Effects of Melatonin on Adrenal Cortical Functions of Indian Goats under Thermal Stress

Effect of heat stress on blood biochemistry and energy metabolite of the Dazu black goats

The objective of this study was to determine the effects of heat stress (HS) on physiological, blood biochemical, and energy metabolism in Dazu black goats. Six wether adult Dazu black goats were subjected to 3 experimental periods: high HS (group H, temperature-humidity index [THI] > 88) for 15 d, moderate HS (group M, THI was 79-88) for 15 d, and no HS (group L, THI < 72) for 15 d. Rectal temperature (RT) and respiratory rate (RR) were determined on d 7 and 15 of each period, and blood samples were collected on d 15 of each period. All goats received glucose (GLU) tolerance test (GTT) and insulin (INS) tolerance test on d 7 and d 10 of each period. The results showed that HS decreased dry matter intake (DMI) and INS concentration (p < 0.05), and increased RT, RR, non-esterified fatty acid (NEFA), cortisol (COR), and total protein (TP) concentrations (p < 0.05). Compared to group L, the urea nitrogen (BUN) concentration increased and GLU concentration decreased in group H (p < 0.05). During the GTT, the area under the curve (AUC) of GLU concentrations increased by 12.26% (p > 0.05) and 40.78% (p < 0.05), and AUC of INS concentrations decreased by 26.04 and 14.41% (p < 0.05) in groups H and M compared to group L, respectively. The INS concentrations were not significant among the three groups (p > 0.05) during the ITT. A total of 60 differentially expressed metabolites were identified in response to groups H and M. In HS, changes in metabolites related to carbohydrate metabolism and glycolysis were identified (p < 0.05). The metabolites related to fatty acid β-oxidation accumulated, glycogenic and ketogenic amino acids were significantly increased, while glycerophospholipid metabolites were decreased in HS (p < 0.05). HS significantly increased 1-methylhistidine, creatinine, betaine, taurine, taurolithocholic acid, inosine, and hypoxanthine, while decreasing vitamin E in blood metabolites (p < 0.05). In summary, HS changed the metabolism of fat, protein, and energy, impaired GLU tolerance, and mainly increased amino acid metabolism to provide energy in Dazu black goats.

Melatonin as an anti-stress signal: effects on an acute stress model and direct actions on interrenal tissue in goldfish

Background

Melatonin is a key hormone in regulation of circadian rhythms, and involved in many rhythmic functions, such as feeding and locomotor activity. Melatonin reportedly counteracts stress responses in many vertebrates, including fish. However, targets for this action of melatonin and underlying mechanisms remain unknown.

Results

This study reports potential anti-stress properties of melatonin in goldfish (Carassius auratus), with a focus on its effect on plasma cortisol, food intake, and locomotor activity, all of them involved in the responses to stress exposure. Indeed, acute injection of melatonin counteracted stress-induced hypercortisolinemia and reduced food intake. The reduced locomotor activity following melatonin treatment suggests a possible sedative role in fish. To assess whether this anti-stress effects of melatonin involve direct actions on interrenal tissue, in vitro cultures of head kidney (containing the interrenal cortisol-producing tissue) were carried out in presence of ACTH, melatonin, and luzindole, an antagonist of melatonin receptors. Melatonin in vitro reduced ACTH-stimulated cortisol release, an effect attenuated by luzindole; this suggests the presence of specific melatonin receptors in interrenal tissue.

Conclusions

Our data support a role for melatonin as an anti-stress signal in goldfish, and suggest that the interrenal tissue of teleosts may be a plausible target for melatonin action decreasing cortisol production.

