Effects of Ocimum basilicum L. Extract on Hippocampal Oxidative Stress, Inflammation, and BDNF Expression in Amnesic Aged Rats

The present study was conducted to investigate the effects of Ocimum basilicum L. (OB) extract on learning and memory impairment in aged rats. Male rats were divided into the following experimental groups: Group 1 (control): including 2 months old rats, Group 2 (aged) including 2 years old rats, Groups 3-5 (aged-OB): including 2 years old rats received 50, 100, and 150 mg/kg OB for 8 weeks by oral gavage. Aging increased the delay to find the platform but, however, decreased the time spent in the target quadrant when tested by Morris water maze (MWM). Aging also reduced the latency to enter the dark chamber in the passive avoidance (PA) test compared to the control group. Moreover, interleukin-6 (IL-6) and malondialdehyde (MDA) levels were raised in the hippocampus and cortex of aged rats. In contrast, thiol levels and enzymatic activity of superoxide dismutase (SOD) and catalase (CAT) significantly reduced. In addition, aging significantly reduced BDNF expression. Finally, OB administration reversed the mentioned effects. The current research showed that OB administration improves learning/memory impairment induced by aging. It also found that this plant extract protects the brain tissues from oxidative damage and neuroinflammation.

Metabolomics-Based Effects of a Natural Product on Remyelination After Cerebral Ischemia Injury Via GABABR-pCREB-BDNF Pathway

BACKGROUND

Yi-Qi-Tong-Luo Granules (YQTLs) is a natural compound of Traditional Chinese Medicine authorized by China Food and Drug Administration (CFDA). These granules are employed in the convalescent stage of cerebral infarction and render notable clinical efficacy. This study aims to uncover the underlying mechanisms of YQTLs on remyelination after cerebral ischemia injury.

MATERIALS AND METHODS

We established cerebral ischemia model in rats using microsphere-induced multiple cerebral infarction (MCI). We evaluated the pharmacological effects of YQTLs on MCI rats, through Morri's water maze test, open field test, hematoxylin and eosin staining, and glycine silver immersion. We employed liquid chromatography mass spectrometry metabolomics to identify differential metabolites. Enzyme-linked immunosorbent assay was utilized to measure the release of neurotrophins, while immunofluorescence staining was used to assess oligodendrocyte precursor cells differences and myelin regeneration. We used Western blotting to validate the protein expression of remyelination-associated signaling pathways.

RESULTS

YQTLs significantly improves cognitive function following cerebral ischemia injury. Pathological tissue staining revealed that YQTLs administration inhibits neuronal denaturation and neurofibrillary tangles. We identified 141 differential metabolites among the sham, MCI, and YQTLs-treated MCI groups. Among these metabolites, neurotransmitters were identified, and notably, gamma-aminobutyric acid (GABA) showed marked improvement in the YQTLs group. The induction of neurotrophins, such as brain-derived neurotrophic factor (BDNF) and PDGFAA, upregulation of olig2 and MBP expression, and promotion of remyelination were evident in YQTLs-treated MCI groups. Gamma-aminobutyric acid B receptors (GABABR), pERK/extracellular regulated MAP kinase, pAKT/protein kinase B, and pCREB/cAMP response element-binding were upregulated following YQTLs treatment.

CONCLUSION

YQTLs enhance the binding of GABA to GABABR, thereby activating the pCREB/BDNF signaling pathway, which in turn increases the expression of downstream myelin-associated proteins and promotes remyelination and cognitive function.

Effects of carbamazepine on BDNF expression in trigeminal ganglia and serum in rats with trigeminal neuralgia

OBJECTIVES

Trigeminal neuralgia (TN) is a severe chronic neuropathic pain that mainly affects the distribution area of the trigeminal nerve with limited treating efficacy. There are numerous treatments for TN, but currently the main clinical approach is to suppress pain by carbamazepine (CBZ). Brain-derived neurotrophic factor (BDNF) is closely related to chronic pain. This study aims to determine the effects of CBZ treatment on BDNF expression in both the trigeminal ganglion (TG) and serum of TN via a chronic constriction injury of the infraorbital nerve (ION-CCI) rat model.

METHODS

The ION-CCI models were established in male Sprague-Dawley rats and were randomly divided into a sham group, a TN group, a TN+low-dose CBZ treatment group (TN+20 mg/kg CBZ group), a TN+medium-dose CBZ treatment group (TN+40 mg/kg CBZ group), and a TN+high-dose CBZ treatment group (TN+80 mg/kg CBZ group). The mechanical pain threshold in each group of rats was measured regularly before and after surgery. The expressions of BDNF and tyrosine kinase receptor B (TrkB) mRNA in TGs of rats in different groups were determined by real-time PCR, and the expression of BDNF protein on neurons in TGs was observed by immunofluorescence. Western Blotting was used to detect the protein expression of BDNF, TrkB, extracellular regulated protein kinases (ERK), and phospho-extracellular regulated protein kinases (p-ERK) in TGs of rats in different groups. The expression of BDNF in the serum of rats in different groups was detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The results of mechanical pain sensitivity showed that there was no significant difference in the mechanical pain threshold in the right facial sensory area of the experimental rats in each group before surgery (all P>0.05). From the 3rd day after operation, the mechanical pain threshold of rats in the TN group was significantly lower than that in the sham group (all P<0.01), and the mechanical pain threshold of rats in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 CBZ mg/kg group was higher than that in the TN group (all P<0.05). The BDNF and TrkB mRNA and protein expressions in TGs of rats in the TN group were higher than those in the sham group (all P<0.05), and those in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than the TN group (all P<0.05). The p-ERK levels in TG of rats in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were significantly decreased compared with the TN group (all P<0.05). The BDNF and neuron-specific nuclear protein (NeuN) were mainly co-expressed in neuron of TGs in the TN group and they were significantly higher than those in the sham group (all P<0.05). The co-labeled expressions of BDNF and NeuN in TGs of the TN+ 80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than those in the TN group (all P<0.05). The results of ELISA showed that the level of BDNF in the serum of the TN group was significantly higher than that in the sham group (P<0.05). The levels of BDNF in the TN+80 mg/kg CBZ group, the TN+40 mg/kg CBZ group, and the TN+20 mg/kg CBZ group were lower than those in the TN group (all P<0.05). Spearman correlation analysis showed that the BDNF level in serum was negatively correlated with mechanical pain threshold (r=-0.650, P<0.01).

CONCLUSIONS

CBZ treatment can inhibit the expression of BDNF and TrkB in the TGs of TN rats, reduce the level of BDNF in serum of TN rats and the phosphorylation of ERK signaling pathway, so as to inhibit TN. The serum level of BDNF can be considered as an indicator for the diagnosis and prognosis of TN.

Engeletin alleviates depression-like phenotype by increasing synaptic plasticity via the BDNF-TrkB-mTORC1 signalling pathway

Major depressive disorder (MDD) is a severe mental disorder associated with high rates of morbidity and mortality. Current first-line pharmacotherapies for MDD are based on enhancement of monoaminergic neurotransmission, but these antidepressants are still insufficient and produce significant side-effects. Consequently, the development of novel antidepressants and therapeutic targets is desired. Engeletin, a natural Smilax glabra rhizomilax derivative, is a compound with proven efficacy in treating ischemic stroke, yet its therapeutic effects and mechanisms for depression remain unexplored. The effects of engeletin were assessed in the forced swimming test (FST) and tail suspension test (TST) in mice. Engeletin was also investigated in the chronic restraint stress (CRS) mouse model of depression with fluoxetine (FLX) as the positive control. Changes in prefrontal cortex (PFC) spine density, synaptic plasticity-linked protein expressions and the brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB)- mammalian target of rapamycin complex 1 (mTORC1) signalling pathway after chronic stress and engeletin treatment were then investigated. The TrkB and mTORC1 selective inhibitors, ANA-12 and rapamycin, respectively, were utilized to assess the engeletin's antidepressive mechanisms. Our data shows that engeletin exhibited antidepressant-like activity in the FST and TST in mice without affecting locomotor activity. Furthermore, it exhibited efficiency against the depression of CRS model. Moreover, it enhanced the BDNF-TrkB-mTORC1 pathway in the PFC during CRS and altered the reduction in dendritic spine density and levels of synaptic plasticity-linked protein induced by CRS. In conclusion, engeletin has antidepressant activity via activation of the BDNF-TrkB-mTORC1 signalling pathway and upregulation of PFC synaptic plasticity.

Acetoacetate Improves Memory in Alzheimer's Mice via Promoting Brain-Derived Neurotrophic Factor and Inhibiting Inflammation

The ketone bodies, especially the β-hydroxybutyrate, had been shown to modulate the function of the central nervous system and prevent the pathological progression of Alzheimer's disease (AD). However, little is known about the role of acetoacetate in the AD brain. Thus, we intraventricularly injected acetoacetate into familial AD mice (APPSWE) for 14 days and monitored their memory and biochemical changes. During the behavior test, acetoacetate at 100 mg/kg led to significant improvement in both Y-maze and novel object recognition tests (NORTs) (both P < .05), indicating ameliorating spatial and recognition memory, respectively. Biomedical tests revealed two mechanisms were involved. Firstly, acetoacetate inhibited the GPR43-pERK pathway, which led to apparent inhibition in tumor necrosis factor-α and Interleukin-6 expression in the hippocampus in a concentration-dependent manner. Secondarily, acetoacetate stimulated the expression of hippocampal brain-derived neurotrophic factor (BDNF). We concluded that acetoacetate could ameliorate AD symptoms and exhibited promising features as a therapeutic for AD.

