Effect of Noise and Music on Neurotransmitters in the Amygdala: The Role Auditory Stimuli Play in Emotion Regulation.

Stress caused by noise is becoming widespread globally. Noise may lead to deafness, endocrine disorders, neurological diseases, and a decline in mental health. The mechanism behind noise-induced neurodevelopmental abnormalities is unclear, but apoptosis and pro-inflammatory signals may play an important role. In this study, weaned piglets were used as a model to explore noise-induced neurodevelopmental abnormalities. We hypothesized that long-term noise exposure would induce anxiety and cause acute stress, exhibited by alterations in neurotransmission in the amygdala. A total of 72 hybrid piglets (Large White × Duroc × Min Pig) were randomly divided into three groups, including noise (exposed to mechanical noise, 80-85 dB), control (blank, exposed to natural background sound, <40 dB), and music (positive control, exposed to Mozart K.448, 60-70 dB) groups. The piglets were exposed to 6 h of auditory noise daily (10:00-16:00) for 28 days. Compared with the control group, piglets exposed to noise showed more aggressive behavior. The expression of Caspase3, Caspase9, Bax, NF-κB (p56), TLR4, MYD88, I κ B α, IL-1 ß, TNF-α, and IL-12RB2 was significantly upregulated in the amygdala, while the expression of Nrf2, HO-1, CAT, and SOD was downregulated in piglets in the noise group. Cell death occurred, and numerous inflammatory cells accumulated in the amygdala of piglets in the noise group. Targeted metabolomics showed that the content of inhibitory neurotransmitter GABA was higher in the amygdala of piglets in the noise group. Compared with the noise group, piglets in the music group displayed more positive emotion-related behaviors. Compared with the noise group, the expression of genes related to apoptosis, inflammation, and oxidative damage was lower in the music group. Cells of the amygdala in the music group were also of normal morphology. Our results show that noise-induced stress causes apoptosis and neuroinflammation in the amygdala and induces anxiety during the early neonatal neural development of piglets. In contrast, to some extent, music alleviates noise-induced anxiety.

Artificial rearing alters intestinal microbiota and induces inflammatory response in piglets.

With the ongoing genetic selection for high prolificacy in sow lines and the improvements in environment and farm management, litter size has increased in recent years. Artificial rearing is becoming widely used to raise the surplus piglets in pig industry. This study aimed to investigate the changes that happened in the morphology, microbiota, mucosal barrier function, and transcriptome caused by artificial rearing in piglet colon. Two hundred and forty newborn piglets were randomly assigned into three treatments, sow rearing until weaning (CON group), artificial rearing from day 21 (AR21 group), and artificial rearing from day 7 (AR7 group). On day 35, the piglets were euthanized to collect colon samples. The results showed that the artificially reared-piglets displayed increased pre-weaning diarrhea incidence and reduced growth performance. Artificial rearing changed the diversity and structure of colonic microbiota and increased relative abundance of harmful bacteria, such as Escherichia-Shigella. In addition, the morphological disruption was observed in AR7 group, which was coincided with decreased tight junction proteins and goblet cell numbers. Moreover, the expression of TNFSF11, TNF-α, IL-1ß, TLR2, TLR4, MyD88, NF-κB, COX-2, PTGEs, iNOS, IL-2, IL-6, IL-17A, and IFN-γ was upregulated in the colon of the artificially reared-piglets, while the expression of IL-1Ra and IκBα was downregulated, indicating that artificial rearing induced inflammatory response through the activation of NF-κB pathway. Furthermore, artificial rearing regulated SLC family members, which affected solute transport and destroyed intestinal homeostasis. In conclusion, artificial rearing caused microbiota alteration, morphology disruption, the destruction of mucosal barrier function, and inflammatory response, and thus, led to subsequent increased diarrhea incidence and reduced growth performance.

Socializing Models During Lactation Alter Colonic Mucosal Gene Expression and Fecal Microbiota of Growing Piglets.

