Prefrontal cortex modulates the correlations between brain-derived neurotrophic factor level, serotonin, and the autonomic nervous system

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response. Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region-specific, particularly involving the corticolimbic system, including the ventral tegmental area, nucleus accumbens, prefrontal cortex, amygdala, and hippocampus. Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology. In this review, we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression. We focused on associated molecular pathways and neural circuits, with special attention to the brain-derived neurotrophic factor-tropomyosin receptor kinase B signaling pathway and the ventral tegmental area-nucleus accumbens dopamine circuit. We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature, severity, and duration of stress, especially in the above-mentioned brain regions of the corticolimbic system. Therefore, BDNF might be a biological indicator regulating stress-related processes in various brain regions.

Resting heart rate (variability) and cognition relationships reveal cognitively healthy individuals with pathological amyloid/tau ratio

Introduction

Resting heart rate (HR) and heart rate variability (HRV) have been linked with cognition in the general population and in older individuals. The knowledge of this aspect of heart-brain relationship is relatively absent in older individuals with early Alzheimer's disease (AD) pathology. This study explores relationships of the HR, HRV, and cognition in cognitively healthy individuals with pathological amyloid/tau ratio (CH-PATs) in cerebral spinal fluid (CSF) compared to those with normal ratio (CH-NATs).

Methods

We examined therelationshipsbetween1) resting HR and Mini-Mental State Examination (MMSE); 2) resting HR and brain processing during Stroop interference; and 3) resting vagally mediated HRV (vmHRV) and task switching performance.

Results

Our studies showed that compared to CH-NATs, those CH-PATs with higher resting HR presented with lower MMSE, and less brain activation during interference processing. In addition, resting vmHRV was significantly correlated with task switching accuracy in CH-NATs, but not in CH-PATs.

Discussion

Thesethreedifferenttestsindicatedysfunctionalheart-brainconnections in CH-PATs, suggesting a potential cardio-cerebral dysfunctional integration.

Extract of Mallotus oppositifolius (Geiseler) Müll. Arg. increased prefrontal cortex dendritic spine density and serotonin and attenuated para-chlorophenylalanine-aggravated aggressive and depressive behaviors in mice

Background/Aim: Depression-related aggression is linked to serotonin (5-HT) and dendritic spine alterations. Although Mallotus oppositifolius extract (MOE) has potential for reducing this effect, its specific role remains uncertain. Herein, we evaluated this potential and associated alterations in the brain.

Methods: A standard resident-intruder model of para-chlorophenylalanine (pCPA)-induced depression-associated aggression in male ICR mice was used. The resident mice received pCPA (300 mg/kg, i. p.) for 3 consecutive days while saline-treated mice served as negative control. The pCPA aggressive mice were subsequently treated orally with either MOE (30, 100, 300 mg/kg), fluoxetine (20 mg/kg), tryptophan (20 mg/kg) or saline (untreated pCPA group) for 28 days. Locomotor activity was assessed using open field test. Serotonin (5-HT) levels in mice brain and phytochemical fingerprint of MOE were determined by high performance liquid chromatography (HPLC) while gas chromatography-mass spectrometry (GC-MS) was used to identify constituents of MOE. Dendritic spine density and morphology were evaluated using Golgi-Cox staining technique and analyzed with ImageJ and Reconstruct software.

Results: Administration of pCPA induced aggressive behavior in mice, evidenced by increased attack behaviors (increased number and duration of attacks), which positively correlated with squeaking and tail rattling. MOE treatment significantly reduced these characteristics of aggression in comparison with vehicle (non-aggressive) and untreated pCPA groups (p < 0.001), and also reduced social exploration behavior. Although the behavioral effects of MOE were comparable to those of fluoxetine and tryptophan, these effects were quicker compared to fluoxetine and tryptophan. Additionally, MOE also markedly increased 5-HT concentration and dendritic spine density in the prefrontal cortex relative to vehicle and untreated pCPA groups (p < 0.05). Interestingly, these behavioral effects were produced without compromising locomotor activity. GC-MS analysis of the MOE identified 17 known compounds from different chemical classes with anti-inflammatory, antioxidant, neuroprotective and antidepressant activities, which may have contributed to its anti-aggressive effect.