Possible therapeutic effect of royal jelly on endometriotic lesion size, pain sensitivity, and neurotrophic factors in a rat model of endometriosis

Endometriosis is the abnormal growth of endometrial tissue. The goals of the study are: (1) Is any correlation between endometriosis pain and neurotrophins in the serum, dorsal root ganglion (DRG), and peritoneal fluid (PF) in rat models of experimental endometriosis?, (2) Possible therapeutic effects of royal jelly (RJ) on pain scores, size of endometriotic lesion, and neurotrophic factors. Forty-eight Sprague Dawley female rats weighing 205.023 ± 21.54 g were maintained in a standard condition. The rats were randomly divided into one of the six groups: Control (no intervention), Sham-1 (remove of uterine horn), RJ (administration of 200 mg/kg/day RJ for 21 days), Endometriosis (induction of endometriosis), Treatment (induction of endometriosis+administration of 200 mg/kg/day RJ for 21 days), and Sham-2 (induction of endometriosis+administration of water). Formalin test performed for pain evaluation. The levels of Brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), substance P, and calcitonin gene-related peptide (CGRP) were measured by enzyme-linked immunosorbent assay. The mean pain scores in all three phases of the formalin test were significantly increased by endometriosis induction (p < 0.05). The concentrations of BDNF, NGF, and CGRP in DRG of the endometriosis group were significantly higher than these factors in the Control, Sham-1, and RJ groups (p < 0.05). RJ could significantly (p < 0.001) decrease the mean lesion size and the mean pain score in the late phase (p < 0.05). The present results determine that endometriosis pain may be related to nervous system neurotrophic factors. Treatment with RJ could decrease the size of endometriosis lesions as well as pain scores. The findings may shed light on other complementary and alternative remedies for endometriosis.

Decreased spasticity of Baishaoluoshi Decoction through the BDNF/TrKB-KCC2 pathway on poststroke spasticity rats

OBJECTIVE

K+-Cl- cotransporter-2 (KCC2), which primarily extrudes chloride in mature neurons, triggers hemiplegia limb spasticity after ischemic stroke by affecting neuronal excitability. Our previous study revealed that the Chinese herb Baishaoluoshi Decoction decreases hemiplegia limb spasticity in poststroke spasticity (PSS) patients. This study aimed at elucidating on the effects of Baishaoluoshi Decoction on the BDNF/TrKB-KCC2 pathway in PSS rat models.

METHODS

Middle cerebral artery occlusion (MCAO) was adopted for the establishment of PSS rat models. Muscle tension was evaluated by Modified Ashworth Scale. Nissl staining and transmission electron microscopy were used to measure the protective effects of Baishaoluoshi Decoction on ischemic injury-induced neuronal damage due to MCAO. Expression levels of BDNF, TrKB, and KCC2 in brain tissues around the infarct and brainstem were detected by immunohistochemical staining.

RESULTS

It was found that Baishaoluoshi Decoction suppressed hemiplegia limb spasticity and alleviated the damage in neurons and synapses in PSS rat models. Importantly, the expression of BDNF, TrKB, and KCC2 in brain tissues around the infarct and brainstem were significantly upregulated after treatment with low-dose and high-dose Baishaoluoshi Decoction.

CONCLUSION

Suppression of spasticity by Baishaoluoshi Decoction in PSS rat models may be correlated with upregulated BDNF/TrKB-KCC2 pathway, which may be a complementary therapeutic strategy for PSS.

Sigma 1 receptor agonist cutamesine promotes plasticity of serotonergic boutons in lumbar enlargement in spinal cord injured rats

Cutamesine, a sigma-1 receptor agonist, functions in both neuroprotection and neurite outgrowth. We assessed the therapeutic effects of cutamesine in a rodent spinal cord injury (SCI) model to demonstrate pre-clinical proof-of-concept. First of all, in order to determine optimal cutamesine dose, cutamesine was administered to normal rats and BDNF protein levels in the lumbar spinal cord were assessed by Western blot. Next, for the SCI model, spinal cords of adult female Sprague-Dawley rats were contused using an Infinite Horizon Impactor. Two weeks post-injury, rats were randomly assigned to receive daily subcutaneous injections of either cutamesine (3.0 mg/kg/day) or saline (as a control) for another two weeks. Immunohistochemistry for BDNF and 5-HT was assessed at four and twelve weeks post-injury in the lumbar spinal cord. Locomotor function was assessed weekly using the BBB locomotor scale until twelve weeks after SCI and CatWalk XT 10.5 gait analysis was conducted at twelve weeks after SCI. In normal rats, cutamesine treatment (3.0 mg/kg/day) significantly up-regulated BDNF expression in the lumbar spinal cord. In SCI rats, cutamesine treatment (3.0 mg/kg/day) significantly increased the fluorescence intensity of neuronal BDNF and serotonin boutons in the injured spinal cord compared to saline. However, cutamesine treatment did not promote significant locomotor recovery. Recent work indicates that cutamesine treatment alone did not promote locomotor recovery in spite of immunohistological changes. Future work will explore the influence of combining cutamesine with other treatment promoting plasticity (e.g. rehabilitative training) in SCI rats.

Prophylactic effects of sporoderm-removed Ganoderma lucidum spores in a rat model of streptozotocin-induced sporadic Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Ganoderma lucidum (G. lucidum, Lingzhi), also known as "immortality mushroom" has been broadly used to improve health and longevity for thousands of years in Asia. G. lucidum and its spores have been used to promote health, based on its broad pharmacological and therapeutic activity. This species is recorded in Chinese traditional formula as a nootropic and has been suggested to improve cognitive dysfunction in Alzheimer's disease. However, little is known about the nootropic effects and molecular mechanism of action of G. lucidum spores.

AIM OF THE STUDY

The present study investigated the protective effects of sporoderm-deficient Ganoderma lucidum spores (RGLS) against learning and memory impairments and its mechanism of action.

MATERIALS AND METHODS

In the Morris water maze, the effects of RGLS on learning and memory impairments were evaluated in a rat model of sporadic Alzheimer's disease that was induced by an intracerebroventricular injection of streptozotocin (STZ). Changes in amyloid β (Aβ) expression, Tau expression and phosphorylation, brain-derived neurotrophic factor (BDNF), and the BDNF receptor tropomyosin-related kinase B (TrkB) in the hippocampus were evaluated by Western blot.

RESULTS

Treatment with RGLS (360 and 720 mg/kg) significantly enhanced memory in the rat model of STZ-induced sporadic Alzheimer's disease and reversed the STZ-induced increases in Aβ expression and Tau protein expression and phosphorylation at Ser199, Ser202, and Ser396. The STZ-induced decreases in neurotrophic factors, including BDNF, TrkB and TrkB phosphorylation at Tyr816, were reversed by treatment with RGLS.

CONCLUSION

These findings indicate that RGLS prevented learning and memory impairments in the present rat model of STZ-induced sporadic Alzheimer's disease, and these effects depended on a decrease in Aβ expression and Tau hyperphosphorylation and the modulation of BDNF-TrkB signaling in the hippocampus.

Ghrelin treatment leads to dendritic spine remodeling in hippocampal neurons and increases the expression of specific BDNF-mRNA species

Ghrelin (Gr) is an orexigenic peptide that acts via its specific receptor, GHSR-1a distributed throughout the brain, being mainly enriched in pituitary, cortex and hippocampus (Hp) modulating a variety of brain functions. Behavioral, electrophysiological and biochemical evidence indicated that Gr modulates the excitability and the synaptic plasticity in Hp. The present experiments were designed in order to extend the knowledge about the Gr effect upon structural synaptic plasticity since morphological and quantitative changes in spine density after Gr administration were analyzed "in vitro" and "in vivo". The results show that Gr administered to hippocampal cultures or stereotactically injected in vivo to Thy-1 mice increases the density of dendritic spines (DS) being the mushroom type highly increased in secondary and tertiary extensions. Spines classified as thin type were increased particularly in primary extensions. Furthermore, we show that Gr enhances selectively the expression of BDNF-mRNA species.

Norepinephrine in the dentate gyrus is involved in spatial learning and memory alteration induced by chronic restraint stress in aged rats

The role of norepinephrine of the hippocampal dentate gyrus in spatial learning and memory alteration induced by chronic restraint stress (CRS, 3 h/day, 6 weeks) was investigated in aged rats. Spatial learning and memory were assessed by the Morris water maze (MWM), and the extracellular concentration of norepinephrine and amplitude of field excitatory postsynaptic potential (fEPSP) were measured in the dentate gyrus during MWM test in freely-moving rats. Next, the involvement of β-adrenoceptors in spatial learning and memory of CRS rats was examined by microinjection of its antagonist (propranolol) into the dentate gyrus. In addition, we observed the expression of brain-derived neurotrophic factor (BDNF) protein and activation of cAMP-response element binding protein (CREB) in the dentate gyrus. Compared with the control group, the basal level of norepinephrine, BDNF expression and CREB activation in the dentate gyrus were increased, and the spatial learning and memory abilities were enhanced in CRS rats. In the control group, the norepinephrine concentration and fEPSP amplitude in the dentate gyrus were increased on the second to fourth days of MWM test, and these responses were significantly enhanced in CRS rats. Furthermore, in CRS rats, propranolol significantly decreased the spatial learning and memory abilities, and attenuated the fEPSP response during MWM test, and the BDNF expression and CREB activation in the dentate gyrus. Our results suggest that norepinephrine activation of β-adrenoceptors in the hippocampal dentate gyrus is involved in spatial learning and memory enhancement induced by CRS in aged rats, in part via modulations of synaptic efficiency and CREB-BDNF signaling pathway.

Antidepressant-like activity of L-701324 in mice: A behavioral and neurobiological characterization

Antidepressants currently used in clinical practice have limitations such as low efficacy, slow onset and various adverse reactions. It has become necessary to develop novel antidepressants beyond monoaminergic drugs. L-701,324 is a potent NMDA receptor antagonist, and the purpose of this study was to investigate the possible antidepressant effects of L-701,324 in mice. Here, various methods including the forced swim test (FST), tail suspension test (TST), chronic unpredictable mild stress (CUMS) model of depression, western blotting and immunofluorescence, were used together. A single injection of L-701,324 exhibited antidepressant-like potential in the FST and TST without affecting the locomotor activity of mice. Repeated injection of L-701,324 not only prevented CUMS-induced depressive-like behaviors in mice, but also ameliorated the downregulating effects of CUMS on the hippocampal BDNF signaling cascade and neurogenesis. Furthermore, K252a, a potent inhibitor of the BDNF system, fully blocked the antidepressant-like activity of L-701,324 in mice. K252a administration also abolished the activating actions of L-701,324 on the hippocampal BDNF signaling cascade and neurogenesis in CUMS-treated mice. Collectively, these data indicated that L-701,324 possesses antidepressant-like activity in mice, which was mediated, at least in part, by promoting the hippocampal BDNF system.

