A terrified-sound stress induced proteomic changes in adult male rat hippocampus

A terrified-sound stress causes cognitive impairment in female mice by impairing neuronal plasticity

Stress is an important environmental factor affecting mental health that cannot be ignored. Moreover, due to the great physiological differences between males and females, the effects of stress may vary by sex. Previous studies have shown that terrified-sound stress, meaning exposed mice to the recorded vocalizations in response to the electric shock by their kind to induce psychological stress, can cause cognitive impairment in male. In the study, we investigated the effects of the terrified-sound stress on adult female mice.

METHODS

32 adults female C57BL/6 mice were randomly divided into control (n = 16) and stress group (n = 16). Sucrose preference test (SPT)was carried out to evaluate the depressive-like behavior. Using Open field test (OFT) to evaluate locomotor and exploratory alterations in mice. Spatial learning and memory ability were measured in Morris Water maze test (MWM), Golgi staining and western blotting showed dendritic remodeling after stress. In addition, serum hormone quantifications were performed by ELISA.

RESULTS

we found the sucrose preference of stress group was significantly decreased (p < 0.05) compared with control group; the escape latency of the stress group was significantly prolonged (p < 0.05), the total swimming distance and the number of target crossings(p < 0.05) were significantly increased (p < 0.05) in MWM; Endocrine hormone, Testosterone (T) (p < 0.05), GnRH (p < 0.05), FSH and LH levels was decreased; Golgi staining and western blotting showed a significant decrease in dendritic arborization, spine density and synaptic plasticity related proteins PSD95 and BDNF in the stress group.

CONCLUSION

Terrified-sound stress induced depressive-like behaviors, locomotor and exploratory alterations. And impaired cognitive by altering dendritic remodeling and the expression of synaptic plasticity-related proteins. However, females are resilient to terrified-sound stress from a hormonal point of view.

In vitro methods in autophagy research: Applications in neurodegenerative diseases and mood disorders

Background

Autophagy is a conserved physiological intracellular mechanism responsible for the degradation and recycling of cytoplasmic constituents (e.g., damaged organelles, and protein aggregates) to maintain cell homeostasis. Aberrant autophagy has been observed in neurodegenerative diseases, including Alzheimer's Disease (AD), Parkinson's Disease (PD), Amyotrophic Lateral Sclerosis (ALS), and Huntington's Disease (HD), and recently aberrant autophagy has been associated with mood disorders, such as depression. Several in vitro methods have been developed to study the complex and tightly regulated mechanisms of autophagy. In vitro methods applied to autophagy research are used to identify molecular key players involved in dysfunctional autophagy and to screen autophagy regulators with therapeutic applications in neurological diseases and mood disorders. Therefore, the aims of this narrative review are (1) to compile information on the cell-based methods used in autophagy research, (2) to discuss their application, and (3) to create a catalog of traditional and novel in vitro methods applied in neurodegenerative diseases and depression.

Methods

Pubmed and Google Scholar were used to retrieve relevant in vitro studies on autophagy mechanisms in neurological diseases and depression using a combination of search terms per mechanism and disease (e.g., "macroautophagy" and "Alzheimer's disease"). A total of 37 studies were included (14 in PD, 8 in AD, 5 in ALS, 5 in %, and 5 in depression).

Results

A repertoire of traditional and novel approaches and techniques was compiled and discussed. The methods used in autophagy research focused on the mechanisms of macroautophagy, microautophagy, and chaperone-mediated autophagy. The in vitro tools presented in this review can be applied to explore pathophysiological mechanisms at a molecular level and to screen for potential therapeutic agents and their mechanism of action, which can be of great importance to understanding disease biology and potential therapeutic options in the context of neurodegenerative disorders and depression.

Conclusion

This is the first review to compile, discuss, and provide a catalog of traditional and novel in vitro models applied to neurodegenerative disorders and depression.

