Effect of Cold Stress on Neurobehavioral and Physiological Parameters in Rats

Effects of chronic intermittent cold stress on anxiety-depression-like behaviors in adolescent rats

Stress, which triggers numerous physiological and behavioral responses in the organism, is a significant risk factor that contributes to the development of psychiatric disorders such as depression and anxiety. This study aimed to investigate the inflammation, oxidative stress status, anxiety, and depression-like behaviors of adolescent rodents exposed to chronic intermittent cold stress. Adolescent male rats were subjected to a modified chronic intermittent cold stress model (21 days, 1hour/day, 4 °C). Depression-like behaviors were evaluated using the sucrose preference and forced swimming tests, while anxiety-like behaviors were assessed using the open field, elevated plus maze, and light-dark box tests. We measured levels of cortisol, tumor necrosis factor-α, interleukin-1β, brain-derived natriuretic factor, reactive oxygen species, malondialdehyde, total oxidants and antioxidants, and other chemicals in the prefrontal cortex, thalamus, striatum, and hippocampus brain regions of rats using ELISA and colorimetric methods. Data were analyzed using Student's t-test and Pearson correlation analysis. After the cold stress treatment, both anxiety and depression-like behaviors increased remarkably in the subjects. Our study revealed significant changes in various brain regions among the stress-exposed subjects. Cold stress resulted in decreased BDNF levels in the prefrontal cortex and striatum (p < 0.05), increased cortisol levels in the prefrontal cortex (p < 0.05), increased IL-1β levels in the hippocampus and thalamus (p < 0.05), increased protein carbonyl levels in the striatum (p < 0.05), and decreased TAS in the prefrontal cortex and thalamus (p < 0.05). Adolescent rats exposed to cold exhibit both anxiety- and depression-like behaviors. This study observed an increase in inflammation and oxidative stress in various brain regions, yet the responses to stress varied. Our findings suggest that adolescence is a period of heightened sensitivity to stress, which can lead to dramatic consequences.

L-type calcium channel regulation of depression, anxiety and anhedonia-related behavioral phenotypes following chronic stress exposure

Exposure to chronic and unpredictable stressors can precipitate mood-related disorders in humans, particularly in individuals with pre-existing mental health challenges. L-type calcium channels (LTCCs) have been implicated in numerous neuropsychiatric disorders, as LTCC encoding genes have been identified as candidate risk factors for neuropsychiatric illnesses. In these sets of experiments, we sought to examine the ability of LTCC blockade to alter depression, anxiety, and anhedonic-related behavioral responses to chronic unpredictable stress (CUS) exposure in female and male rats. Rats first underwent either 21 days of CUS or no exposure to chronic stressors, serving as home cage controls (HCC). Then rats were examined for anhedonia-related behavior, anxiety and depression-like behavioral responses as measured by the sucrose preference test (SPT), elevated plus maze (EPM), and forced swim test (FST). CUS exposed females and males showed anhedonic and anxiogenic-like behavioral responses on the SPT and EPM, respectively, when compared to HCCs. In female and male rats, systemic administration of the LTCC blocker isradipine (0.4 mg/kg and 1.2 mg/kg, I.P.) attenuated the CUS-induced decrease in sucrose preference and reversed the CUS-induced decrease in open arm time. In the FST, systemic isradipine decreased immobility time across all groups, consistent with an antidepressant-like response. However, there were no significant differences in forced swim test immobility time between HCC and CUS exposed animals. Taken together, these data point to a role of LTCCs in the regulation of mood disorder-related behavioral phenotype responses to chronic stress exposure.

Perivascular adipose tissue remodeling impairs vasoreactivity in thermoneutral-housed rats

Objective

Vascular pathology, characterized by impaired vasoreactivity and mitochondrial respiration, differs between the sexes. Housing rats under thermoneutral (TN) conditions causes vascular dysfunction and perturbed metabolism. We hypothesized that perivascular adipose tissue (PVAT), a vasoregulatory adipose depot with brown adipose tissue (BAT) phenotype, remodels to a white adipose (WAT) phenotype in rats housed at TN, driving diminished vasoreactivity in a sex-dependent manner.