Dammarane sapogenins attenuates stress-induced anxiety-like behaviors by upregulating ERK/CREB/BDNF pathways

Dammarane sapogenins (DS), an extract derived from ginseng by alkaline hydrolysis of total ginsenosides, possesses high pharmacological activity and higher bioavailability than ginsenosides. The present study was designed to investigate the anxiolytic-like effects of DS in a mouse model of chronic social defeat stress (CSDS). DS (40 and 80 mg/kg) significantly ameliorated social avoidance and anxiety-like behavior in four test models of CSDS, showing increased time in the interaction zone in the social interaction test and in the center of the field in the open field test, an increased percentage of entries and open arm time in the elevated plus maze, and reduced latency to eat in the novelty-suppressed feeding test. Biochemical analyses showed that DS significantly reduced serum corticosterone levels and increased brain concentration of neurotransmitter 5-HT and noradrenaline in CSDS mice. Treatment with DS significantly upregulated BDNF (brain-derived neurotrophic factor), p-CREB/CREB and p-ERK1/2/ERK1/2 protein expression in the hippocampus and prefrontal cortex of CSDS mice. Collectively, these results suggest that DS exerts anxiolytic-like effects in CSDS model mice and the action is mediated, at least in part, by modulating the HPA (hypothalamic-pituitary-adrenal) axis and monoamine neurotransmitter levels, and via ERK/CREB/BDNF signaling pathway.

Polyphenols selectively reverse early-life stress-induced behavioural, neurochemical and microbiota changes in the rat

There is a growing emphasis on the role of the microbiota-gut-brain axis as modulator of host behaviour and as therapeutic target for neuropsychiatric disorders. In addition, accumulating evidence suggests that early-life stress can exert long-lasting changes on the brain and microbiota, and this early adversity is associated with increased risk for developing depression in later life. The maternal separation (MS) model in rats is a robust paradigm to study the effects of early-life stress on the microbiota-gut-brain axis. Recently, we have shown that polyphenols, naturally occurring compounds associated with several health benefits, have anti-stress effects in in vitro models. In this study, we assess the therapeutic potential of a variety of both flavonoid and non-flavonoid polyphenols in reversing the impact of MS on behaviour and the microbiota-gut-brain axis. Rats underwent a dietary intervention with the naturally-derived polyphenols xanthohumol and quercetin, as well as with a phlorotannin extract for 8 weeks. Treatment with polyphenols prevented the depressive- and anxiety-like behaviours induced by MS, where xanthohumol effects were correlated with rescue of BDNF plasma levels. In addition, MS resulted in altered brain levels of 5-hydroxyindoleacetic acid (5-HIAA) and dopamine, accompanied by abnormal elevation of plasma corticosterone. Although polyphenols did not reverse neurotransmitter imbalance, xanthohumol normalised corticosterone levels in MS rats. Finally, we explored the impact of MS and polyphenolic diets on the gut microbiota. We observed profound changes in microbial composition and diversity produced by MS condition and by xanthohumol treatment. Moreover, functional prediction analysis revealed that MS results in altered enrichment of pathways associated with microbiota-brain interactions that are significantly reversed by xanthohumol treatment. These results suggest that naturally-derived polyphenols exert antidepressant-like effects in MS rats, which mechanisms could be potentially mediated by HPA regulation, BDNF levels rescue and modulation of the microbiota-gut-brain axis.

Beyond the monoamine hypothesis: mechanisms, molecules and methods

The first effective antidepressants (monoamine oxidase inhibitors and tricyclic antidepressants) relied on their ability to augment serotonin and noradrenaline levels at the synapse. Forty years later, the same biological model led to the supremacy of the serotonergic hypothesis to explain not only the pathophysiology of depressive illness, but also the neuropharmacological basis for obsessive compulsive disorder, phobias, posttraumatic stress disorder, and even generalized anxiety disorder. It could be argued that the blinkered view of depression as a solely serotonergic phenomenon has not only restrained and limited research into other potential systems, but has also slowed down the discovery of putative antidepressant drugs. While some might argue that the hypothalamic-pituitary-adrenal (HPA) axis explains an individual’s sensitivity to depression, there are others who equally claim that the most likely explanations are to be found in the neuropsychopharmacology of the immune system or even through reductions in hippocampal volume. There is a richness of possibilities regarding the mechanisms for antidepressant activity embracing theoretical, pharmacological and clinical data. However, the methods by which putative antidepressants are assessed and their clinical efficacy demonstrated are not always robust. That current clinical comparisons of antidepressants rarely show major differences in efficacy between existing molecules could be taken as an indication that “all drugs are the same” or perhaps, more insightfully, as an indication that the ubiquitous Hamilton depression (HAM-D) rating scales are not sensitive to inter-drug differences, even though pronounced pharmacodynamic differences between molecules are easily demonstrated. Any advances in the development of new antidepressants will have to find not only original compounds but also unique psychometric tests by which the drugs can be assessed in a sensitive, reliable, and valid manner.

Effect of Zinc Supplementation on Physical and Psychological Symptoms, Biomarkers of Inflammation, Oxidative Stress, and Brain-Derived Neurotrophic Factor in Young Women with Premenstrual Syndrome: a Randomized, Double-Blind, Placebo-Controlled Trial

Zinc is known to have multiple beneficial effects including anti-inflammatory and antioxidant and anti-depressant actions. Data on the effects of zinc supplementation on biomarkers of inflammation, oxidative stress, and antidepressant-like effect among young women with premenstrual syndrome (PMS) are scarce. This study was a randomized, double-blind, placebo-controlled trial. Sixty women (18-30 years) with premenstrual syndrome diagnosed according to 30-item questionnaire were randomly assigned to receive either 30-mg zinc gluconate (group 1; n = 30) and/or placebo (group 2; n = 30) for 12 weeks. Premenstrual syndrome symptoms, total antioxidant capacity, high sensitivity reactive protein, and brain-derived neurotrophic factor were measured at study baseline and after 12-week intervention. After 12 weeks of intervention, PMS physical symptoms (P = 0.03) and psychological symptoms (P = 0.006) significantly decreased in zinc group compared to placebo group. We observed a significant increase in brain-derived neurotrophic factor (P = 0.01) and total antioxidant capacity (P ˂ 0.001) after 12 weeks of intervention with zinc compared to placebo. We failed to find any significant effect of zinc supplementation on high sensitivity reactive protein. Overall, zinc supplementation for 12 weeks among women with premenstrual syndrome had beneficial effects on physical and psychological symptoms of premenstrual syndrome, total antioxidant capacity, and brain-derived neurotrophic factor.

CSF1R inhibitor PLX5622 and environmental enrichment additively improve metabolic outcomes in middle-aged female mice

As the elderly population grows, chronic metabolic dysfunction including obesity and diabetes are becoming increasingly common comorbidities. Hypothalamic inflammation through CNS resident microglia serves as a common pathway between developing obesity and developing systemic aging pathologies. Despite understanding aging as a life-long process involving interactions between individuals and their environment, limited studies address the dynamics of environment interactions with aging or aging therapeutics. We previously demonstrated environmental enrichment (EE) is an effective model for studying improved metabolic health and overall healthspan in mice, which acts through a brain-fat axis. Here we investigated the CSF1R inhibitor PLX5622 (PLX), which depletes microglia, and its effects on metabolic decline in aging in interaction with EE. PLX in combination with EE substantially improved metabolic outcomes in middle-aged female mice over PLX or EE alone. Chronic PLX treatment depleted 75% of microglia from the hypothalamus and reduced markers of inflammation without affecting brain-derived neurotrophic factor levels induced by EE. Adipose tissue remodeling and adipose tissue macrophage modulation were observed in response to CSF1R inhibition, which may contribute to the combined benefits seen in EE with PLX. Our study suggests benefits exist from combined drug and lifestyle interventions in aged animals.

Paternal morphine exposure induces bidirectional effects on cocaine versus opioid self-administration

The United States is in the midst of an opioid epidemic and is thus experiencing unprecedented levels of opioid exposure. A growing body of evidence has demonstrated that this may have consequences on multiple generations. The current set of experiments examined the effect of male adolescent opioid exposure on cocaine and opioid self-administration in the F1 generation. Male Sprague Dawley rats were administered increasing doses of morphine (5-25 mg/kg, s.c.) for 10 days during adolescence (P30-39). Rats were then maintained drug free until adulthood (P70-80) at which point they were mated with drug-naïve females. Male and female F1 offspring were first examined for cocaine self-administration during adulthood. Naïve littermates were tested for morphine self-administration acquisition followed by a within subjects design progressive ratio test for morphine, oxycodone, and cocaine. Results show that male and female F1 rats have delayed acquisition and decreased intake of cocaine. In addition, they have blunted PR levels compared to Sal-F1 control rats. Female Mor-F1 rats also demonstrate increased levels of morphine intake during acquisition and increased PR responding for oxycodone. Surprisingly, even following acquisition of morphine self-administration, Mor-F1 males and females still demonstrate blunted effort for cocaine. There were no differences in sucrose self-administration in naïve littermates. MorF0 seminiferous tubules demonstrated increased levels of acetylated histone H3 and there were increased levels of BDNF mRNA in the mPFC in male and female F1 offspring. Together, these data identify systems that are vulnerable to the impact of opioids in the F0 generation.

