spent and number of entries in the OF central area. CONCLUSIONS: Together, our study suggests that GABAA receptors via calcineurin-dependent signaling pathways may play an important role in the expression of stress-induced anxiety-like behavior.

Negative relationship between brain α1A-AR neurotransmission and ßArr2 levels in anxious adolescent rats subjected to early life stress.

Early-life stress is correlated with the development of anxiety-related behavior in adolescence, but underlying mechanisms remain poorly known. The α1A-adrenergic receptor (AR) is linked to mood regulation and its function is assumed to be regulated by ß-arrestins (ßArrs) via desensitization and downregulation. Here, we investigated correlation between changes in α1A-AR and ßArr2 levels in the prefrontal cortex (PFC) and hippocampus of adolescent and adult male rats subjected to maternal separation (MS) and their relationship with anxiety-like behavior in adolescence. MS was performed 3 h per day from postnatal days 2-11 and anxiety-like behavior was evaluated in the elevated plus-maze and open field tests. The protein levels were examined using western blot assay. MS decreased α1A-AR expression and increased ßArr2 expression in both brain regions of adolescent rats, while induced reverse changes in adulthood. MS adolescent rats demonstrated higher anxiety-type behavior and lower activity in behavioral tests than controls. Decreased α1A-AR levels in MS adolescence strongly correlated with reduced time spent in the open field central area, consistent with increased anxiety-like behavior. An anxiety-like phenotype was mimicked by acute and chronic treatment of developing rats with prazosin, an α1A-AR antagonist, suggesting α1A-AR downregulation may facilitate anxiety behavior in MS adolescent rats. Together, our results indicate a negative correlation between α1A-AR neurotransmission and ßArr2 levels in both adults and anxious-adolescent rats and suggest that increased ßArr2 levels may contribute to posttranslational regulation of α1A-AR and modulation of anxiety-like behavior in adolescent rats. This may provide a path to develop more effective anxiolytic treatments.

Effects of treadmill exercise and sex hormones on learning, memory and hippocampal brain-derived neurotrophic factor levels in transient congenital hypothyroid rats.

Transient thyroid function abnormalities at birth exhibit intellectual developmental and cognitive disorders in adulthood. Given the well-known effects of physical activity and sex hormones on cognitive functions and brain-derived neurotrophic factor (BDNF), the present study examined the effects of treadmill exercise, sex hormones, and the combined treatment on learning and memory and hippocampal BDNF levels in transient congenital hypothyroid rats. To induce hypothyroidism, 6-propyl-2-thiouracil was added to the drinking water from the 6th day of gestation to the 21st postnatal day (PND). From PNDs 28 to 47, female and male pup rats received 17ß-estradiol and testosterone, respectively, and about 30 min later, they were forced to run on the treadmill for 30 min once a day. On PNDs 48-55, spatial learning and memory of all rats tested in the water maze, which followed by measurement of BDNF in the hippocampus. Results showed that developmental hypothyroidism induced significant deficits in spatial learning and memory and hippocampal BDNF in both male and female rats. In both male and female hypothyroid rats, exercise and exercise plus sex hormones, but not sex hormones alone alleviated learning and memory deficits and all treatments (exercise, sex hormones, and the combined treatment) increased hippocampal BDNF. These disconnects in the effects of exercise, sex hormones and the combined treatment on behavioral and neurochemical outcomes suggest that a neurochemical mechanism other than hippocampal BDNF might contribute in the ameliorating effects of exercise on learning and memory deficits induced by developmental thyroid hormone insufficiency.

The impact of sleep deprivation on sexual behaviors and FAAH expression in the prefrontal cortex of male rats.

Sleep deprivation (SD) causes alterations in the function of the endocannabinoid (EC) system and also results in alteration in many behaviors such as increased anxiety, deteriorated alertness, memory deficits, as well as sexual behaviors. Controversial data about the effects of SD on sexual response are provided. Fatty acid amide hydrolase (FAAH), the enzymes involved in the degradation of the EC system play an important role in the function of the EC system. This study aimed to investigate the effect of REM SD (RSD) and total SD (TSD) on the sexual behaviors and FAAH expression in the prefrontal cortex (PFC) of male rats. RSD was carried out through the flower pot technique for 24 h and 48 h, and TSD also was induced by keeping awake the rats by gentle handling for 6 h. Immediately after RSD and TSD, sexual behaviors were recorded for 45 min. Sexual behaviors were reduced by both types of RSD and TSD. The deleterious effects of 24 h RSD were more severe compared with 6 h of TSD. Serum testosterone concentration was significantly higher after TSD but not RSD compared to the normal sleep (NS) group. FAAH expression in the PFC was significantly reduced after both RSD and TSD compared to the NS group. Given that the function of the EC system has been previously shown to change different behaviors such as sexual activity, our results could suggest that behavioral effects of both types of SD on sexual behavior may partially result from activation of this signaling pathway by the reduction of FAAH in the PFC.