Physiological, haematological and electroencephalographic responses to heat stress in Katjang and Boer goats

The present study aimed to determine the effect of repeated heat stress on serum levels of cortisol (CORT), acute phase proteins (APP) and heat shock protein (HSP) 70, haematological indicators, and electroencephalographic (EEG) response in the native Katjang and exotic Boer goats. Six female Katjang (15.7 kg ± 0.68) and six female Boer (16.8 kg ± 1.16) goats aged 5 to 6 months old were exposed to 38 ± 1℃ for 8 h, and the procedure was repeated at three different weeks (weeks 1, 2 and 3). Measurements of rectal temperatures and EEG activity and collection of blood samples were conducted before heat exposure (0 h), immediately after the heat exposure (8 h), and 8 h after completion of heat exposure (16 h) (recovery period). The current results revealed that the Boer animals had significantly higher rectal temperatures (RT), haemoglobin (Hb) and packed cell volume (PCV) counts than their Kajang counterparts. There were significant breed × stage of heat treatment (SHT) × week of heat treatment (WHT) interactions for neutrophil to lymphocyte ratios (NLR). In general, the Katjang animals had elevated NLR compared to those of Boer. The Boer goats had reduced capacity to express serum HSP70 compared to their Katjang counterparts following the heat challenge at week 3. Boer goats demonstrated higher delta waves than the Katjang group, which suggested the former were more stressed following the heat exposure. Breed had a negligible effect on CORT, APP, WBC counts and backfat thickness. Our findings suggested that the Katjang breed, as measured by RT, HB and PCV count, and EEG activity, could be more tolerant to heat stress than Boer. The Katjang goats showed higher HSP70 expression than their Boer counterparts, suggesting improved thermoregulation in the former.

Molecular Mechanism of m6A Methylation Modification Genes METTL3 and FTO in Regulating Heat Stress in Sheep

Heat stress is an important environmental factor affecting livestock production worldwide. Primary hepatocytes and preadipocytes derived from Hu sheep were used to establish a heat stress model. Quantitative reverse transcriptase-PCR (qRT-PCR) analysis showed that heat induction significantly increased the expression levels of heat stress protein (HSP) genes and the N6-methyladenosine (m6A) methylation modification genes: methyltransferase-like protein 3 (METTL3), methyltransferase-like protein 14 (METTL14), and fat mass and obesity associated protein (FTO). Heat stress simultaneously promoted cell apoptosis. Transcriptome sequencing identified 3980 upregulated genes and 2420 downregulated genes related to heat stress. A pathway enrichment analysis of these genes revealed significant enrichment in fatty acid biosynthesis, degradation, and the PI3K-Akt and peroxisome proliferator-activated receptor (PPAR) signaling pathways. Overexpression of METTL3 in primary hepatocytes led to significant downregulation of HSP60, HSP70, and HSP110, and significantly increased mRNA m6A methylation; FTO interference generated the opposite results. Primary adipocytes showed similar results. Transcriptome analysis of cells under METTL3 (or FTO) inference and overexpression revealed differentially expressed genes enriched in the mitogen-activated protein kinase (MAPK) signaling pathways, as well as the PI3K-Akt and Ras signaling pathways. We speculate that METTL3 may increase the level of m6A methylation to inhibit fat deposition and/or inhibit the expression of HSP genes to enhance the body's resistance to heat stress, while the FTO gene generated the opposite molecular mechanism. This study provides a scientific basis and theoretical support for sheep feeding and management practices during heat stress.

The Effect of Daytime Ingestion of Melatonin on Thyroid Hormones Responses to Acute Submaximal Exercise in Healthy Active Males: A Pilot Study