Grape-derived polyphenols produce antidepressant effects via VGF- and BDNF-dependent mechanisms

Recent studies suggest that bioactive dietary polyphenol preparation (BDPP) and individual polyphenolic compounds ameliorate stress-induced depression-like behaviors, but the underlying molecular mechanisms are incompletely understood. VGF (non-acronymic) in the dorsal hippocampus (dHc) has been shown to play a role in depression-like behaviors and antidepressant efficacy, and the VGF-derived peptide TLQP-62 (named by the N-terminal 4 amino acids and length) infused into dHc has been shown to have antidepressant efficacy that is BDNF-TrkB dependent. Here, we investigated whether BDPP influences VGF expression in the dHc, and whether dHc VGF is required for BDPP antidepressant efficacy. We found that BDPP produced antidepressant-like effects in naive mice and reversed the depression-like behaviors induced by chronic variable stress. In addition, we found that BDPP had no detectable antidepressant efficacy in floxed mice with prior knockdown in the dHc of either VGF or BDNF, achieved by adeno-associated virus-Cre infusion. Our data indicate that dHc VGF and BDNF expression are required for the antidepressant actions of BDPP, and therefore suggest that a VGF(TLQP-62)-BDNF-TrkB autoregulatory feedback loop could play a role in the regulation of BDPP antidepressant efficacy, much as it has been suggested to function in the antidepressant efficacies of ketamine and TLQP-62.

Endoplasmic reticulum stress in the livers of BDNF heterozygous knockout mice

Context: Involvement of endoplasmic reticulum (ER) stress and brain-derived neurotrophic factor (BDNF) in hepatic lipid metabolism has been reported previously. Objective: The effects of chronic BDNF deficiency on ER stress response in the livers were examined in this study. Methods: BDNF^(+/-) mice, characterised by BDNF deficiency, and their wild-type (WT) littermates were used. The ER stress was induced by tunicamycin (Tm) (0.5 mg/kg, intraperitoneal). Animals were divided into four groups; WT, WT + Tm, BDNF^(+/-), and BDNF^(+/-)+Tm. Results: At the basal conditions, BDNF deficiency did not affect hepatic cell death or lipid accumulation. However, during ER stress, BDNF^(+/-)+Tm group showed increased apoptosis, GADD153 immunostaining, sterol regulatory element-binding protein-1c (SREBP-1c) level, and steatosis compared to the WT + Tm group. Conclusion: Endogenous BDNF might be protective against apoptosis through GADD153 suppression and steatosis via SREBP-1c suppression during ER stress. This effect of BDNF might be clinically important for type 2 diabetes and obesity, which are related with both ER stress and BDNF deficiency.

Renal response to tunicamycin-induced endoplasmic reticulum stress in BDNF heterozygous mice

BACKGROUND

The protective effects of brain-derived neurotrophic factor (BDNF) against endoplasmic reticulum (ER) stress in neuronal tissue and endometrial cells have been reported.

OBJECTIVES

The aim of this study was to determine whether endogenously produced BDNF protects the kidneys against tunicamycin-induced (Tm) ER stress.

MATERIAL AND METHODS

Brain-derived neurotrophic factor heterozygous knockout mice (BDNF(+/-)) and their wild-type (WT) littermates were used. The animals were divided into 4 groups: WT, BDNF(+/-), WT+Tm, and BDNF(+/-)+Tm (n = 7 in each group). After 3 days of saline or Tm injection (0.5 mg/kg; intraperitoneally (i.p.)), renal BDNF, glucose-regulated protein 78 (GRP78), and caspase-12 levels as well as serum BDNF concentration were measured with enzyme-linked immunosorbent assay (ELISA). In the kidney sections, hematoxylin & eosin (H&E) staining, GADD153 immunostaining and TUNEL staining were performed. Serum creatinine levels were measured as an indicator of renal function.

RESULTS

Circulating and tissue BDNF levels were significantly lower in the BDNF(+/-) and BDNF(+/-)+Tm groups. Renal levels of GRP78 and caspase-12, apoptotic index, and GADD153 staining were significantly higher in the WT+Tm and BDNF(+/-)+Tm groups. However, apoptosis was more pronounced in the BDNF(+/-)+Tm group than in the WT+Tm group (p < 0.01). Similarly, GADD153 staining was more pronounced in the BDNF(+/-)+Tm group than in the WT+Tm group (p < 0.05). Tm caused a mild deterioration in the kidney tissue of the WT+Tm group, while general deterioration, pyknotic nuclei and swollen cells were observed in the BDNF(+/-)+Tm group. Serum creatinine concentrations were significantly higher in the WT+Tm (p < 0.05) and BDNF(+/-)+Tm (p < 0.05) groups.

CONCLUSIONS

This study showed that endogenous BDNF may play a protective role in kidneys against ER stress-induced apoptosis via the suppression of GADD153. As a result, BDNF and related signaling pathways could be considered for therapeutic/protective approaches in kidney disorders.

GSTO1 acts as a mediator in sodium fluoride-induced alterations of learning and memory related factors expressions in the hippocampus cell line

The mechanism of GSTO1, as a high-risk factor for neurological damage, in sodium fluoride (NaF)-induced learning and memory impairment remained still unclear. Hence, in this study, we used the siRNA-GSTO1 HT22 model to explore the effect of NaF and siRNA-GSTO1 on the viability, and proliferation rate of HT22 cells, as well as the mRNA and protein expression levels of cyclic adenosine monophosphate (cAMP) response element binding protein (CREB), neural cell adhesion molecule (NCAM), stem cell factor (SCF) and brain-derived neurotrophic factor (BDNF). The results of MTT showed that 10^-3, 10^-4, and 10^-5 moL/L sodium fluoride (NaF) exposure could significantly promote the proliferation of HT22 cells at 24 h, 36 h, and 48 h, respectively. In addition, our results showed that exposure to 10^-3, 10^-4, and 10^-5 moL/l NaF increased GSTO1 mRNA and protein expression, but decreased CREB and BDNF expression levels in a dose and time-dependent manner. The mRNA and protein expressions of GSTO1, CREB and BDNF were significantly decreased in the siRNA-GSTO1 and NaF + siRNA-GSTO1 group (P < 0.05). We have shown that various NaF doses affected the learning and memory ability by down-regulation the expressions of CREB, BDNF, NCAM and SCF. In summary, we concluded that GSTO1 plays a mediator role in NaF-induced neurological damage.

Peritoneal endometriosis induces time-related depressive- and anxiety-like alterations in female rats: involvement of hippocampal pro-oxidative and BDNF alterations

Endometriosis is a gynecological condition affecting 10% of women in reproductive age. High rates of depression and anxiety are observed in these patients. The mechanisms underlying endometriosis-induced behavioral alterations are still elusive. Animal models provide a useful tool to study the temporal sequence and biological pathways involved in this disease and comorbid states. Here, we sought to characterize time-related behavioral alterations in rats submitted to endometriosis model (EM) induced by peritoneal auto-transplantation of uterine tissues weekly for three weeks. Corticosterone stress reactivity, oxidative stress markers - reduced glutathione (GSH), lipid peroxidation, activity of superoxide dismutase (SOD) and myeloperoxidase (MPO) - and brain-derived-neurotrophic factor (BDNF) levels in the hippocampus were also evaluated. We observed a progressive increase in anxiety-like behavior from 14th to 21st days post-EM. Despair-like behavior was observed from the 14th day post-EM on, while anhedonia and apathetic-like behaviors accompanied by increased corticosterone stress response were detected on 21 days post-EM. Increased pain sensitivity was observed from the 7th day post-EM and was accompanied by increased endometrioma weight. The pro-oxidative alterations, decreased GSH and increased SOD activity were observed on 21 days post-EM, except for lipid peroxidation that was altered from the 14th day. Decreased BDNF also occurred on the 21st day. Therefore, this study demonstrates that EM is related to several features of clinical depression and proposes the contribution of hippocampal oxidative state and neurotrophic support for the emergence of these changes. Our results support the use of this model as a useful tool to test new strategies for endometriosis-related neuropsychiatric symptoms.

Effect of lurasidone vs olanzapine on neurotrophic biomarkers in unmedicated schizophrenia: A randomized controlled trial

Neurotrophic factors like Brain-Derived Neurotrophic Factor (BDNF), Neurotrophin 3 (NT3) and Nerve Growth Factor (NGF), play a role in neuroplasticity and neurogenesis contributing to the pathogenesis of schizophrenia. The objective of the present study was to investigate and compare the effect of olanzapine and lurasidone on the change in serum neurotrophins in patients with schizophrenia. The present study was a randomized, open-label, active-controlled, parallel design clinical trial. After randomization baseline evaluations of serum BDNF, NGF, NT3, Positive and Negative Syndrome Scale (PANSS) scoring, Social and Occupational Functioning Assessment Scale (SOFAS) scoring of 101 unmedicated schizophrenia patients were done. Patients were reassessed after 6 weeks of monotherapy with olanzapine or lurasidone. Serum BDNF increased after treatment with both the drug groups but rise with olanzapine was found to be significantly higher (916.22; 95 %CI: 866.07 to 966.37; p < 0.001) in comparison to lurasidone. Increase in levels NGF and NT3 was also observed but there was no significant difference between the groups (NGF: 2.32; CI: 3.54 to -3.53; p = 0.57 and NT3: 0.99; CI: 2.11 to 0.14; p = 0.086). The difference in improvement in PANSS and SOFASS with both the drugs was not statistically significant. Both the drugs alleviate the symptoms of schizophrenia but olanzapine was better tolerated. Our findings suggest that increase in serum BDNF with olanzapine monotherapy is significantly higher than that with lurasidone but there is no significant difference in change in serum NGF and NT3. TRIAL REGISTRATION: ClinicalTrials.gov identifier: (NCT03304457).