Conclusion: MOE decreased depression-associated aggressive behavior in mice via increased 5-HT concentration and dendritic spine density in the prefrontal cortex. The MOE-mediated effects were faster than those of fluoxetine and tryptophan. Our finding suggests that MOE may have clinical promise in decreasing aggressive and depressive behaviors.

Serotonin Modulates the Correlations between Obsessive-compulsive Trait and Heart Rate Variability in Normal Healthy Subjects: A SPECT Study with [123I]ADAM and Heart Rate Variability Measurement

Objective

The impact of serotonergic system on obsessive-compulsive disorder (OCD) is well studied. However, the correlation between OC presentations and autonomic nervous system (ANS) is still unclear. Furthermore, whether the correlation might be modulated by serotonin is also uncertain.

Methods

We recruited eighty-nine healthy subjects. Serotonin transporter (SERT) availability by [¹²³I]ADAM and heart rate variability (HRV) tests were measured. Symptoms checklist-90 was measured for the OC presentations. The interaction between HRV and SERT availability were calculated and the correlation between HRV and OC symptoms were analyzed after stratified SERT level into two groups, split at medium.

Results

The interactions were significant in the factors of low frequency (LF), high frequency (HF), and root mean square of successive differences (RMSSD). Furthermore, the significantly negative correlations between OC symptoms and the above HRV indexes existed only in subjects with higher SERT availability.

Conclusion

OC symptoms might be correlated with ANS regulations in subjects with higher SERT availability.

Theta burst stimulation over the prefrontal cortex: Effects on cerebral oximetry and cardiovascular measures in healthy humans

Theta Burst Stimulation (TBS) is a non-invasive neurophysiological technique, able to induce changes in synaptic activity. Research suggests that TBS may induce changes in cerebral oxygenation, cerebral blood flow, blood pressure and heart rate but there are conflicting results across studies. Thus, the objective of our sham-controlled study is to evaluate if TBS applied to the dorsolateral prefrontal cortex (DLPFC) of healthy volunteers produces changes in cerebral oximetry, heart rate and blood pressure. Forty-nine volunteers of both sexes were randomly allocated to one of five stimulation groups. Before and after real TBS or sham stimulation, blood pressure, heart rate, and cerebral oxygenation of the volunteers were measured. Cerebral oxygenation values were obtained with a near infra-red spectroscopy system. We found a significant reduction in left cortex oximetry after continuous TBS (cTBS) over the left DLPFC (p = 0.039) and a non-significant reduction in right cortex oximetry (p = 0.052). Right hemisphere inhibition (using cTBS) seemed to originate a significant reduction of 8 mmHg in systolic arterial pressure. No other changes were seen in oximetry, cardiac frequency and diastolic arterial pressure. In our group of normal subjects, cTBS applied to the left DLPFC was able to reduce oxygenation in the left cortex. Right hemisphere inhibition was associated with a significant reduction in systolic pressure.

The Interaction of Selective A1 and A2A Adenosine Receptor Antagonists with Magnesium and Zinc Ions in Mice: Behavioural, Biochemical and Molecular Studies

The purpose of the study was to investigate whether the co-administration of Mg²⁺ and Zn²⁺ with selective A1 and A2A receptor antagonists might be an interesting antidepressant strategy. Forced swim, tail suspension, and spontaneous locomotor motility tests in mice were performed. Further, biochemical and molecular studies were conducted. The obtained results indicate the interaction of DPCPX and istradefylline with Mg²⁺ and Zn²⁺ manifested in an antidepressant-like effect. The reduction of the BDNF serum level after co-administration of DPCPX and istradefylline with Mg²⁺ and Zn²⁺ was noted. Additionally, Mg²⁺ or Zn²⁺, both alone and in combination with DPCPX or istradefylline, causes changes in Adora1 expression, DPCPX or istradefylline co-administered with Zn²⁺ increases Slc6a15 expression as compared to a single-drug treatment, co-administration of tested agents does not have a more favourable effect on Comt expression. Moreover, the changes obtained in Ogg1, MsrA, Nrf2 expression show that DPCPX-Mg²⁺, DPCPX-Zn²⁺, istradefylline-Mg²⁺ and istradefylline-Zn²⁺ co-treatment may have greater antioxidant capacity benefits than administration of DPCPX and istradefylline alone. It seems plausible that a combination of selective A1 as well as an A2A receptor antagonist and magnesium or zinc may be a new antidepressant therapeutic strategy.