The enrichment of the social environment during lactation alleviates the stress of weaned piglets. It is significant to understand how the enriched social environment improves the weaning stress of piglets. RNA sequencing (RNA-seq) of colonic mucosa, 16S rRNA sequencing of feces, and short-chain fatty acids (SCFAs) of colonic content were used to determine the effects of social contact during lactation. In this study, thirty litter lactating piglets were divided into intermittent social contact (ISC) group that contacted with neighbors intermittently, continuous social contact (CSC) group that contacted with neighbors starting at day (D) 14 after birth, and control (CON) group in which piglets were kept in their original litter. The piglets were weaned at D35 and regrouped at D36. The colonic mucosal RNA-seq, fecal microbes, and SCFAs of colonic contents of 63-day-old piglets were analyzed. The results of RNA-seq showed that compared with the CON group, the pathways of digestion and absorption of minerals, protein, and vitamins of piglets were changed in the ISC group, whereas the pathways of retinol metabolism and nitrogen metabolism in the colonic mucosal were affected and stimulated the immune response in the CSC group. Compared with the CON group, the abundances of pernicious microorganisms (Desulfovibrio, Pseudomonas, Brevundimonas, etc.) in the CSC group and pernicious microorganisms (Desulfovibrio, Neisseria, Sutterella, etc.) and beneficial bacteria (Bifidobacterium, Megamonas, and Prevotella_9) in the ISC group were significantly higher (p < 0.05). The abundances of proinflammatory bacteria (Coriobacteriaceae_unclassified, Coprococcus_3, and Ruminococcus_2) in the CSC group were significantly increased (p < 0.05), but the abundances of SCFAs producing bacteria (Lachnospiraceae_UCG-010, Parabacteroides, Anaerotruncus, etc.) and those of anti-inflammatory bacteria (Eubacterium, Parabacteroides, Ruminiclostridium_9, and Alloprevotella) were significantly reduced (p < 0.05) in the CSC group. Compared with the CON group, the concentrations of microbial metabolites, acetate, and propionate in the colonic contents were reduced (p < 0.05) in the ISC group, whereas the concentration of acetate was reduced (p < 0.05) in the CSC group. Therefore, both ISC and CSC during lactation affected the composition of fecal microbes and changed the expression of intestinal mucosal genes related to nutrient metabolism and absorption of piglets.

Keel bone damage affects behavioral and physiological responses related to stress and fear in two strains of laying hens.

Keel bone damage (KBD) is more prevalent in alternative laying hen housing systems than in conventional cages, and its incidence differs from strain to strain. However, the information of KBD in Lindian chickens, a native Chinese strain, is limited. To investigate the effect of KBD on fearfulness and physiological indicators of stress in Lindian chickens and commercial laying hens, a total of two hundred 25-wk-old chickens (100 Hy-line Brown and 100 Lindian chickens) were studied for 7 wk. The birds were housed in furnished cages with 10 birds per cage for each strain. At 32-wk of age, the birds in each strain were divided into normal (NK), deviated (DK), and fractured (FK) hens according to the keel bone status. Ten birds in each keel bone status per strain were subsequently selected to collect blood for the determination of stress and fear-related indicators, including corticosterone, serotonin, interleukin-1ß, and interleukin-6, and measure fear responses, including novel object test (NOT), human approach test (HAT), and tonic immobility (TI) test. The results showed that egg production was lower and the incidence of keel bone fractures was higher in Lindian chickens than in Hy-line Brown hens (P < 0.05). Lindian chickens showed a significantly increased whole blood serotonin content, NOT-latency, HAT-score, and TI induction times (P < 0.05) and decreased serum interleukin-6 content and TI-duration (P < 0.05) compared with Hy-line Brown hens. Additionally, FK hens had significantly elevated whole blood corticosterone, serum interleukin-1ß and interleukin-6 levels, TI-duration, and NOT-latency (P < 0.05), and a reduced whole blood serotonin content (P < 0.05) compared with NK and DK hens. Our results indicated that KBD affected stress and fear responses, and this impact was mainly reflected by FK hens compared with NK and DK hens. We suggest that keel bone fractures are the main factor impairing hen welfare. Besides, the incidence of keel bone fractures and stress and fear responses of Lindian chickens are more severe than Hy-line Brown laying hens, indicating that the strain type can affect the health and welfare of laying hens.

Keel bone damage (KBD) impairs production performance, welfare, and health in laying hens. This study aimed to compare the incidence of KBD and investigate the effects of KBD on stress and fear in two strains of laying hens. The results showed that commercial Hy-line Brown laying hens had high egg production and low incidence of KBD compared with Lindian chickens, a Chinese native breed. Besides, Lindian chickens had higher blood serotonin content and fear responses to human approach test and novel object test than Hy-line Brown laying hens. In addition, laying hens with keel bone fractures had elevated concentrations of blood corticosterone, interleukin-1ß, and interleukin-6, and had a longer duration of tonic immobility and latency to approach a novel object, as well as reduced blood serotonin content compared with laying hens with normal and deviated keel bone. Overall, keel bone fractures caused stress and fear responses, impairing hen welfare; and behavioral and physiological responses in relation to stress and fear differed between strains of hens.

Stereotypic behaviors are associated with physiology and immunity differences in long-term confined sows.