Dysregulation of the SNARE-binding protein Munc18-1 impairs BDNF secretion and synaptic neurotransmission: a novel interventional target to protect the aging brain

Brain-derived neurotrophic factor (BDNF) has a central role in maintaining and strengthening neuronal connections and to stimulate neurogenesis in the adult brain. Decreased levels of BDNF in the aging brain are thought to usher cognitive impairment. BDNF is stored in dense core vesicles and released through exocytosis from the neurites. The exact mechanism for the regulation of BDNF secretion is not well understood. Munc18-1 (STXBP1) was found to be essential for the exocytosis of synaptic vesicles, but its involvement in BDNF secretion is not known. Interestingly, neurons lacking munc18-1 undergo severe degeneration in knock-out mice. Here, we report the effects of BDNF treatment on the presynaptic terminal using munc18-1-deficient neurons. Reduced expression of munc18-1 in heterozygous (+/-) neurons diminishes synaptic transmitter release, as tested here on individual synaptic connections with FM1-43 fluorescence imaging. Transduction of cultured neurons with BDNF markedly increased BDNF secretion in wild-type but was less effective in munc18-1 +/- cells. In turn, BDNF enhanced synaptic functions and restored the severe synaptic dysfunction induced by munc18-1 deficiency. The role of munc18-1 in the synaptic effect of BDNF is highlighted by the finding that BDNF upregulated the expression of munc18-1 in neurons, consistent with enhanced synaptic functions. Accordingly, this is the first evidence showing the functional effect of BDNF in munc18-1 deficient synapses and about the direct role of munc18-1 in the regulation of BDNF secretion. We propose a molecular model of BDNF secretion and discuss its potential as therapeutic target to prevent cognitive decline in the elderly.

Brain-derived neurotrophic factor (BDNF) is expressed in buffalo (Bubalus bubalis) ovarian follicles and promotes oocyte maturation and early embryonic development

Brain-derived neurotrophic factor (BDNF) has been discovered and characterized for several decades, yet its expression pattern in non-neuronal tissues like ovary and potential mechanism during oocyte maturation are still poorly understood. Thus the present study was devised to determine the expression pattern and mechanism of BDNF during buffalo oocyte maturation. The results revealed that BDNF was presented at different stages of buffalo ovarian follicles as well as during oocyte maturation and early embryo development. BDNF's receptor p75 was detected in granulosa cells, cumulus cells, oocytes, and early embryos, while another receptor neurotrophic tyrosine kinase receptor, type2 (NTRK2) was only identified in granulosa cells and cumulus cells. To determine the effect of BDNF on oocyte maturation and early embryo development, different concentrations (0, 1, 10, 100 ng/mL) of BDNF were added into the in vitro maturation media, respectively. It was divulged that 10 ng/mL BDNF promoted the in vitro maturation rate of buffalo oocytes and the blastocysts rate of embryos cultured in vitro (P < 0.05). Then through using NTRK2 inhibitor K-252a, we found BDNF and its receptor NTRK2 in cumulus cells played an essential role during oocyte maturation. Moreover, to further investigate the underlying mechanism by which BDNF enhances oocyte maturation, RT-qPCR was performed. 10 ng/mL BDNF treatment could decrease the expression level of apoptosis-related genes CCASP9, FAS, up-regulate the expression level of receptor gene NTRK2, cell proliferation-related genes CCNB1, PCNA, gap junction-related genes GJA4, GJA1 as well as cumulus cells expansion-related genes HAS2, PTX3 and TNFAIP6 (P < 0.05). Altogether, our results showed for the first time that BDNF was expressed throughout buffalo ovarian follicle development, oocyte maturation and early embryogenesis. Furthermore, BDNF treatment could improve the efficiency of buffalo oocyte maturation through regulating genes expression in cumulus cells and then promote early embryo development.

Long-lasting antidepressant-like activity of the GPR39 zinc receptor agonist TC-G 1008

BACKGROUND

The discovery of the zinc-sensing receptor, has provided new possibilities for explaining the neurobiology of zinc. Recent studies indicate that the GPR39 zinc receptor may play an important role in the pathogenesis of depression as well as in the antidepressant mechanism of action.

METHODS

In this study we evaluated the time-course of the antidepressant response of the GPR39 agonist (TC-G 1008), imipramine, ZnCl₂ and MK-801 in the forced swim test in mice 30 min, 3 h, 6 h and 24 h after acute drug administration as well as after 14-day treatment. Zinc level was measured in serum of mice. BDNF protein level was evaluated in hippocampus following both acute and chronic TC-G 1008 treatment.

RESULTS

A single administration of the GPR39 agonist caused an antidepressant-like effect lasting up to 24 h following the injection, which is longer than the effect of imipramine, ZnCl₂ and MK-801. Chronic treatment with these compounds caused a decrease in immobility time in the FST. Serum zinc concentrations showed an increased level following chronic ZnCl₂ administration, but not following administration of TC-G 1008, imipramine or MK-801. We also observed some tendencies for increased BDNF following acute TC-G 1008 treatment.

LIMITATIONS

TC-G 1008 is new drug designed to study GPR39 therefore additional pharmacodynamic and pharmacokinetic properties in preclinical studies are required.

CONCLUSION

This study shows for the first time the long-lasting antidepressant effect of the GPR39 agonist in comparison with imipramine, ZnCl2 and MK-801. Our findings suggest that GPR39 should be considered as a target in efforts to develop new antidepressant drugs.

Enhancement of BDNF Expression and Memory by HDAC Inhibition Requires BET Bromodomain Reader Proteins

Histone deacetylase (HDAC) inhibitors may have therapeutic utility in multiple neurological and psychiatric disorders, but the underlying mechanisms remain unclear. Here, we identify BRD4, a BET bromodomain reader of acetyl-lysine histones, as an essential component involved in potentiated expression of brain-derived neurotrophic factor (BDNF) and memory following HDAC inhibition. In in vitro studies, we reveal that pharmacological inhibition of BRD4 reversed the increase in BDNF mRNA induced by the class I/IIb HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Knock-down of HDAC2 and HDAC3, but not other HDACs, increased BDNF mRNA expression, whereas knock-down of BRD4 blocked these effects. Using dCas9-BRD4, locus-specific targeting of BRD4 to the BDNF promoter increased BDNF mRNA. In additional studies, RGFP966, a pharmacological inhibitor of HDAC3, elevated BDNF expression and BRD4 binding to the BDNF promoter, effects that were abrogated by JQ1 (an inhibitor of BRD4). Examining known epigenetic targets of BRD4 and HDAC3, we show that H4K5ac and H4K8ac modifications and H4K5ac enrichment at the BDNF promoter were elevated following RGFP966 treatment. In electrophysiological studies, JQ1 reversed RGFP966-induced enhancement of LTP in hippocampal slice preparations. Last, in behavioral studies, RGFP966 increased subthreshold novel object recognition memory and cocaine place preference in male C57BL/6 mice, effects that were reversed by cotreatment with JQ1. Together, these data reveal that BRD4 plays a key role in HDAC3 inhibitor-induced potentiation of BDNF expression, neuroplasticity, and memory.SIGNIFICANCE STATEMENT Some histone deacetylase (HDAC) inhibitors are known to have neuroprotective and cognition-enhancing properties, but the underlying mechanisms have yet to be fully elucidated. In the current study, we reveal that BRD4, an epigenetic reader of histone acetylation marks, is necessary for enhancing brain-derived neurotrophic factor (BDNF) expression and improved memory following HDAC inhibition. Therefore, by identifying novel epigenetic regulators of BDNF expression, these data may lead to new therapeutic targets for the treatment of neuropsychiatric disorders.

Astrocyte-Conditioned Medium Protects Prefrontal Cortical Neurons from Glutamate-Induced Cell Death by Inhibiting TNF-α Expression

OBJECTIVE

Both excitotoxicity and neurotrophin deficiency may contribute to the etiology of depression and neurodegeneration. Astrocytes not only regulate glutamate metabolism and clearance, they also produce neurotrophins in the brain. However, the direct interaction between neurons and astrocytes remains unknown.

METHODS

This study evaluated the cellular mechanisms by which astrocyte-conditioned medium (ACM) protects prefrontal cortical neurons from glutamate-induced death by measuring cell viability and morphology as well as mRNA and protein expression of brain-derived neurotrophic factor (BDNF), BDNF receptors, glial cell line-derived neurotrophic factor (GDNF), and the proinflammatory cytokine, tumor necrosis factor (TNF)-α. Neurons and astrocytes were purified from the brains of neonatal 1-day-old Sprague-Dawley rats. ACM was harvested after exposing astrocytes to culture medium containing 100 μM glutamate for 48 h.

RESULTS

Glutamate insult (100 μM for 6 h) significantly reduced neuronal cell viability and increased the mRNA expression of BDNF. Glutamate (24 h) decreased neuronal viability and the expression of BDNF, but increased mRNA expression of GFAP, p75 neurotrophin receptor (p75NTR), and TNF-α. ACM pretreatment (2 h) reversed glutamate-decreased cell viability and increased BDNF, but reduced the expression of GDNF, P75NTR, and TNF-α at the mRNA level. Western blotting generally confirmed the mRNA expression following 24 glutamate insults. Furthermore, the glutamate-induced decrease in the protein expression of BDNF and full-length TrkB receptor and increase in pro-BDNF, truncated TrkB isoform 1 receptor, p75NTR, GDNF, and TNF-α were significantly attenuated by ACM pretreatment.

CONCLUSIONS

The study demonstrates that ACM exerts neuroprotective effects on cell viability, and this effect is most likely mediated through the modulation of neurotrophin and TNF-α expression.

Effects of Subanesthetic Intravenous Ketamine Infusion on Corticosterone and Brain-Derived Neurotrophic Factor in the Plasma of Male Sprague-Dawley Rats

Posttrauma anesthetic agents influence neuroendocrine responses that may affect fear memory. The effects of a subanesthetic intravenous (IV) ketamine infusion on mediators of stress and memory in rodents are unknown. Therefore, we used a clinically relevant method to administer a 2-hour subanesthetic IV ketamine infusion following a rodent fear-conditioning paradigm (paired tone plus foot shock) to evaluate the effects on corticosterone and brain-derived neurotrophic factor in the plasma of male Sprague-Dawley rats. We found that subanesthetic ketamine infusions (5 and 20 mg/kg/h) dose-dependently increased plasma corticosterone levels. Ketamine at 20 mg/kg/h significantly reduced plasma brain-derived neurotrophic factor measured 2 hours after the conclusion of the ketamine infusion. These results demonstrate that a subanesthetic IV ketamine infusion maintained a heightened neuroendocrine stress response after fear conditioning and reduced levels of a neurotrophin associated with memory, which may influence fear memory processing. The behavioral outcomes of these effects are unknown and warrant future investigation.

