Handling has an anxiolytic effect that is not affected by the inhibition of the protein kinase C pathway in adult prenatal undernourished male rat offspring

Increased Hippocampal Glucocorticoid Receptor Expression and Reduced Anxiety-Like Behavior Following Tuina in a Rat Model With Allergic Airway Inflammation

OBJECTIVE

This study aimed to explore the influence mechanism of Tuina on anxiety-like behavior in immature rats with allergic airway inflammation (AAI).

METHODS

A total of 27 Sprague-Dawley male rats (aged ∼5 weeks) were divided randomly into control, AAI, and AAI with Tuina groups (9 rats per group). The anxiety-like behavior was assessed by an open field test and elevated plus-maze test. Allergic airway inflammation was assessed based on the pathological score of the lung, plasma ovalbumin-specific immunoglobulin E, interleukin 4, interleukin 5, and tumor necrosis factor-alpha levels. Glucocorticoid receptor (GR) messenger RNA and protein expression in the hippocampus and lung were detected by polymerase chain reaction and immunohistochemistry, respectively. Meanwhile, corticotropin-releasing hormone (CRH) messenger RNA in the hypothalamus, the plasma levels of adrenocorticotropic hormone and corticosterone were also determined respectively by polymerase chain reaction and enzyme-linked immunosorbent assay for hypothalamic-pituitary-adrenal axis (HPA) function.

RESULTS

The AAI group had obvious anxiety-like behavior and hyperactive HPA axis, along with decreased GR expression in the hippocampus and lung. Following Tuina, AAI and the anxiety-like behavior were efficiently reduced, and the hyperactivity of HPA axis was efficiently inhibited, along with enhanced GR expression in the hippocampus and lung.

CONCLUSION

Glucocorticoid receptor expression in the hippocampus and lung was enhanced, and anxiety-like behavior was reduced following Tuina in rats with AAI.

Excessive folic acid intake combined with undernutrition during gestation alters offspring behavior and brain monoamine profiles

Dietary folic acid augmentation during gestation reduces neurodevelopmental disorder risk in offspring; however, it is still unclear if excessive maternal folic acid intake can impair brain function in offspring. We examined if excessive folic acid intake throughout gestation altered the behavior of male offspring under poor nutrition during early gestation (E5.5-E11.5). Dams were divided into four groups: control (CON, 2 mg folic acid/kg of food), excessive folic acid fortification (FF, 10 mg folic acid/kg of food), undernutrition (UN, 40% food reduction from E5.5-E11.5), and excessive folic acid fortification plus undernutrition (UN-FF). Excess maternal folic acid fortification induced hyperactivity in the open-field and lower anxiety-like behavior in the elevated plus maze at 9 weeks of age. These behavioral changes were accompanied by reduced dopamine in the prefrontal cortex (PFC), norepinephrine in the amygdala, and 5-hydroxytryptamine (5-HT) in the dorsal midbrain (DM), PFC, and amygdala where 5-HT neurons project from the DM. Furthermore, canonical discriminant analysis, including dopamine and DOPAC concentrations in the PFC, norepinephrine concentrations in the PFC, amygdala, and pons, and 5-HT and 5-HIAA concentrations in the amygdala and DM, correctly classified 73.5% of the offspring in CON, FF, UN, and UN-FF groups. The first discriminant function mainly classified groups based on nutritional status, whereas the second function mainly classified groups based on folic acid intake. Our study suggests that combined transformations of brain monoamine profiles by maternal undernutrition and excess folic acid intake is involved in the behavioral alteration of offsprings.

Postweaning Iron Deficiency in Male Rats Leads to Long-Term Hyperactivity and Decreased Reelin Gene Expression in the Nucleus Accumbens

BACKGROUND

Epidemiological research indicates that iron deficiency (ID) in infancy correlates with long-term cognitive impairment and behavioral disturbances, despite therapy. However, the mechanisms underlying these effects are unknown.