Methods

Male and female Wistar rats were housed at either room temperature (RT) or TN. Endpoints included changes in PVAT morphology, vasoreactivity in vessels with intact PVAT or transferred to PVAT of the oppositely-housed animal, vessel stiffness, vessel mitochondrial respiration and cellular signaling.

Results

Remodeling of PVAT was observed in rats housed at TN; animals in this environment showed PVAT whitening and displayed diminished aortae vasodilation (p<0.05), different between the sexes. Juxtaposing PVAT from RT rats onto aortae from TN rats in females corrected vasodilation (p<0.05); this did not occur in males. In aortae of all animals housed at TN, mitochondrial respiration was significantly diminished in lipid substrate experiments (p<0.05), and there was significantly less expression of peNOS (p<0.001).

Conclusions

These data are consistent with TN-induced remodeling of PVAT, notably associated with sex-specific blunting of vasoreactivity, diminished mitochondrial respiration, and altered cellular signaling.

Protective Effects of Long-Term Escitalopram Administration on Memory and Hippocampal BDNF and BCL-2 Gene Expressions in Rats Exposed to Predictable and Unpredictable Chronic Mild Stress

Stress and escitalopram (an anti-stress medication) can affect brain functions and related gene expression. This study investigated the protective effects of long-term escitalopram administration on memory, as well as on hippocampal BDNF and BCL-2 gene expressions in rats exposed to predictable and unpredictable chronic mild stress (PCMS and UCMS, respectively). Male rats were randomly assigned to different groups: control (Co), sham (Sh), predictable and unpredictable stress (PSt and USt, respectively; 2 h/day for 21 consecutive days), escitalopram (Esc; 10 mg/kg for 21 days), and predictable and unpredictable stress with escitalopram (PSt-Esc and USt-Esc, respectively). The passive avoidance test was used to assess behavioral variables. The expressions of the BDNF and BCL-2 genes were assessed using real-time quantitative PCR. Latency significantly decreased in the PSt and USt groups. Additionally, latency showed significant improvement in the PSt-Esc group compared to the PSt group. The expression of the BDNF gene significantly decreased only in the USt group. BDNF gene expression significantly increased in the PSt-Esc and USt-Esc groups compared to their respective stress-related groups, whereas the expression of the BCL-2 gene did not change significantly in both PSt-Esc and USt-Esc groups. PCMS and UCMS had devastating effects on memory. Escitalopram improved memory only under PCMS conditions. PCMS and UCMS exhibited fundamental differences in hippocampal BDNF and BCL-2 gene expressions. Furthermore, escitalopram increased hippocampal BDNF gene expression in the PCMS and UCMS subjects. Hence, neurogenesis occurred more significantly than anti-apoptosis under both PCMS and UCMS conditions with escitalopram.

Ubiquitinome Analysis Uncovers Alterations in Synaptic Proteins and Glucose Metabolism Enzymes in the Hippocampi of Adolescent Mice Following Cold Exposure

Cold exposure exerts negative effects on hippocampal nerve development in adolescent mice, but the underlying mechanisms are not fully understood. Given that ubiquitination is essential for neurodevelopmental processes, we attempted to investigate the effects of cold exposure on the hippocampus from the perspective of ubiquitination. By conducting a ubiquitinome analysis, we found that cold exposure caused changes in the ubiquitination levels of a variety of synaptic-associated proteins. We validated changes in postsynaptic density-95 (PSD-95) ubiquitination levels by immunoprecipitation, revealing reductions in both the K48 and K63 polyubiquitination levels of PSD-95. Golgi staining further demonstrated that cold exposure decreased the dendritic-spine density in the CA1 and CA3 regions of the hippocampus. Additionally, bioinformatics analysis revealed that differentially ubiquitinated proteins were enriched in the glycolytic, hypoxia-inducible factor-1 (HIF-1), and 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathways. Protein expression analysis confirmed that cold exposure activated the mammalian target of rapamycin (mTOR)/HIF-1α pathway. We also observed suppression of pyruvate kinase M2 (PKM2) protein levels and the pyruvate kinase (PK) activity induced by cold exposure. Regarding oxidative phosphorylation, a dramatic decrease in mitochondrial respiratory-complex I activity was observed, along with reduced gene expression of the key subunits NADH: ubiquinone oxidoreductase core subunit V1 (Ndufv1) and Ndufv2. In summary, cold exposure negatively affects hippocampal neurodevelopment and causes abnormalities in energy homeostasis within the hippocampus.