Schisandra chinensis Fructus and Its Active Ingredients as Promising Resources for the Treatment of Neurological Diseases

Neurological diseases (NDs) are a leading cause of death worldwide and tend to mainly affect people under the age of 50. High rates of premature death and disability caused by NDs undoubtedly constrain societal development. However, effective therapeutic drugs and methods are very limited. Schisandra chinensis Fructus (SCF) is the dry ripe fruit of Schisandra chinensis (Turcz.) Baill, which has been used in traditional Chinese medicine for thousands of years. Recent research has indicated that SCF and its active ingredients show a protective role in NDs, including cerebrovascular diseases, neurodegenerative diseases, or depression. The key neuroprotective mechanisms of SCF and its active ingredients have been demonstrated to include antioxidation, suppression of apoptosis, anti-inflammation, regulation of neurotransmitters, and modulation of brain-derived neurotrophic factor (BDNF) related pathways. This paper summarizes studies of the role of SCF and its active ingredients in protecting against NDs, and highlights them as promising resources for future treatment. Furthermore, novel insights on the future challenges of SCF and its active ingredients are offered.

The effects of vitamin E on brain derived neurotrophic factor, tissues oxidative damage and learning and memory of juvenile hypothyroid rats

The effects of vitamin E (Vit E) on brain derived neurotrophic factor (BDNF) and brain tissues oxidative damage as well as on learning and memory impairments in juvenile hypothyroid rats were examined. The rats were grouped as: (1) Control; (2) Propylthiouracil (PTU); (3) PTU-Vit E and (4) Vit E. PTU was added to their drinking water (0.05%) during 6 weeks. Vit E (20 mg/kg) was daily injected (IP). Morris water maze (MWM) and passive avoidance (PA) were carried out. The animals were deeply anesthetized and the brain tissues were removed for biochemical measurements. PTU increased the escape latency and traveled path in MWM (P < 0.001). It also shortened the latency to enter the dark compartment of PA as well as the time spent in the target quadrant in probe trial of MWM (P < 0.01-P < 0.001). All the effects of PTU were reversed by Vit E (P < 0.01-P < 0.001). PTU administration attenuated thiol and BDNF content as well as the activities of superoxide dismutase (SOD) and catalase (CAT) in the brain tissues while increased molondialdehyde (MDA). Moreover, Vit E improved BDNF, thiol, SOD and CAT while diminished MDA. The results of the present study showed that Vit E improved BDNF and prevented from brain tissues oxidative damage as well as learning and memory impairments in juvenile hypothyroid rats.

Effect of quercetin on the brain-derived neurotrophic factor gene expression in the rat brain

INTRODUCTION

Quercetin is a ubiquitous flavonoid found in many plants. Neuroprotective effects of quercetin have been shown in several in vitro and in vivo studies, but its mechanism of action has not been fully defined yet. Brain-derived neurotrophic factor (BDNF) is a fundamental neurotrophin with vital functions in the survival of neuronal cells. In the present study, we aimed to investigate the effects of quercetin on expression of BDNF mRNA in the hippocampus of rat brain.

METHODS

Male rats were daily gavaged with quercetin (10, 20 or 50 mg/kg·bwt) for 30 days. Hippocampal levels of the BDNF transcripts were assessed using quantitative (q) RT-PCR.

RESULTS

Quercetin at doses of 20 and 50 mg/kg caused a significant increase in the mRNA expression of BDNF as compared with the control group. Quercetin treatment at a dose of 10 mg/kg failed to cause any significant changes in the levels of BDNF mRNA CONCLUSION: Our findings suggest that the neuroprotective effects of quercetin may be at least partly due to its inducing effects on the expression levels of the BDNF mRNA (Fig. 1, Ref. 40).

Minocycline restores cognitive-relative altered proteins in young bile duct-ligated rat prefrontal cortex

AIMS

Bile duct ligation (BDL) model is used to study hepatic encephalopathy accompanied by cognitive impairment. We employed the proteomic analysis approach to evaluate cognition-related proteins in the prefrontal cortex of young BDL rats and analyzed the effect of minocycline on these proteins and spatial memory.

MAIN METHODS

BDL was induced in young rats at postnatal day 17. Minocycline as a slow-release pellet was implanted into the peritoneum. Morris water maze test and two-dimensional liquid chromatography-tandem mass spectrometry were used to evaluate spatial memory and prefrontal cortex protein expression, respectively. We used 2D/LC-MS/MS to analyze for affected proteins in the prefrontal cortex of young BDL rats. Results were verified with Western blotting, immunohistochemistry, and quantitative real-time PCR. The effect of minocycline in BDL rats was assessed.

KEY FINDINGS

BDL induced spatial deficits, while minocycline rescued it. Collapsin response mediator protein 2 (CRMP2) and manganese-dependent superoxide dismutase (MnSOD) were upregulated and nucleoside diphosphate kinase B (NME2) was downregulated in young BDL rats. BDL rats exhibited decreased levels of brain-derived neurotrophic factor (BDNF) mRNA as compared with those by the control. However, minocycline treatment restored CRMP2 and NME2 protein expression, BDNF mRNA level, and MnSOD activity to control levels.

SIGNIFICANCE

We demonstrated that BDL altered the expression of CRMP2, NME2, MnSOD, and BDNF in the prefrontal cortex of young BDL rats. However, minocycline treatment restored the expression of the affected mediators that are implicated in cognition.

17β-Estradiol augments antidepressant efficacy of escitalopram in ovariectomized rats: Neuroprotective and serotonin reuptake transporter modulatory effects

The prevalence or recurrence of depression is seriously increased in women during the transition to and after menopause. The chronic hypo-estrogenic state of menopause may reduce the response to antidepressants; however the influence of estrogen therapy on their efficacy is still controversial. This study aimed at investigating the effects of combining escitalopram with 17β-estradiol on depression and cognitive impairment induced by ovariectomy, an experimental model of human menopause. Young adult female Wistar rats were subjected to either sham operation or ovariectomy. Ovariectomized animals were treated chronically with escitalopram (10mg/kg/day, i.p) alone or with four doses of 17β-estradiol (40μg/kg, s.c) given prior to the behavioral tests. Co-administration of 17β-estradiol improved escitalopram-induced antidepressant effect in forced swimming test verified as more prominent decrease in the immobility time without opposing its memory enhancing effect in Morris water maze. 17β-estradiol augmented the modulatory effects of escitalopram on the hippocampal levels of brain-derived neurotrophic factor and serotonin reuptake transporter as well as tumor necrosis factor-alpha without altering its effects on the gene expressions of serotonin receptor 1A, estrogen receptors alpha and beta, or acetylcholinestearase content. This combined therapy afforded synergistic protective effects on the brain histopathological architecture, particularly, the hippocampus. The antidepressant effect of 17β-estradiol was abolished by pretreatment with estrogen receptor antagonist, tamoxifen (10mg/kg, p.o). In conclusion, 17β-estradiol-induced antidepressant effect was confined to intracellular estrogen receptors activation. Moreover, 17β-estradiol enhanced escitalopram's efficiency in ameliorating menopausal-like depression, via exerting synergistic neuroprotective and serotonin reuptake transporter modulatory effects, without impeding escitalopram-mediated cognitive improvement.

Contingent and non-contingent recreational-like exposure to ethanol alters BDNF expression and signaling in the cortico-accumbal network differently

RATIONALE

Although brain-derived neurotrophic factor (BDNF) is part of a homeostatic pathway involved in the development of alcohol dependence, it is not clear whether this is also true after recreational ethanol consumption.

OBJECTIVES

We examined BDNF expression and signaling in the cortico-striatal network immediately and 24 h after either a single intravenous (i.v.) ethanol operant self-administration session or the last of 14 sessions.

METHODS

To compare contingent and non-contingent ethanol exposure, we incorporated the "yoked control-operant paradigm" in which rats actively taking ethanol (S-Et) were paired with two yoked controls receiving passive infusions of ethanol (Y-Et) or saline.

RESULTS

A single ethanol exposure transiently reduced BDNF mRNA levels in the medial prefrontal cortex (mPFC) of Y-Et. Immediately after the last of 14 sessions, mRNA and mature BDNF protein levels (mBDNF) were reduced in the mPFC in both S-Et and Y-Et while mBDNF expression was raised in the nucleus accumbens (NAc), suggesting enhanced anterograde transport from the mPFC. Conversely, 24 h later mBDNF expression and signaling were raised in the mPFC and NAc of S-Et rats but reduced in the NAc of Y-Et rats, with concomitant reduction of downstream signaling pathways.

CONCLUSIONS

Our findings indicate that recreational-like i.v. doses of ethanol promote early changes in neurotrophin expression, depending on the length and modality of administration, the brain region investigated, and the presence of the drug. A rapid intervention targeting the BDNF system might be useful to prevent escalation to alcohol abuse.

n-3 Fatty Acids Induce Neurogenesis of Predominantly POMC-Expressing Cells in the Hypothalamus

Apoptosis of hypothalamic neurons is believed to play an important role in the development and perpetuation of obesity. Similar to the hippocampus, the hypothalamus presents constitutive and stimulated neurogenesis, suggesting that obesity-associated hypothalamic dysfunction can be repaired. Here, we explored the hypothesis that n-3 polyunsaturated fatty acids (PUFAs) induce hypothalamic neurogenesis. Both in the diet and injected directly into the hypothalamus, PUFAs were capable of increasing hypothalamic neurogenesis to levels similar or superior to the effect of brain-derived neurotrophic factor (BDNF). Most of the neurogenic activity induced by PUFAs resulted in increased numbers of proopiomelanocortin but not NPY neurons and was accompanied by increased expression of BDNF and G-protein-coupled receptor 40 (GPR40). The inhibition of GPR40 was capable of reducing the neurogenic effect of a PUFA, while the inhibition of BDNF resulted in the reduction of global hypothalamic cell. Thus, PUFAs emerge as a potential dietary approach to correct obesity-associated hypothalamic neuronal loss.