Dietary tryptophan depletion alters the faecal bacterial community structure of compulsive drinker rats in schedule-induced polydipsia

RATIONALE

Compulsive behaviour, present in different psychiatric disorders such as obsessive-compulsive disorder, schizophrenia and drug abuse, is associated with altered levels of serotonin (5-hydroxytryptamine, 5-HT). The gut microbiota regulates tryptophan (TRP) metabolism and may affect global 5-H synthesis in the enteric and central nervous systems, suggesting a possible involvement of gut microbiota in compulsive spectrum disorders.

OBJECTIVES

The present study investigated whether chronic TRP depletion by diet alters the faecal bacterial community profiles of compulsive versus non-compulsive rats in schedule-induced polydipsia (SIP). Peripheral plasma 5-HT and brain-derived neurotrophic factor (BDNF) levels were evaluated.

METHODS

Wistar rats were selected as High Drinkers (HD) or Low Drinkers (LD) according to their SIP behaviour and were fed for 14 days with either a TRP-free diet (T-) or a TRP-supplemented diet (T+). The faecal bacterial community structure was investigated with 16S rRNA gene-targeted denaturing gradient gel electrophoresis (DGGE) fingerprinting analysis.

RESULTS

Compulsive HD rats showed a lower bacterial diversity than LD rats, irrespectively of the diet. The TRP-depleted HD rats, the only group increasing compulsive licking in SIP, showed a reduction of bacterial evenness and a highly functionally organized community compared with the other groups, indicating that this bacterial community is more fragile to external changes due to the dominance of a low number of species. The chronic TRP depletion by diet effectively reduced peripheral plasma 5-HT levels in both HD and LD rats, while plasma BDNF levels were not altered.

CONCLUSIONS

These results highlight the possible implication of reduced microbial diversity in compulsive behaviour and the involvement of the serotonergic system in modulating the gut brain-axis in compulsive spectrum disorders.

Predictive Value of Subacute Heart Rate Variability for Determining Outcome Following Adolescent Concussion

Objective assessments of concussion recovery are crucial for facilitating effective clinical management. However, predictive tools for determining adolescent concussion outcomes are currently limited. Research suggests that heart rate variability (HRV) represents an indirect and objective marker of central and peripheral nervous system integration. Therefore, it may effectively identify underlying deficits and reliably predict the symptomology following concussion. Thus, the present study sought to evaluate the relationship between HRV and adolescent concussion outcomes. Furthermore, we sought to examine its predictive value for assessing outcomes. Fifty-five concussed adolescents (12–17 years old) recruited from a local sports medicine clinic were assessed during the initial subacute evaluation (within 15 days postinjury) and instructed to follow up for a post-acute evaluation. Self-reported clinical and depressive symptoms, neurobehavioral function, and cognitive performance were collected at each timepoint. Short-term HRV metrics via photoplethysmography were obtained under resting conditions and physiological stress. Regression analyses demonstrated significant associations between HRV metrics, clinical symptoms, neurobehavioral function, and cognitive performance at the subacute evaluation. Importantly, the analyses illustrated that subacute HRV metrics significantly predicted diminished post-acute neurobehavioral function and cognitive performance. These findings indicate that subacute HRV metrics may serve as a viable predictive biomarker for identifying underlying neurological dysfunction following concussion and predict late cognitive outcomes.