Prenatal stress increased γ2 GABAA receptor subunit gene expression in hippocampus and potentiated pentylenetetrazol-induced seizure in rats.

OBJECTIVES: Stress during pregnancy is able to bring extensive effects on neurobehavioral development in offspring. The GABAergic system plays a pivotal role in neuronal excitability, which can be affected by prenatal stress (PS). This study aimed to evaluate impact of the PS on γ2 subunit of gamma-aminobutyric acid A (GABAA) receptor gene expression in the hippocampus and seizure induced by pentylenetetrazol (PTZ) in developing rats. MATERIALS AND METHODS: In this experimental study, female Wistar rats were exposed to restraint stress during gestation and their offspring were studied on postnatal days 14 and 21 (P14 and P21, respectively) for epileptic behaviors and γ2 GABAA receptor subunit gene expression. Quantitative real-time PCR was used for evaluating the γ2 GABAA receptor subunit gene expression in rat pups. Meanwhile, PTZ was injected into the pups, and seizure behaviors were recorded for 60 min. RESULTS: The results showed that γ2 subunit mRNA expression significantly increased in the hippocampus of the stressed pups. The expression level of γ2 subunit was higher on P21 compared to that on P14 in both groups. Number of seizures with tonic-clonic features increased in pups of stressed group compared to the control group. Prenatal stress significantly caused an increase in the total score of seizure on P21. CONCLUSION: The effect of PS on seizure susceptibility is age-specific; the increased γ2 subunit level in the hippocampus might be, at least in part, the underlying mechanism for PS-induced augmentation of seizures in immature rats.

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

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 21st Postnatal Day. From Postnatal Day (PND) 28 to 47, the female and male pups received 17ß-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.

Effect of early-life inflammation and magnesium sulfate on hyperthermia-induced seizures in infant rats: Susceptibility to pentylenetetrazol-induced seizures later in life.

This study investigated the effect of inflammation and MgSO4 pretreatment on behaviors caused by hyperthermia (HT) and the effect of these interventions on PTZ-induced seizure a week later. In this experimental study, rat pups experienced inflammation on postnatal day 10 (P10). On P18-19, the pups received either saline or MgSO4 then subjected to hyperthermia. On P25-26, PTZ-induced seizure was initiated in the rats. Neonatal inflammation increased the susceptibility to HT-induced seizure. Inflammation and HT increased the susceptibility to PTZ-induced seizure. Pretreatment with MgSO4 before hyperthermia decreased the susceptibility to both HT- and PTZ-induced seizure. Furthermore, calcium and magnesium blood levels significantly decreased compared to control rats. It can be concluded that neonatal inflammation potentiates while pretreatment with MgSO4 attenuates HT-induced seizures. Also, neonatal inflammation and HT potentiate PTZ-induced seizure initiated one week later.

The effect of selective opioid receptor agonists and antagonists on epileptiform activity in morphine-dependent infant mice hippocampal slices.

Hippocampal slices of mouse brain were used to estimate how selective agonist and antagonist of opioid receptors alter Low-Mg+2 artificial cerebrospinal fluid (LM-ACSF)-induced epileptiform activities in normal and morphine-dependent mice. Brain slices were obtained from control and morphine-dependent mice. The morphine-dependent group received morphine once a day for 5 consecutive days, and the control group received saline. All injections were administered subcutaneously (s.c) in a volume of 0.1mL on postnatal days 14-18. Brain slices were perfused with LM-ACSF along with selective agonist and antagonist of µ, κ and δ opioid receptors. Changes in spike count per unit of time were used as indices to quantify the effects of LM-ACSF exposure in the slices. In both groups, DAMGO (selective µ opioid receptor agonist) and DPDPE (selective δ opioid receptor agonist) suppressed while Dyn-A (selective κ opioid receptor agonist) potentiated the epileptiform activity. Meanwhile, BFN-A (selective µ opioid receptor antagonist) recovered epileptiform activity in normal brain slices but not in morphine-dependent ones. NTI (selective δ opioid receptor antagonist) and nor-BNI (selective κ opioid receptor antagonist) decreased epileptiform activity. It seems that the excitatory effect of morphine on epileptiform activity was mediated through kappa receptors and its inhibitory effect was mediated via the mu receptor and, to a lesser degree, through the delta receptor. The pattern of effect was similar in normal and morphine-dependent slices, but the intensity of the effect was significantly stronger in normal mice. Finding of this study might be considered for further research and attention in epilepsy treatment.