Mild Thyroid Hormone Insufficiency During Development Compromises Activity-Dependent Neuroplasticity in the Hippocampus of Adult Male Rats

Severe thyroid hormone (TH) deficiency during critical phases of brain development results in irreversible neurological and cognitive impairments. The mechanisms accounting for this are likely multifactorial, and are not fully understood. Here we pursue the possibility that one important element is that TH affects basal and activity-dependent neurotrophin expression in brain regions important for neural processing. Graded exposure to propylthiouracil (PTU) during development produced dose-dependent reductions in mRNA expression of nerve growth factor (Ngf) in whole hippocampus of neonates. These changes in basal expression persisted to adulthood despite the return to euthyroid conditions in blood. In contrast to small PTU-induced reductions in basal expression of several genes, developmental PTU treatment dramatically reduced the activity-dependent expression of neurotrophins and related genes (Bdnft, Bdnfiv, Arc, and Klf9) in adulthood and was accompanied by deficits in hippocampal-based learning. These data demonstrate that mild TH insufficiency during development not only reduces expression of important neurotrophins that persists into adulthood but also severely restricts the activity-dependent induction of these genes. Considering the importance of these neurotrophins for sculpting the structural and functional synaptic architecture in the developing and the mature brain, it is likely that TH-mediated deficits in these plasticity mechanisms contribute to the cognitive deficiencies that accompany developmental TH compromise.

Doxorubicin and cyclophosphamide induce cognitive dysfunction and activate the ERK and AKT signaling pathways

Chemotherapy is associated with long-term cognitive deficits in breast cancer survivors. Studies suggest that these impairments result in the loss of cognitive reserve and/or induce a premature aging of the brain. This study has been aimed to determine the potential underlying mechanisms that induce cognitive impairments by chemotherapeutic agents commonly used in breast cancer. Intact and ovariectomized (OVX) female rats were treated intravenously with either saline or a combination of cyclophosphamide (40 mg/kg) and doxorubicin (4 mg/kg). All subjects were tested for anxiety, locomotor activity, working, visual and spatial memory consecutively. Although anxiety and visual memory were not affected, chemotherapy significantly decreased locomotor activity and impaired working and spatial memory in female rats, independent of their hormonal status. The cognitive deficits observed are hippocampal dependent. Therefore, as a first step to identity the potential signaling pathways involved in this cognitive dysfunction, the protein levels of extracellular signal-regulated kinase 1/2 (Erk1/2), Akt (neuroprotectant) BDNF and (structural protein) PSD95 in hippocampal lysates were measured. Erk1/2 and Akt pathways are known to modulate synaptic plasticity, neuronal survival, aging and cancer. We found an increased activation of Erk1/2 and Akt as well as an increase in the protein levels of PSD95 in OVX female rodents. However, OVX females had a higher overall BDNF level, independent of chemotherapy. These studies provide additional evidence that commonly used chemotherapeutic agents affect cognitive function and impact synaptic plasticity/aging molecules which may be part of the underlying biology explaining cognitive change and can be potential therapeutic targets.

Inhaled β-agonist does not modify sympathetic activity in patients with COPD

BACKGROUND

Neurohumoral activation is present in COPD and might provide a link between pulmonary and systemic effects, especially cardiovascular disease. Because long acting inhaled β-agonists reduce hyperinflation, they could reduce sympathoexcitation by improving the inflation reflex. We aimed to evaluate if inhaled therapy with salmeterol reduces muscle sympathetic nerve activity (MSNA) evaluated by microneurography.

METHODS

MSNA, heart rate, blood pressure, and respiration were continually measured. After baseline recording of 20 minutes, placebo was administered; after further 45 minutes salmeterol (50 μg) was administered which was followed by a further 45 minutes of data recording. Additionally, lung function, plasma catecholamine levels, arterial pulse wave velocity, heart rate variability, and baroreflex sensitivity were evaluated. Following 4 weeks of treatment with salmeterol 50 μg twice daily, measurements were repeated without placebo administration.

RESULTS

A total of 32 COPD patients were included. Valid MSNA signals were obtained from 18 patients. Change in MSNA (bursts/100 heart beats) following acute administration of salmeterol did not differ significantly from the change following placebo (-1.96 ± 9.81 vs. -0.65 ± 9.07; p = 0.51) although hyperinflation was significantly reduced. Likewise, no changes in MSNA or catecholamines were observed after 4 weeks. Heart rate increased significantly by 3.8 ± 4.2 (p < 0.01) acutely and 3.9 ± 4.3 bpm (p < 0.01) after 4 weeks. Salmeterol treatment was safe and well tolerated.

CONCLUSIONS

By using microneurography as a gold standard to evaluate sympathetic activity we found no change in MSNA following salmeterol inhalation. Thus, despite an attenuation of hyperinflation, the long acting β-agonist salmeterol does not appear to reduce nor incite sympathoexcitation.

TRIAL REGISTRATION

This study was registered with the European Clinical Trials Database (EudraCT No. 2011-001581-18) and ClinicalTrials.gov ( NCT01536587 ).

Flavonoid Chrysin prevents age-related cognitive decline via attenuation of oxidative stress and modulation of BDNF levels in aged mouse brain

In this study, the effect of Chrysin (5,7-dihydroxyflavone), an important member of the flavonoid family, on memory impairment, oxidative stress and BDNF reduction generated by aging in mice were investigated. Young and aged mice were treated daily per 60days with Chrysin (1 and 10mg/kg; per oral, p.o.) or veichle (10ml/kg; p.o.). Mice were trained and tested in Morris Water Maze task. After the behavioural test, the levels of reactive species (RS), the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as the activity of Na(+), K(+)-ATPase and the levels of brain-derived neurotrophic factor (BDNF) were determined in the prefrontal cortex (PFC) and hippocampus (HC) of mice. Results demonstrated that the age-related memory decline was partially protected by Chrysin at a dose of 1mg/kg, and normalized at the dose of 10mg/kg (p<0.001). Treatment with Chrysin significantly attenuated the increase of RS levels and the inhibition of SOD, CAT and GPx activities of aged mice. Inhibition of Na(+), K(+)-ATPase activity in PFC and HP of aged mice was also attenuated by Chrysin treatment. Moreover, Chrysin marked mitigated the decrease of BDNF levels in the PFC and HC of aged mice. These results demonstrated that flavonoid Chrysin, an antioxidant compound, was able to prevent age-associated memory probably by their free radical scavenger action and modulation of BDNF production. Thus, this study indicates that Chrysin may represent a new pharmacological approach to alleviate the age-related declines during normal age, acting as an anti-aging agent.

Effect of Tenuifoliside A isolated from Polygala tenuifolia on the ERK and PI3K pathways in C6 glioma cells

Tenuifoliside A (TFSA) is a bioactive oligosaccharide ester component of Polygala tenuifolia Wild, a traditional Chinese medicine which was used to manage mental disorders effectively. The neuroprotective and anti-apoptotic effects of TFSA have been demonstrated in our previous studies. The present work was designed to study the molecular mechanism of TFSA on promoting the viability of rat glioma cells C6. We exposed C6 cells to TFSA (or combined with ERK, PI3K and TrkB inhibitors) to examine the effects of TFSA on the cell viability and the expression and phosphorylation of key proteins in the ERK and PI3K signaling pathway. TFSA increased levels of phospho-ERK and phospho-Akt, enhanced release of BDNF, which were blocked by ERK and PI3K inhibitors, respectively (U0126 and LY294002). Moreover, the TFSA caused the enhanced phosphorylation of cyclic AMP response element binding protein (CREB) at Ser133 site, the effect was revoked by U0126, LY294002 and K252a. Furthermore, when C6 cells were pretreated with K252a, a TrkB antagonist, known to significantly inhibit the activity of brain-derived neurotrophic factor (BDNF), blocked the levels of phospho-ERK, phospho-Akt and phosphor-CREB. Taking these results together, we suggested the neuroprotection of TFSA might be mediated through BDNF/TrkB-ERK/PI3K-CREB signaling pathway in C6 glioma cells.

Dietary omega-3 deficiency reduces BDNF content and activation NMDA receptor and Fyn in dorsal hippocampus: implications on persistence of long-term memory in rats

Omega-3 (n-3) fatty acids are important for adequate brain function and cognition. The aim of the present study was to evaluate how n-3 fatty acids influence the persistence of long-term memory (LTM) in an aversive memory task and to explore the putative mechanism involved. Female rats received isocaloric diets that included n-3 (n-3 group) or not (D group). The adult litters were subjected to an inhibitory avoidance task (0.7 mA, 1.0 seconds foot shock) to elicit persistent LTM. Twelve hours after the training session, the fatty acid profile and the brain derived neurotrophic factor (BDNF) content of the dorsal hippocampus were assessed. In addition, we measured the activation of the NR2B subunit of the N-methyl-d-aspartate (NMDA) receptor and the SRC family protein Fyn. Despite pronounced learning in both groups, the persistence of LTM was abolished in the D group 7 days after the training session. We also observed that the D group presented reductions in hippocampal DHA (22:6 n-3) and BDNF content. Twelve hours after the training session, the D group showed decreased NR2B and Fyn phosphorylation in the dorsal hippocampus, with no change in the total content of these proteins. Further, there was a decrease in the interaction of Fyn with NR2B in the D group, as observed by co-immunoprecipitation. Taken together, these data suggest that n-3 fatty acids influence the persistence of LTM by maintaining adequate levels of DHA and BDNF as well as by influencing the activation of NR2B and Fyn during the period of memory formation.