It is well known that exercise increases the activity of thyroid glands and raises the blood level of melatonin. The increase of melatonin during exercise may be linked to a rise in thyroid-stimulating hormone (TSH). No previous study has investigated the combined effects of melatonin ingestion and acute submaximal exercise on thyroid hormones’ responses. The purpose of this pilot study was to explore the effects of daytime ingestion of melatonin on thyroid hormones’ responses to acute submaximal exercise. After 50 min of either melatonin (6 mg) or placebo ingestion, eight physical education students (mean ± standard deviation of age: 22 ± 1 years) were asked to run for 45 min at 60% of their maximum aerobic speed. Free thyroxine (fT4) and TSH were measured in plasma samples before and immediately after exercise. After submaximal exercise, TSH increased by 54% in both placebo and melatonin conditions. There was no significant (Condition × Exercise) interaction, and no significant condition effect for TSH. The fT4 remained unchanged before/after submaximal exercise in both placebo [15.2 (1.9) and 15.0 (1.6) pmol/L, respectively, p > .05], and melatonin [16.7 (2.7) and 16.3 (2.7) pmol/L, respectively, p > .05] conditions. There was no significant (Condition × Exercise) interaction, no significant exercise effect, and no significant condition effect for fT4. To conclude, acute melatonin ingestion did not affect thyroid hormones’ responses to submaximal exercise.

Stress associated ovarian dysfunctions in a seasonal breeder Funambulus pennanti: Role of glucocorticoids and possible amelioration by melatonin

Studies have shown that stress caused by lack of physical activity disrupts the normal pattern of glucocorticoid secretion which adversely affects the reproductive axis. We studied the effect of chronic movement restriction on ovarian responses in the Indian Palm Squirrel Funambulus pennanti, a highly active diurnal rodent. Physical restraint of squirrels induced stress that led to a significant increase in plasma cortisol, corticosterone and decreased 17β-estradiol level leading to follicular atresia. Ovarian Reactive Oxygen Species (ROS) content, lipid peroxidation (LPO), activities of superoxide dismutase (SOD) and catalase (CAT) enzymes increased in restrained squirrels. Elevated ROS increased the oxidative load that led to ovarian cell death as evidenced by increased Bax and decreased Bcl2 expression causing further decline in Aromatase and ERα proteins. To elaborate the mechanism(s) involved in stress induced glucocorticoid mediated oxidative damages to the ovary we extended our study by exposing ovaries in vitro to the synthetic glucocorticoid dexamethasone (200 μM). We observed that glucocorticoid receptor (GR) expression was significantly increased in dexamethasone treated ovaries in vitro with a decrease in expression of Nrf2 and HO-1 proteins. Melatonin supplementation (10 nM) along with dexamethasone significantly decreased ovarian ROS production, lipid peroxidation and increased antioxidant enzyme activities by improving the expression of Nrf2 and HO-1, reinstating the cellular redox homeostasis. Therefore, it can be suggested that physical restraint induced glucocorticoid and its receptor activation interfered with the ovarian antioxidant defense mechanism. Melatonin via its receptor MT1 significantly alleviated ovarian damages acting as a cytoprotective agent.

Effect of Light Regiment on Farrowing Performance and Behavior in Sows

Simple Summary

When sows approach birthing in most commercial farms, they are often exposed to continuous light to help farm workers monitor pig health and progress. Being in constant lighting may have a negative effect on sows as mammals often prefer a quiet environment with low stimulation during birthing. In our study, we placed 15 sows in a 12 h light/12 h dark environment, and 15 sows in 24 h light. Sows were watched for ease of farrowing (measured in total time farrowing, birthing interval, and behavior during farrowing). We also measured total piglets born alive and stillborn piglets. Overall, we observed that sows who received darkness gave birth earlier in gestation. Light availability had no effect on total piglets born alive, farrowing behavior, or total length of time giving birth. It was observed that there were more stillborn animals for the sows who received darkness. Overall, it is possible that light availability could have an impact on farrowing behavior and health; however, more factors should be considered in the environment.