OBJECTIVE

We investigated how ID affected postweaning behavior and monoamine concentration in rat brains to determine whether ID during the juvenile period affected gene expression and synapse formation in the prefrontal cortex (PFC) and nucleus accumbens (NAcc).

METHODS

Fischer 344/Jcl postweaning male rats aged 21-39 d were fed low-iron diets (0.35 mg/kg iron; ID group) or standard AIN-93 G diets [3.5 mg/kg iron; control (CN) group]. After day 39, all rats were fed the iron-adequate diet. The locomotor activity was evaluated by the open field and elevated plus maze tests at 8 and 12 wk of age. Monoamine concentrations in the brain were analyzed using HPLC at 9 and 13 wk of age. Comprehensive gene expression analysis was performed in the PFC and NAcc at 13 wk of age. Finally, we investigated synaptic density in the PFC and NAcc by synaptophysin immunostaining.

RESULTS

Behavioral tests revealed a significant reduction of the age-related decline in the total distance traveled in ID rats compared with CN rats (P < 0.05), indicating that ID affected hyperactivity, which persisted into adulthood (13 wk of age). At this age, reelin (Reln) mRNA expression (adjusted P < 0.01) decreased and synaptic density (P < 0.01) increased in the NAcc in the ID group. Regarding the mesolimbic pathway, homovanillic acid concentration increased in the NAcc, whereas the dopamine concentration decreased in the ventral midbrain.

CONCLUSIONS

Our results suggest that ID during the postweaning period in male rats, despite complete iron repletion following ID, led to long-term hyperactivity via monoamine disturbance in the brain and an alteration in the synaptic plasticity accompanied by downregulation of Reln expression in the NAcc.

Change in Brain Plasmalogen Composition by Exposure to Prenatal Undernutrition Leads to Behavioral Impairment of Rats

Epidemiological studies suggest that poor nutrition during pregnancy influences offspring predisposition to experience developmental and psychiatric disorders. Animal studies have shown that maternal undernutrition leads to behavioral impairment, which is linked to alterations in monoaminergic systems and inflammation in the brain. In this study, we focused on the ethanolamine plasmalogen of the brain as a possible contributor to behavioral disturbances observed in offspring exposed to maternal undernutrition. Maternal food or protein restriction between gestational day (GD) 5.5 and GD 10.5 resulted in hyperactivity of rat male adult offspring. Genes related to the phospholipid biosynthesis were found to be activated in the PFC, but not in the NAcc or striatum, in the offspring exposed to prenatal undernutrition. Corresponding to these gene activations, increased ethanolamine plasmalogen (18:0p-22:6) was observed in the PFC using mass spectrometry imaging. A high number of crossings and the long time spent in the center area were observed in the offspring exposed to prenatal undernutrition and were mimicked in adult rats via the intravenous injection of ethanolamine plasmalogen (18:0p-22:6) incorporated into the liposome. Additionally, plasmalogen (18:0p-22:6) increased only in the PFC, and not in the NAcc or striatum. These results suggest that brain plasmalogen is one of the key molecules to control behavior, and its injection using liposome is a potential therapeutic approach for cognitive impairment.SIGNIFICANCE STATEMENT Maternal undernutrition correlates to developmental and psychiatric disorders. Here, we found that maternal undernutrition in early pregnancy led to hyperactivity in rat male offspring and induced gene activation of phospholipid-synthesizing enzyme and elevation of ethanolamine plasmalogen (18:0p-22:6) level in the PFC. Intravenous injection of ethanolamine plasmalogen (18:0p-22:6) incorporated into the liposome maintained crossing activity and the activity was circumscribed to the center area for a long time period, as in prenatally undernourished offspring with aberrant behavior. Furthermore, the amount of ethanolamine plasmalogen (18:0p-22:6) increased in the PFC of the rat after injection. Our result suggests that brain plasmalogen is one of the key molecules to control behavior and that its injection using liposome is a potential therapeutic approach for cognitive impairment.