Pregnant sows in the confined environment have poor welfare and frequently perform stereotypic behaviors. In order to clarify whether highly stereotypic behavior is a sign of increased stress and successfully contributes to coping with or adaptation to adverse environment, fifty pregnant sows (Large White × Landrace) housed in stalls were selected to observe behaviors and analyze physiological parameters [cortisol, major acute phase protein (Pig-MAP) and C-reactive protein (CRP)], and immunological parameters [immunoglobin A (IgA), immunoglobin G (IgG), interleukin 6 (IL-6), interleukin 10 (IL-10), tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ)] in early, middle and late gestation (27th, 62nd and 91st day). A repeated-measures analysis and Friedman test was performed to analyze the differences of behaviors and physiological and immunological parameters. The results showed that lateral lying behavior increased significantly with the progress of sows' gestation, while standing and ventral lying behaviors significantly decreased (p < 0.05). Sham-chewing, bar-biting, trough-biting and rooting behaviors significantly reduced (p < 0.05). Furthermore, there was no significant difference in physiological and immune levels in different gestational periods (p > 0.05). The results also indicated that sham-chewing behavior was positively correlated with serum cortisol, IL-6, IL-10, and negatively correlated with serum IFN-γ in each gestational period (p < 0.05). Trough-biting behavior was positively correlated with serum TNF-α in middle and late gestation (p < 0.05). Rooting behavior was positively correlated with serum IgG in each gestational period, and positively correlated with serum Pig-MAP, IL-6, and IL-10 in middle and late gestation (p < 0.05). In conclusion, the sows with a high incidence of stereotypic behaviors tried to improve stress and humoral immunity to cope with the confined environment, and long-term confined sows might be in a chronic stress state.

Transcriptome Revealed Exposure to the Environmental Ammonia Induced Oxidative Stress and Inflammatory Injury in Spleen of Fattening Pigs.

Ammonia is one of the major environmental pollutants that seriously threaten human health. Although many studies have shown that ammonia causes oxidative stress and inflammation in spleen tissue, the mechanism of action is still unclear. In this study, the ammonia poisoning model of fattening pigs was successfully established. We examined the morphological changes and antioxidant functions of fattening pig spleen after 30-day exposure to ammonia. Effects of ammonia in the fattening pig spleen were analyzed from the perspective of oxidative stress, inflammation, and histone methylation via transcriptome sequencing technology (RNA-seq) and real-time quantitative PCR validation (qRT-PCR). We obtained 340 differential expression genes (DEGs) by RNA-seq. Compared with the control group, 244 genes were significantly upregulated, and 96 genes were significantly downregulated in the ammonia gas group. Some genes in Gene Ontology (GO) terms were verified and showed significant differences by qRT-PCR. The KEGG pathway revealed significant changes in the MAPK signaling pathway, which is strongly associated with inflammatory injury. To sum up, the results indicated that ammonia induces oxidative stress in pig spleen, activates the MAPK signaling pathway, and causes spleen necrosis and injury. In addition, some differential genes encoding epigenetic factors were found, which may be involved in the response mechanism of spleen tissue oxidative damage. The present study provides a transcriptome database of ammonia-induced spleen poisoning, providing a reference for risk assessment and comparative medicine of ammonia.

Abnormal Bone Metabolism May Be a Primary Causative Factor of Keel Bone Fractures in Laying Hens.

Keel bone damage negatively affects the welfare, production performance, egg quality, and mobility of laying hens. This study aimed to investigate whether abnormal bone metabolism causes keel bone damage in laying hens. Eighty Hy-line Brown laying hens were housed in eight furnished cages with 10 birds per cage and studied from 18 to 29 weeks of age (WOA). Accordingly, keel bone status was assessed at 18, 22, 25, and 29 WOA using the X-ray method, and the serum samples of laying hens with normal keel (NK), deviated keel (DK), and fractured keel (FK) that occurred at 29 WOA were collected across all the time-points. Subsequently, the serum samples were used to measure markers related to the metabolism of Ca and P and activities of osteoblast and osteoclast. The results showed that FK laying hens had lighter bodyweight than NK and DK birds throughout the trial (p < 0.05), while the keel bone length and weight were not different in NK, DK, and FK hens at 29 WOA (p > 0.05). Moreover, bone hematoxylin and eosin (H&E) staining and tartrate-resistant acid phosphatase (TRAP) staining indicated that damaged keel bone had evident pathological changes. In the FK hens, serum P level was reduced but serum 1,25-dihydroxy-vitamin D3 (1,25-(OH)2D3) and 25-hydroxyvitamin D3 (25-OHD3) levels were elevated compared to NK hens (p < 0.05). Additionally, DK hens had higher levels of serum 1,25-(OH)2D3, parathyroid hormone (PTH) and calcitonin (CT), and lower level of serum 25-OHD3 than the NK birds (p < 0.05). Furthermore, serum alkaline phosphatase (ALP), osteocalcin (OC), osteoprotegerin (OPG), TRAP, and corticosterone (CORT) levels were elevated in DK and FK hens compared to NK hens (p < 0.05). The levels of serum Ca, P, PTH, ALP, TRAP, OPG, OC, and CORT in laying hens fluctuated with the age of the birds. Generally, the results of this study indicate that keel bone damage, especially fractures, could be associated with abnormal bone metabolism in laying hens.