Effects of biotin deficiency on short term memory: The role of glutamate, glutamic acid, dopamine and protein kinase A.

Insufficient dietary biotin intake, biotinidase deficiency, drug-biotin interactions can cause biotin deficiency which may result in central nervous system dysfunctions. We hypothesized that biotin deficiency could disrupt learning and memory functions by altering glutamate, glutamine, dopamine levels and protein kinase A (PKA) activity in the hippocampus. Sixteen female and 4 male Wistar rats were mated and females were separated into 4 groups. Three pups were selected from each mother and a total of 48 pups were divided into the following experimental groups. NN group, normal diet in the prenatal and postnatal period. NB group, normal diet in the prenatal and a biotin-deficient diet in the postnatal period. BN group: biotin-deficient diet in the prenatal and a normal diet in the postnatal period, BB group: biotin-deficient diet in both the prenatal and postnatal period. Open Field, Y-Maze, Object Location, and Novel Object Recognition Tests were performed in all groups and rats were sacrificed. Glutamine, glutamate, dopamine levels and PKA activity were analyzed in the hippocampi. In the open field test, distance and velocity values of NB, BN and BB groups were decreased with respect to the NN group. Learning and memory functions of NB, BN and BB groups were found to be impaired in behavioral tests. Dopamine levels and PKA activity were also decreased in all rat pups fed with a biotin deficient diet. In conclusion, we demonstrated that biotin deficiency deteriorates short-term memory and locomotor activity. This impairment may relate to decreased dopamine levels and PKA activity in the hippocampus.

Does Resveratrol Prevent Sevoflurane Toxicity in Newborn Rats?

Inhalation anesthetics have been shown to cause neurodevelopmental disorders and neurotoxic effects. In this study, we aimed to investigate the effect of resveratrol on the possible neurotoxic effect of sevoflurane and the brain-derived neurotrophic factor (BDNF) pathway in newborn rats. The animals were divided into four groups: control, sevoflurane, sevoflurane+resveratrol 25 mg/kg, and sevoflurane+resveratrol 50 mg/kg. The groups that received anesthesia were given 3% sevoflurane for 2 h on the postnatal seventh, eighth, and ninth days. Control gas was applied to the control group. The Morris water maze (MWM) test was performed on postnatal 35th day. After performing the open field test on the postnatal 41st day, the animals were dissected, and the hippocampal BDNF levels were determined by Western blot method. In the MWM test, there was a significant decrease in the time spent in the target quadrant in the sevoflurane anesthesia group compared with control group. This reduction was reversed with the resveratrol pretreatment. Sevoflurane exposure significantly decreased hippocampal BDNF levels compared with the control group. The resveratrol 25 mg/kg pretreatment did not reverse this reduction, whereas resveratrol 50 mg/kg ameliorated this impairment. Sevoflurane did not cause any significant difference in the rats' performance in the open field test. However, 50 mg/kg resveratrol pretreatment caused a statistically significant increase in this performance. Our results showed that sevoflurane impaired learning and memory functions in newborn rats and resveratrol reversed this deterioration. Also BDNF might play a role in this beneficial effect of resveratrol.

Effects of adropin on learning and memory in rats tested in the Morris water maze.

Adropin is a secreted peptide, which is composed of 43 amino acids and shows an effective role in regulating energy metabolism and insulin resistance. Motor coordination and locomotor activity were improved by adropin in the cerebellum. However, it is not known whether adropin administration has an effect on spatial learning and memory. In this study, we investigated the effect of adropin on spatial learning and memory and characterized the biochemical properties of adropin in the hippocampus. Thirty male Sprague-Dawley rats were randomly divided into two groups as control and adropin groups. The control group received 0.9% NaCl intracerebroventricular for 6 days, while the adropin groups received 1 nmol of adropin dissolved in 0.9% NaCl (for 6 days). The Morris water maze, Y maze, and object location recognition tests were performed to evaluate learning and memory. Also, the locomotor activity tests were measured to assess the motor function. The expression of Akt, phospho-Akt, CREB, phospho-CREB, Erk1/2, phospho-Erk1/2, glycogen synthase kinase 3 ß (GSK3ß), phospho-GSK3ß, brain-derived neurotrophic factor (BDNF), and N-methyl-d-aspartate receptor NR2B subunit were determined in the hippocampal tissues by using western blot. Behavior tests showed that adropin significantly increase spatial memory performance. Meanwhile, the western blot analyses revealed that the phosphorylated form of the Akt and CREB were enhanced with adropin administration in the hippocampus. Also, the expression of BDNF showed an enhancement in adropin group in comparison to the control group. In conclusion, we have shown for the first time that adropin exerts its enhancing effect on spatial memory capacity through Akt/CREB/BDNF signaling pathways.

The Short-Term Effect of Occupational Levels of 50 Hz Electromagnetic Field on Human Heart Rate Variability.

Previous studies have indicated that there is no consensus on the effects of extremely low-frequency electromagnetic (ELF-EMF) exposure on the cardiovascular system. This study aimed to explore the short-term effect of ELF-EMF exposure on heart rate (HR) and HR variability (HRV). The sample consisted of 34 healthy males aged 18-27 years. The participants were randomly assigned to the EMF (n = 17) or the Sham group (n = 17). We employed a double-blind repeated-measures design consisting of three 5 min experimental periods. The chest region of each individual in the EMF group was exposed to 50 Hz, 28 µT, linear polarized, continuous EMF during the EMF exposure period. HR and HRV data were recorded continuously by using a photoplethysmography sensor. Within-subject statistical analysis indicated a significant HR deceleration in both the EMF and Sham groups. However, the standard deviation of the NN intervals (SDNN), root mean square of successive differences (RMSSD), low-frequency (LF), and high-frequency (HF) powers increased only in the EMF group and remained stable in the Sham group. We also compared the same HRV indices measured during the EMF and Sham periods between the two experimental groups. The between-subject analysis results demonstrated significantly higher SDNN, RMSSD, LF, and HF values in the EMF group than in the Sham group. The LF/HF ratio did not change significantly within and between groups. On the basis of these results, we concluded that short-term exposure of the chest region to ELF-EMF could potentially enhance parasympathetic predominance during the resting condition. Bioelectromagnetics. 2021;42:60-75. © 2020 Bioelectromagnetics Society.

The Effects of Red Versus Blue Lights and Neuroticism on Voluntary Biceps Brachii Muscle Contraction.

This study investigated the effects of red and blue monochromatic lights and neuroticism on athletes' maximal isometric voluntary contraction (iMVC) level of the biceps brachii muscle. During elbow flexion, we measured iMVCs under a white light (control) condition and under red and blue light conditions. Under red light (vs. white and blue), participants demonstrated a greater iMVC level. Further, based on a median split of the athletes' scores on Tatar's Five Factor Personality Inventory, high and low neuroticism groups showed no red light differences, while, in the blue light condition, participants high in neuroticism increased the iMVC level by 4.04% and those low in neuroticism decreased iMVC level by 6.31%. Thus, the effect of colored light on athletes' motor output varied with individual personality differences in neuroticism.