Abstract

The purpose of this study was to investigate the effects of light exposure on farrowing performance in sows. Thirty sows were moved to the farrowing unit at d 110 of gestation and assigned a treatment: 12 h light/12 h dark cycle (Dark) or 24 h light (Light). Treatments began upon entry into the farrowing unit. Video was recorded continuously from initiation of the treatments until completion of farrowing. Data collected included duration of farrowing, birthing interval, and behavior during farrowing. Additionally, the number of total born, liveborn, and stillborn piglets was recorded. Gestation length was different between treatments, with a shorter gestation in Dark treatment sows than Light treatment sows (116.4 vs. 117.1 ± 0.2 d, respectively; p = 0.027). The total duration of parturition and number of liveborn did not differ (p = 0.393). Number of stillborn piglets between treatments did differ (p = 0.018). Dark had more stillborns compared to Light treatment sows (1.5 vs. 0.7 ± 0.2 piglets, respectively). Neither the interval between piglets nor farrowing behavior differed between treatments (p > 0.100). The results from this experiment indicate that a sudden change in photoperiod has the potential to impact the gestation length of sows and number of stillborn pigs.

Heat Stress and Goat Welfare: Adaptation and Production Considerations

This review attempted to collate and synthesize information on goat welfare and production constraints during heat stress exposure. Among the farm animals, goats arguably are considered the best-suited animals to survive in tropical climates. Heat stress was found to negatively influence growth, milk and meat production and compromised the immune response, thereby significantly reducing goats' welfare under extensive conditions and transportation. Although considered extremely adapted to tropical climates, their production can be compromised to cope with heat stress. Therefore, information on goat adaptation and production performance during heat exposure could help assess their welfare. Such information would be valuable as the farming communities are often struggling in their efforts to assess animal welfare, especially in tropical regions. Broadly three aspects must be considered to ensure appropriate welfare in goats, and these include (i) housing and environment; (ii) breeding and genetics and (iii) handling and transport. Apart from these, there are a few other negative welfare factors in goat rearing, which differ across the production system being followed. Such negative practices are predominant in extensive systems and include nutritional stress, limited supply of good quality water, climatic extremes, parasitic infestation and lameness, culminating in low production, reproduction and high mortality rates. Broadly two types of methodologies are available to assess welfare in goats in these systems: (i) animal-based measures include behavioral measurements, health and production records and disease symptoms; (ii) resources based and management-based measures include stocking density, manpower, housing conditions and health plans. Goat welfare could be assessed based on several indicators covering behavioral, physical, physiological and productive responses. The important indicators of goat welfare include agonistic behavior, vocalization, skin temperature, body condition score (BCS), hair coat conditions, rectal temperature, respiration rate, heart rate, sweating, reduced growth, reduced milk production and reduced reproductive efficiency. There are also different approaches available by which the welfare of goats could be assessed, such as naturalistic, functional and subjective approaches. Thus, assessing welfare in goats at every production stage is a prerequisite for ensuring appropriate production in this all-important species to guarantee optimum returns to the marginal and subsistence farmers.

Multilevel Interactions of Stress and Circadian System: Implications for Traumatic Stress

The dramatic fluctuations in energy demands by the rhythmic succession of night and day on our planet has prompted a geophysical evolutionary need for biological temporal organization across phylogeny. The intrinsic circadian timing system (CS) represents a highly conserved and sophisticated internal "clock," adjusted to the 24-h rotation period of the earth, enabling a nyctohemeral coordination of numerous physiologic processes, from gene expression to behavior. The human CS is tightly and bidirectionally interconnected to the stress system (SS). Both systems are fundamental for survival and regulate each other's activity in order to prepare the organism for the anticipated cyclic challenges. Thereby, the understanding of the temporal relationship between stressors and stress responses is critical for the comprehension of the molecular basis of physiology and pathogenesis of disease. A critical loss of the harmonious timed order at different organizational levels may affect the fundamental properties of neuroendocrine, immune, and autonomic systems, leading to a breakdown of biobehavioral adaptative mechanisms with increased stress sensitivity and vulnerability. In this review, following an overview of the functional components of the SS and CS, we present their multilevel interactions and discuss how traumatic stress can alter the interplay between the two systems. Circadian dysregulation after traumatic stress exposure may represent a core feature of trauma-related disorders mediating enduring neurobiological correlates of trauma through maladaptive stress regulation. Understanding the mechanisms susceptible to circadian dysregulation and their role in stress-related disorders could provide new insights into disease mechanisms, advancing psychochronobiological treatment possibilities and preventive strategies in stress-exposed populations.