Prenatal omega 3 fatty acid supplementation to a micronutrient imbalanced diet protects brain neurotrophins in both the cortex and hippocampus in the adult rat offspring

OBJECTIVE

Our earlier studies show that maternal diets imbalanced in micronutrients like folic acid and vitamin B12 reduced brain docosahexaenoic acid (DHA) and brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in the offspring at birth and postnatal d21. This study followed the offspring till 3 months to examine the hypothesis that impaired brain neurotrophins at birth and d21 due to altered maternal micronutrients can be reversed by prenatal omega 3 fatty acid but not a postnatal control diet leading to altered cognition in adult life.

MATERIALS AND METHODS

Pregnant rats were divided into control and five treatment groups at two levels of folic acid (normal and excess folate) in the presence and absence of vitamin B12 (NFBD, EFB and EFBD). Omega 3 fatty acid supplementation was given to the vitamin B12 deficient groups (NFBDO and EFBDO). Following delivery, 8 dams from each group were shifted to control and remaining continued on same diet.

RESULTS

Imbalance in maternal micronutrients up to 3months decreased DHA, BDNF and NGF in cortex and only BDNF in the hippocampus and impaired cognitive performance. Postnatal control diet normalized BDNF in the cortex but not the hippocampus and also altered cognitive performance. Prenatal omega 3 fatty acid supplementation normalized DHA, BDNF and NGF while long term supplementation was not beneficial only when micronutrients were imbalanced.

CONCLUSION

Patterns established at birth are not totally reversible by postnatal diets and give clues for planning intervention studies for improving brain functioning and cognitive abilities.

[Study on antidepressant effect of kuanxinjieyutang combined aerobic exercise]

OBJECTIVE

To observe antidepressant effects of Kuanxinjieyutang (KXJYT), short-term aerobic exercise and their joint intervention and its possible mechanism.

METHODS

Ninty-six SPF male KM mice were randomly divided into control group, imipramine, low dose (KXJYT 1.8 g crude drugs/kg bw/time/day), high dose (3.6 g crude drugs/kg bw/time/day), exercise group (swimming 30 min/times/day), joint group (low dose and swimming ), with 8 days intervention. The antidepressant effect was evaluated by forced swimming, tail suspension test and overhead cross maze test. After mice were killed, brain monoamine neurotransmitter levels of mice were detected by ELISA, and BDNF expression in brain was analyzed by Western blotting.

RESULTS

High dose group showed antidepressant effect like imipramine while low dose didn't. Exercise group showed similar or better antidepressant effect than imipramine. Joint group showed better interaction antidepressant effect. Brain NE, DA of high dose group and brain NE, DA and 5-HT content of exercise group increased significantly, similar to imipramine. Brain NE,DA and 5-HT content of Joint group were significantly higher than those of imipramine. The protein expression of BDNF in brain was more in imipramine, high dose,exercise and joint groups than that of control group, sports group was higher than that of low dose and high dose group, joint group was obviously higher than other groups.

CONCLUSION

Moderate KXJYT, short-term aerobic exercise and their joint intervention have obvious antidepressant effect on mild depression. Its mechanism may be related to increasing brain NE and 5-HT content, and inducing brain BDNF expression, which may affect the nerve regeneration and plasticity, improve cognitive function.

Exercise and sodium butyrate transform a subthreshold learning event into long-term memory via a brain-derived neurotrophic factor-dependent mechanism

We demonstrate that exercise enables hippocampal-dependent learning in conditions that are normally subthreshold for encoding and memory formation, and depends on hippocampal induction of brain-derived neurotrophic factor (BDNF) as a key mechanism. Using a weak training paradigm in an object location memory (OLM) task, we show that sedentary mice are unable to discriminate 24 h later between familiar and novel object locations. In contrast, 3 weeks of prior voluntary exercise enables strong discrimination in the spatial memory task. Cognitive benefits of exercise match those attained with post-training sodium butyrate (NaB), a histone deacetylase (HDAC) inhibitor previously shown to enable subthreshold learning. We demonstrate that the enabling effects of exercise and NaB on subthreshold OLM learning are dependent on hippocampal BDNF upregulation, and are blocked by hippocampal infusion of BDNF short-interfering RNA. Exercise and NaB increased bdnf transcripts I and IV, and the increases were associated with BDNF promoter acetylation on H4K8 but not H4K12. These data provide support for the concept that exercise engages epigenetic control mechanisms and serves as a natural stimulus that operates in part like NaB and potentially other HDAC inhibitors, placing the brain into a state of readiness for plasticity.

Ketamine, sleep, and depression: current status and new questions

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has well-described rapid antidepressant effects in clinical studies of individuals with treatment-resistant major depressive disorder (MDD). Preclinical studies investigating the effects of ketamine on brain-derived neurotrophic factor (BDNF) and on sleep slow wave activity (SWA) support its use as a prototype for investigating the neuroplastic mechanisms presumably involved in the mechanism of rapidly acting antidepressants. This review discusses human EEG slow wave sleep parameters and plasma BDNF as central and peripheral surrogate markers of plasticity, and their use in assessing ketamine's effects. Acutely, ketamine elevates BDNF levels, as well as early night SWA and high-amplitude slow waves; each of these measures correlates with change in mood in depressed patients who respond to ketamine. The slow wave effects are limited to the first night post-infusion, suggesting that their increase is part of an early cascade of events triggering improved mood. Increased total sleep and decreased waking occur during the first and second night post infusion, suggesting that these measures are associated with the enduring treatment response observed with ketamine.

Brain derived neurotrophic factor (BDNF) levels in depressed women treated with open-label escitalopram

BACKGROUND

Recent studies suggest the important role of brain derived neurotrophic factor (BDNF) in the etiopathogenesis of major depressive disorder (MDD) and the mechanism of action of antidepressants. This study aimed to correlate serum levels of BDNF and clinical symptoms in patients with MDD before and after 6 months treatment with escitalopram.

SUBJECTS AND METHODS

Twenty women diagnosed with MDD and 20 aged-matched healthy female controls were recruited. The patients received escitalopram 10-20 mg/day. BDNF serum levels were measured at inclusion, week 4, week 12 and week 24. The Montgomery-Åsberg Depression Rating Scale (MADRS) was used to assess the severity of depressive symptoms and the clinical evolution of patients. Statistical analysis was performed using both observed cases and last observation carried forward.

RESULTS

At baseline, low serum levels of BDNF were associated with MDD. In women with MDD, escitalopram seems to have a positive effect on BDNF serum levels in parallel with the clinical response.

CONCLUSIONS

This study suggests that a good clinical evolution under treatment with escitalopram might be associated with increases of BDNF levels in female patients.

Different serum BDNF levels in depression: results from BDNF studies in FYR Macedonia and Bulgaria

BACKGROUND

A growing body of evidence shows that brain-derived neurotrophic factor (BDNF) plays a role in depressive disorder. Serum BDNF levels are lower in depressed patients and they increase after a long course of antidepressant treatment. Our study aims to test the effect of antidepressant treatment on serum BDNF levels in patients with a depressive episode, after they have achieved remission in two studies in Macedonia and Bulgaria.

SUBJECTS AND METHODS

In the Macedonian study 23 patients were included (11 female, 12 male) diagnosed with a first depressive episode according to ICD-10, as well as 23 control subjects age- and sex-matched without a history of psychiatric disorder. In the Bulgarian study 10 female patients with depression and 10 control subjects were included. We have applied the Hamilton Depression Rating Scale (HDRS) to assess depression severity. Blood samples were collected before antidepressive treatment and after remission was achieved (decrease to 7 points or less on HDRS).

RESULTS

In the Macedonian study, mean serum BDNF level at baseline was 13.15±6.75 ng/ml and the mean HDRS score was 28.52±4.02. Untreated depressed patients showed significantly lower serum BDNF levels compared to the control group (25.95±9.17 ng/ml). After remission was achieved, the mean serum BDNF level was 24.73±11.80 ng/ml whereas the mean HDRS score was 7.04±3.15. After 8 weeks of treatment there was no statistically significant difference in the serum BDNF levels between the two groups. In the Bulgarian study, baseline mean serum BDNF levels were 26.84±8.66 ng/ml, after 3 weeks treatment and remission was achieved mean serum BDNF levels were 30.33±9.25 ng/ml and in the control group mean serum BDNF levels were 25.04±2.88 ng/ml. Integrated results showed baseline mean serum BDNF levels of 17.30±9.66 ng/ml, after achieved remission 26.43±11.25 ng/ml and in the control group mean serum BDNF levels of 25.68±7.76 ng/ml.

CONCLUSION

The Bulgarian results showed no statistical difference between the depressed group and controls. The Integrated results and the Macedonian study supported previous findings of low BDNF levels in untreated depressive patients compared to healthy controls, and that those levels increase after antidepressant treatment. These results may suggest that low serum levels of BDNF are a state abnormality that is evident during depression and normalizes during remission.

Involvement of brain-derived neurotrophic factor in late-life depression

Brain-derived neurotrophic factor (BDNF), one of the major neurotrophic factors, plays an important role in the maintenance and survival of neurons, synaptic integrity, and synaptic plasticity. Evidence suggests that BDNF is involved in major depression, such that the level of BDNF is decreased in depressed patients and that antidepressants reverse this decrease. Stress, a major factor in depression, also modulates BDNF expression. These studies have led to the proposal of the neurotrophin hypothesis of depression. Late-life depression is associated with disturbances in structural and neural plasticity as well as impairments in cognitive behavior. Stress and aging also play a crucial role in late-life depression. Many recent studies have suggested that not only expression of BDNF is decreased in the serum/plasma of patients with late-life depression, but structural abnormalities in the brain of these patients may be associated with a polymorphism in the BDNF gene, and that there is a relationship between a BDNF polymorphism and antidepressant remission rates. This review provides a critical review of the involvement of BDNF in major depression, in general, and in late-life depression, in particular.