Neurobiological basis of chiropractic manipulative treatment of the spine in the care of major depression

Background and aim:

Major depressive disorder is associated with an autonomic nervous system imbalance. All the symptoms of depression (high cortisol, high adrenalin, insomnia, agitation, anxiety) can probably be attributed to over-activation of the sympathetic nervous system. We performed this review in order to highlight the possible links between chiropractic intervention, its potential molecular effects and its possible outcomes on patients with depression.

Methods:

We performed a literature search for all the relevant manuscript regarding the effects of chiropractic and depression on the autonomic nervous system.

Results:

Chiropractic care and spinal manipulation regulate the autonomic nervous system at peripheral level and its projections to the central nervous system. In particular, they may activate the parasympathetic system to counterbalance the activity of the sympathetic system. Vagal parasympathetic stimulation is also considered an effective therapy for major depression as it releases neurotrophins essential for anti-depressive therapies, including brain-derived neurotrophic factor and nerve growth factor.

Conclusion:

Chiropractic and spinal manipulative therapies along with vagal nerve stimulation may therefore be regarded as treatment options for depression. (www.actabiomedica.it)

Decreased Task-Related HRV Is Associated With Inhibitory Dysfunction Through Functional Inter-Region Connectivity of PFC in Major Depressive Disorder

The regulation of the autonomic nervous system (ANS) can improve cognitive function in major depressive disorders (MDD). Heart rate variability (HRV) derives from the dynamic control of the ANS and reflects the balance between the activities of the sympathetic and parasympathetic nervous systems by measuring tiny changes in adjacent heart beats. Task-related HRV may reflect the association between the flexibility of cognition and ANS function. The study was to investigate the neural mechanism of interactions between ANS and cognitive function in MDD with Magnetoencephalography (MEG) measurements. Participants included 20 MDD patients and 18 healthy controls (HCs). All participants were measured with a go/no-go task MEG. HRV indices, the standard deviation of the average normal-to-normal (NN) interval calculated over short periods (SDANN) and the square root of the mean squared differences of successive NN intervals (RMSSD), were derived from the raw MEG data. Results showed that MDD patients showed decreased SDANN and RMSSD. In MDD patients, both resting-state and task-related RMSSD were related to inhibitory and control dysfunction. In the go/no-go task, many areas in the prefrontal cortex (PFC) are responsible for an individual's inhibitory function. A brain MEG functional connectivity analysis revealed that there were significant differences in four brain regions within the prefrontal cortex (PFC) between MDD patients and HCs. Task-related RMSSD in HCs were related to the functional connectivity between the left middle frontal gyrus and the anterior cingulate cortex (ACC), while in MDD patients, these values were not related to the above functional connectivity but were related to the functional connectivity between the left middle frontal gyrus and insula. However, the resting-state RMSSD value was not related to these significant difference functional connectivity networks in all participants. It concludes that the decreased task-related HRV is associated with inhibitory dysfunction through functional inter-region connectivity in the PFC in MDD, and the task-related HRV can be used as an index of the association between MDD and autonomic dysregulation.

Autonomic nervous system development and its impact on neuropsychiatric outcome

The central autonomic nervous system (ANS) is essential for maintaining cardiovascular and respiratory homeostasis in the newborn and has a critical role in supporting higher cortical functions. At birth, the central ANS is maturing and is vulnerable to adverse environmental and physiologic influences. Critical connections are formed early in development between the ANS and limbic system to integrate psychological and body responses. The Polyvagal Theory, developed by Stephen Porges, describes how modulation of the autonomic vagal impulse controls social responses and that a broad range of neuropsychiatric disorders may be due to impaired vagal balance, with either deficient vagal tone or excessive vagal reactivity. Under additional circumstances of prematurity, growth restriction, and environmental stress in the fetus and newborn, the immature ANS may undergo "dysmaturation". Maternal stress and health as well as the intrauterine environment are also quite important and have been implicated in causing ANS changes in the infant and neuropsychiatric diseases in children. This review will cover the aspects of ANS development and maturation that have been associated with neuropsychiatric disorders in children.