Cannabinoid and Serotonergic Systems: Unraveling the Pathogenetic Mechanisms of Stress-Induced Analgesia

The perception of "stress" triggers many physiological and behavioral responses, collectively called the stress response. Such a complex process allows for coping with stress and also triggers severe pathology. Because of the multidirectional effect of stress on the body, multiple systems participate in its pathogenesis, with the endogenous cannabinoid and the serotoninergic ones among them. These two systems also take part in the pain perception decrease, known as stress-induced analgesia (SIA), which can then be taken as an indirect indicator of the stress response. The aim of our study was to study the changes in cold SIA (c-SIA) resulting from the exogenous activation of cannabinoid receptor type 1 (CB1) and 5-hydroxytryptamine (5-HT, serotonin) receptor type 1A (5-HT1A). Various combinations of agonists and/or antagonists of CB1 and 5-HT1A, before or after 1 h of cold exposure, were applied, since we presumed that the exogenous activation of the receptors before the cold exposure would influence the pathogenesis of the stress response, while their activation after the stressful trigger would influence the later development. Our results show that the serotonergic system "maintained" c-SIA in the pre-stress treatment, while the cannabinoids' modulative effect was more prominent in the post-stress treatment. Here, we show the interactions of the two systems in the stress response. The interpretation and understanding of the mechanisms of interaction between CB1 and 5-HT1A may provide information for the prevention and control of adverse stress effects, as well as suggest interesting directions for the development of targeted interventions for the control of specific body responses.

Effects and mechanisms of extremely cold environment on body response after trauma

With the outbreak of the Ukrainian crisis, extremely cold environment warfare has once again become the focus of international attention. People exposed to extremely cold environments may suffer from cold damage, further aggravate trauma, trigger high disability and mortality rates, and even cause serious sequelae. To declare the effects and mechanisms of the extremely cold environment on the body after trauma, this paper reviews, firstly, physiological reaction of human body in an extremely cold environment. Then, the post-traumatic body response in an extremely cold environment was introduced, and finally, the sequelae of trauma in extremely cold environment was further summarized in the paper. The results indicated that extremely cold environment can cause a series of damage to the body, especially the body after trauma. The extremely cold factor is a double-edged sword, showing a favorable and unfavorable side in different aspects. Moreover, in addition to the trauma suffered by the body, the subsequent sequelae such as cognitive dysfunction, anxiety, depression and even post-traumatic stress disorder may also be induced. The paper summarizes the human body's physiological response in an extremely cold environment, and declares the effects and mechanisms of the extremely cold environment on the body after trauma, which may provide a theoretical basis for effectively improving the level of combat trauma treatment in extremely cold regions.

The Influence of Topinambur and Inulin Preventive Supplementation on Microbiota, Anxious Behavior, Cognitive Functions and Neurogenesis in Mice Exposed to the Chronic Unpredictable Mild Stress

