Fluoxetine ameliorates adult hippocampal injury in rats after early maternal separation. A biochemical, histological and immunohistochemical study

Impact of polyphenols on stress and anxiety: a systematic review of molecular mechanisms and clinical evidence

Mental health is a global public concern that contributes raising disability and premature death. Anxiety undertakes around 3.6% of the global population, while psychological stress is a condition associated to anxiety with a prevalence of 36.5%. Treatment for both mental conditions consist mainly of psychological therapy and pharmacotherapy, but the long-term drugs use can trigger adverse effects. Growing evidence shows the effect of specific food compounds on stress and anxiety treatment. The aim of this systematic review is to describe the molecular mechanisms related to dietary polyphenols administration from food matrix (considering food, juices or herbal/food extracts) and their effects on stress and/or anxiety, as well as review the available clinical evidence. Search was based on PRISMA Guidelines using peer-reviewed journal articles sourced from PubMed and Web of Science. A total of 38 articles were considered as eligible. The major effects for anxiety management were: reduction of oxidative stress and inflammation; HPA axis modulation; and regulation of some serotonergic/adrenergic pathways. There is a very limited evidence to conclude about the real effect of dietary polyphenols on stress. Although pharmacological treatment for mood disorders is essential, alternative therapies are necessary using non-pharmacological compounds to improve the long-term treatment effectiveness.

Protective effects of Rosemary extract and/or Fluoxetine on Monosodium Glutamate-induced hippocampal neurotoxicity in rat

The use of Monosodium Glutamate (MSG) as a food flavor enhancer is increasing worldwide despite its neurotoxic effects. Fluoxetine (FLX) and Rosemary extract (RE) are known to have beneficial neuroprotective properties. Rats were divided into five groups: control group; MSG group, rats received 2 g/kg/day intraperitoneal (i.p.) injections of MSG for seven days; RE/MSG group, rats received 50 mg/kg/day of oral RE for 28 days starting prior to MSG; FLX/MSG group, rats received 10 mg/kg/day of oral FLX for 28 days beginning before MSG; and RE/FLX/MSG group, received combined treatments as mentioned above. Rats underwent the Barnes maze test, in addition to histopathological, immunohistochemical, morphometric and ultrastructural evaluations for their hippocampi. MSG increased the number of errors and escaped latency in the Barnes maze test that was significantly minimized in the three treatment groups. The MSG group exhibited pyramidal cell (PC) degeneration, shrunken glial cells and massive vascular dilatation that were improved with RE and/or FLX treatment. The number of glial fibrillary acidic protein (GFAP)-immunopositive cells were increased, and the number of PCs was decreased in the MSG group, while these values were significantly reversed with the three treatment groups with the most significant improvement at RE/FLX/MSG one. Ultrastructurally, PCs were shrunken with degenerated nuclei, dilated endoplasmic reticulum, swollen mitochondria, and vacuolations in the MSG group that were improved with RE and/or FLX. In conclusion, the combined RE and FLX treatment can ameliorate the toxic effect of MSG on rat hippocampus probably through its antioxidant and anti-inflammatory effects.

Maternal separation increases pain sensitivity by reducing the activity of serotonergic neurons in the dorsal raphe nucleus and noradrenergic neurons in locus coeruleus

Animals subjected to early life maternal separation exhibit increased sensitivity to chemical, thermal, and mechanical stimuli during adulthood. However, the mechanism by which maternal separation can alter pain sensitivity in adulthood has not yet been investigated. Thus, we aimed to evaluate the activity of serotonergic and noradrenergic neurons and the effect of serotonin (5-HT) and noradrenaline (NA) reuptake inhibitors in male and female Wistar rats subjected to maternal separation. This study consisted of two experiments: 1) to confirm whether maternal separation increased pain sensitivity (n = 8 per group) and to evaluate the activity of serotonergic neurons in the dorsal raphe nucleus and noradrenergic neurons in locus coeruleus in animals subjected to maternal separation in comparison to controls (n = 6 per group); and 2) to evaluate the effect of fluoxetine (a selective 5-HT reuptake inhibitor) and desipramine (a NA reuptake inhibitor) on sensitivity to chemical stimulation using formalin in animals subjected to maternal separation (n = 8 per group). Our findings indicated that maternal separation increases an animal's sensitivity to painful chemical stimulation and reduces the activity of 5-HT and NA neurons. In addition, acute pretreatment with a 5-HT or NA reuptake inhibitor prevented the increased response to painful stimulation induced by maternal separation. In conclusion, maternal separation increases pain sensitivity by reducing the activity of serotonergic neurons in the dorsal raphe nucleus and noradrenergic neurons in locus coeruleus. This study contributes to possible treatments for pain in individuals exposed to early life stress.

Anxiolytic and antioxidant effects of Euterpe oleracea Mart. (açaí) seed extract in adult rat offspring submitted to periodic maternal separation

Many studies suggest a protective role of phenolic compounds in mood disorders. We aimed to assess the effect of Euterpe oleracea (açaí) seed extract (ASE) on anxiety induced by periodic maternal separation (PMS) in adult male rats. Animals were divided into 6 groups: control, ASE, fluoxetine (FLU), PMS, PMS+ASE, and PMS+FLU. For PMS, pups were separated daily from the dam for 3 h between postnatal day (PN) 2 and PN21. ASE (200 mg·kg^-1·day^-1) and FLU (10 mg·kg^-1·day^-1) were administered by gavage for 34 days after stress induction, starting at PN76. At PN106 and PN108, the rats were submitted to open field (OF) and forced swim tests, respectively. At PN110, the rats were sacrificed by decapitation. ASE increased time spent in the center area in the OF test, glucocorticoid receptors in the hypothalamus, tropomyosin receptor kinase B (TRKB) levels in the hippocampus, and nitrite levels and antioxidant activity in the brain stem (PMS+ASE group compared with PMS group). ASE also reduced plasma corticotropin-releasing hormone levels, adrenal norepinephrine levels, and oxidative damage in the brain stem in adult male offspring submitted to PMS. In conclusion, ASE treatment has an anti-anxiety effect in rats submitted to PMS by reducing hypothalamic-pituitary-adrenal axis reactivity and increasing the nitric oxide (NO)-brain-derived neurotrophic factor (BDNF)-TRKB pathway and antioxidant defense in the central nervous system. Novelty ASE has anti-anxiety and antioxidant effects in early-life stress. ASE reduces hypothalamic-pituitary-adrenal axis reactivity. The anxiolytic effect of ASE may involve activation of the NO-BDNF-TRKB pathway in the central nervous system.