Physiological, biochemical and endocrine responses of goat kids maintained on two different floor types in hot-dry weather conditions

This study investigated physiological, biochemical and endocrine responses along with nutrient intake and growth of goat kids kept on either wooden slatted or soil floor in hot-dry weather conditions. Twenty kids (age 208 ±1.7 days; live weight 26.2±0.6 kg) were divided into two equal groups and allotted to either soil or slatted floor. After 14 days of adaptation, physiological responses, serum metabolites, enzymes and hormones were estimated at weekly intervals for 28 days. All the physiological responses increased from morning to afternoon with increase intemperature-humidity index. Type of flooring did not significantly influence physiological and growth variables. The serum biochemical, enzyme and endocrine responses were similar between both the groups. Due to lack of significant effect of slatted floor on growing kids, the provision of such floor in goat shelter could be appropriate only if it is economically feasible in terms of initial inputs and labour cost in hot-dry tropical environment.

Towards Heat Stress Management in Small Ruminants – A Review

Small ruminants (sheep and goats) play a predominant role in the economy of million people, and have provided meat, milk, skin, wool and fiber for centuries. Animals undergo various kinds of stressors, i.e. physical, nutritional, chemical, psychological and heat stress (HS). Among all, HS is the most concerning at present in the ever-changing climatic scenario. Climate change is the most serious long-term challenge faced by small ruminants’ owners worldwide. HS results in decreased growth, reproduction, production, milk quantity and quality, as well as natural immunity, making animals more vulnerable to diseases, and even death. Thus, HS results in great economic losses, emphasizing the necessity to objectively assess animal welfare. The increasing demand for animal products paralleled by the frequent hot climate is a serious threat for the agriculture sector. The ability of sheep and goats to cope with HS without harming their welfare and productive performance has been often overrated. To date, little attention has been paid to comprehensive detailed data on the adverse effect of HS on sheep and goats. Therefore, this review discusses in detail the sheep and goats’ behavioral, physiological, molecular/cellular, hematological, biochemical and immunological responses under HS conditions. In addition, this review also presents the adverse effects of HS on reproduction and fertility, milk quantity and quality, feed intake, and water consumption of sheep and goats. Finally, this review suggests various methods for HS alleviation. In conclusion, HS impairs productivity and well-being in sheep and goats. The improved understanding of the impact of HS on small ruminants will help in developing management techniques to alleviate HS and highlighting the need for future researches on HS in sheep and goats.

Potential pleiotropic beneficial effects of adjuvant melatonergic treatment in posttraumatic stress disorder

Loss of circadian rhythmicity fundamentally affects the neuroendocrine, immune, and autonomic system, similar to chronic stress and may play a central role in the development of stress-related disorders. Recent articles have focused on the role of sleep and circadian disruption in the pathophysiology of posttraumatic stress disorder (PTSD), suggesting that chronodisruption plays a causal role in PTSD development. Direct and indirect human and animal PTSD research suggests circadian system-linked neuroendocrine, immune, metabolic and autonomic dysregulation, linking circadian misalignment to PTSD pathophysiology. Recent experimental findings also support a specific role of the fundamental synchronizing pineal hormone melatonin in mechanisms of sleep, cognition and memory, metabolism, pain, neuroimmunomodulation, stress endocrinology and physiology, circadian gene expression, oxidative stress and epigenetics, all processes affected in PTSD. In the current paper, we review available literature underpinning a potentially beneficiary role of an add-on melatonergic treatment in PTSD pathophysiology and PTSD-related symptoms. The literature is presented as a narrative review, providing an overview on the most important and clinically relevant publications. We conclude that adjuvant melatonergic treatment could provide a potentially promising treatment strategy in the management of PTSD and especially PTSD-related syndromes and comorbidities. Rigorous preclinical and clinical studies are needed to validate this hypothesis.