The hearing hippocampus

The hippocampus has a well-established role in spatial and episodic memory but a broader function has been proposed including aspects of perception and relational processing. Neural bases of sound analysis have been described in the pathway to auditory cortex, but wider networks supporting auditory cognition are still being established. We review what is known about the role of the hippocampus in processing auditory information, and how the hippocampus itself is shaped by sound. In examining imaging, recording, and lesion studies in species from rodents to humans, we uncover a hierarchy of hippocampal responses to sound including during passive exposure, active listening, and the learning of associations between sounds and other stimuli. We describe how the hippocampus' connectivity and computational architecture allow it to track and manipulate auditory information - whether in the form of speech, music, or environmental, emotional, or phantom sounds. Functional and structural correlates of auditory experience are also identified. The extent of auditory-hippocampal interactions is consistent with the view that the hippocampus makes broad contributions to perception and cognition, beyond spatial and episodic memory. More deeply understanding these interactions may unlock applications including entraining hippocampal rhythms to support cognition, and intervening in links between hearing loss and dementia.

A terrifying sound stress inhibits hippocampal neurogenesis in the adult male mice

Stress impairs hippocampal neurogenesis. The traditional animal model of stress contains a mixture of physical and psychological stress factors. This leads to difficulty in the evaluation of the effect of pure psychological stress on neurogenesis. In this study, we investigated the effect of pure psychological stress on hippocampal neurogenesis. The pure psychological stress model and the mixed stress model were carried out by terrifying sound and restraint, respectively. The open field test showed that restraint treatment improved the general locomotor activity levels, while terrifying sound treatment had opposite effects. Compared with a normal condition, both terrifying sound stimulation and restraint treatment significantly decreased the number of BrdU and Ki-67 and reduced the positive rate of SOX2/GFAP in the hippocampus. These phenomena indicated that pure psychological stress could decrease the number of neural stem cells and inhibit cell proliferation in the hippocampus of a mouse. Furthermore, compared with the restraint treatment, the neurotransmitters including norepinephrine (NE), 5-hydroxytryptamine (5-HT), and gamma-aminobutyric acid (GABA) had not been affected drastically by terrifying sound stimulation. Our results suggest that the terrifying sound stimulation can be considered as a novel and effective pure psychological stress animal model for the further research on the hippocampus.

β-Endorphin Induction by Psychological Stress Promotes Leydig Cell Apoptosis through p38 MAPK Pathway in Male Rats

Psychological stress (PS) disturbs the reproductive endocrine system and promotes male infertility, but the underlying pathogenic mechanisms have not been extensively studied. This study aimed to uncover the mechanisms of PS-induced male reproductive related abnormalities subjected to a ‘terrified sound’ exposure. Male rats subjected to PS displayed slow growth, decreased sperm quality, abnormal levels of the reproductive endocrine hormones, decreased expression of the reproductive-related proteins androgen-binding protein (ABP) and bromodomain-containing protein (BRDT), increased apoptosis in the testis, and accompanied by elevated levels of β-endorphin (β-EP). These effects were reversed by naloxone. Furthermore, PS-induced β-EP could promote mu opioid receptor (MOR) activation and ensure intracellular p38 MAPK phosphorylation and then lead to Leydig cells (LCs) apoptosis. The current result showed that β-EP was a key factor to PS-induced male infertility.

Effects of a Terrified-Sound Stress on Serum Proteomic Profiling in Mice

The serum proteomic profiles of mice exposed to terrified-sound-induced stress and after stress release were investigated. Serum samples from 32 mice were divided into four groups (n = 8 each) and analyzed using matrix-assisted laser desorption and ionization time-of-flight mass spectrometry techniques (MALDI-TOF MS) combined with magnetic bead-based weak cation-exchange chromatography. ClinProTools software identified several distinct markers that differed between the stressed and control groups and between the stress released and stressed released controls. Of 33 m/z peaks that differed among the four groups, 17 were significantly different (P < 0.05). Five peaks (m/z: 2793.37, 2924.86, 1979.90, 3492.49, 3880.24) showed significant differences in expression after exposure to terrified-sound stress and returned to control levels after stress release. These were sequence identified as peptide regions of dimethylaniline monooxygenase, myosin-9, uncharacterized protein in Rattus norvegicus, apolipoprotein C-I, and plasma serine protease inhibitor (Serpina 5). Our study provides the first evidence of significant changes in serum proteomic profiles in mice exposed to terrified-sound stress, which suggests that protein expression profiles are affected by the stress. Normal expression levels were restored after stress release, suggesting the activation of self-adjustment mechanisms for the recovery of protein expression levels altered by this stress.