Daily living and functioning under stress can lead to mental health problems such as anxiety or depression. Over the past decades, a number of studies have been conducted to determine the relationship between the central nervous system (CNS), intestinal flora and bidirectional communication along the gut brain axis (GBA) in the maintaining of homeostasis. One of the most important factors regulating GBA functioning in exposure to stress may be a proper diet enriched in the supplementation with pre-, pro-and synbiotics. In the present study, we examined whether a 10-week oral preventive supplementation with natural prebiotics: topinambur powder (TPB) and chicory root inulin (INU) influenced an anxiety, depressive behavior and cognition in mice exposed to the chronic unpredictable mild stress (CUMS). Additionally, a fluoxetine (FLU) has been used as a reference antidepressive drug. Furthermore, we assessed the effect of TPB, INU and FLU administration on neurogenesis in mice exposed to CUMS and finally analyzed fecal microbiota for possible changes after TPB and INU supplementation in CUMS induced mice. Results obtained from the behavioral studies (elevated plaze maze, forced swim and Morris water maze test) indicated, that 10 week supplementation with TPB (250 mg/kg) and INU (66 mg/kg), similarly to FLU (12 mg/kg), significantly mitigated an anxiety and stress as well as protected learning and memory functions in the CUMS induced mice compared to the control stressed group. Additionally, TPB and INU CUMS mice showed significantly higher level of neurogenesis in comparison to control CUMS group. Interestingly, results obtained from the fecal microbiota analysis showed a beneficial effect of TPB and INU supplementation against CUMS-induced intestinal dysbiosis in mice. In conclusion, the obtained results showed that a long-term, preventive supplementation with TPB or INU alleviates the negative effects such as anxiety, cognitive disorders or dysbiosis in mice exposed to chronic unpredictable stress.

Cold stress during the perinatal period leads to developmental and neurobehavioral toxicity in zebrafish larvae

In nature, cold stress is a core threat to aquatic organisms. But the neurodevelopmental effects of cold stress during the perinatal period on the offspring development were unknown. In the present study, adult zebrafish were cold-stressed at 18 °C for five days before spawning, and then the fertilized eggs were raised at 18, 24, or 28 °C from 0 to 120 h post fertilization (hpf). The resulting embryos and larvae were assessed for developmental and neurobehavioral responses. Our findings showed that embryos raised at 18 °C (Cold+++) suffered hatching failure and death, at 24 °C (Cold++) had decreased hatching, while those raised at 28 °C (Cold+) exhibited no developmental adversity. The neurobehavioral assessment showed that embryos from Cold+ and Cold++ groups displayed decreased motor behaviors, including spontaneous movement at 20-24 hpf, touch response at 48 hpf, and swimming speed at 120 hpf. In addition, cold stress during perinatal stage irreversibly affected larval social behaviors examined during 10-13 days post fertilization (dpf), such as unconsolidated shoaling, increased mirror attacks, and decreased social contacts. Notably, behavioral adversity was more pronounced in larvae from the Cold ++ group than those from the Cold+ group. Mechanistically, cold stress increased cell apoptosis, evidenced by increased acridine orange positive cells at 24 hpf and upregulation of casp8 at 120 hpf, increased oxidative stress (upregulation of cat and nos1) at 120 hpf, delayed motor neuron extension at 72 hpf, and upregulated nrxn2 and rab33a at 120 hpf. Our data indicate that cold stress during the perinatal period impaired neural development in zebrafish larvae, showing high mental health risk. These findings highlight cold stress should be avoided during the perinatal period for both aquatic fish or even humans.

Spexin modulates molecular thermogenic profile of adipose tissue and thermoregulatory behaviors in female C57BL/6 mice

Thermoregulation is the physiological process by which an animal regulates body temperature in response to its environment. It is known that galanin, a neuropeptide widely distributed throughout the central nervous system and secreted by the gut, plays a role in thermoregulatory behaviors and metabolism. We tested the ability of the novel neuropeptide spexin, which shares sequence homology to galanin, to regulate these functions in female mice. Supraphysiological levels of spexin in C57BL/6 mice did not lead to weight loss after 50 days of treatment. Behavioral analysis of long-term spexin treatment showed it decreased anxiety and increased thermoregulatory nest building, which was not observed when mice were housed at thermoneutral temperatures. Treatment also disrupted the thermogenic profile of brown and white adipose tissue, decreasing mRNA expression of Ucp1 in BAT and immunodetection of β3-adrenergic receptors in gWAT. Our results reveal novel functions for spexin as a modulator of thermoregulatory behaviors and adipose tissue metabolism.