Feasibility and validity of animal-based indicators for on-farm welfare assessment of thermal stress in dairy goats

This investigation tested the feasibility and validity of indicators of cold and heat stress in dairy goats for on-farm welfare assessment protocols. The study was performed on two intensive dairy farms in Italy. Two different 3-point scale (0-2) scoring systems were applied to assess cold and heat stress. Cold and heat stress scores were visually assessed from outside the pen in the morning, afternoon and evening in January-February, April-May and July 2013 for a total of nine sessions of observations/farm. Temperature (°C), relative humidity (%) and wind speed (km/h) were recorded and Thermal Heat Index (THI) was calculated. The sessions were allocated to three climatic seasons, depending on THI ranges: cold (<50), neutral (50-65) and hot (>65). Score 2 was rarely assessed; therefore, scores 1 and 2 were aggregated for statistical analysis. The amount of goats suffering from cold stress was significantly higher in the cold season than in neutral (P < 0.01) and hot (P < 0.001) seasons. Signs of heat stress were recorded only in the hot season (P < 0.001). The visual assessment from outside the pen confirms the on-farm feasibility of both indicators: No constraint was found and time required was less than 10 min. Our results show that cold and heat stress scores are valid indicators to detect thermal stress in intensively managed dairy goats. The use of a binary scoring system (presence/absence), merging scores 1 and 2, may be a further refinement to improve the feasibility. This study also allows the prediction of optimal ranges of THI for dairy goat breeds in intensive husbandry systems, setting a comfort zone included into 55 and 70.

Melatonin protects porcine oocyte in vitro maturation from heat stress

Melatonin is a pleiotropic molecule which plays an important role in animal reproductive activities. Because of the increased global warming, the impact of heat stress (HS) on stockbreeding has become an inevitable issue to be solved. To investigate the potential effects of melatonin on the in vitro maturation of porcine oocyte under the HS, a HS model for porcine oocyte maturation has been used in this study and the different concentrations of melatonin (10(-6) -10(-9)  m) were also tested for their protective effects on oocytes. The polar body rate, the index of the nuclear maturation of the oocytes, and the cleavage rate as well as the blastocyst rate were measured to evaluate the developmental competence of the oocytes after parthenogenetic activation (PA). The results showed that HS [in vitro maturation (IVM) 20-24 hr, 42°C] significantly reduced the polar body rate of oocytes and the blastocyte rate of porcine PA embryos, while melatonin (10(-7)  m) application not only improved polar body rate and blastocyte rate, but also preserved the normal levels of steroid hormone which is disrupted by HS. The presence of melatonin (10(-7)  m) during the oocyte maturation under the HS reduced reactive oxygen species (ROS) formation, enhanced glutathione (GSH) production, inhibited cell apoptosis, and increased the gene expressions of SIRT1, AKT2, and Polg2. Importantly, the endogenously occurring melatonin of cumulus-oocyte complexes was significantly induced by HS. The results indicated that melatonin application effectively protected the oocytes from HS. These observations warranted the further studies in vivo regarding to improve the reproductive activities of animals under the global warming environment.

Adaptive capability as indicated by endocrine and biochemical responses of Malpura ewes subjected to combined stresses (thermal and nutritional) in a semi-arid tropical environment

A study was conducted to assess the effect of combined stresses (thermal and nutritional) on endocrine and biochemical responses in Malpura ewes. Twenty eight adult Malpura ewes (average body weight 33.56 kg) were used in the present study. The ewes were divided into four groups viz., GI (n = 7; control), GII (n = 7; thermal stress), GIII (n = 7; nutritional stress) and GIV (n = 7; combined stress). The animals were stall fed with a diet consisting of 60% roughage and 40% concentrate. GI and GII ewes were provided with ad libitum feeding while GIII and GIV ewes were provided with restricted feed (30% intake of GI ewes) to induce nutritional stress. GII and GIV ewes were kept in climatic chamber at 40°C and 55% RH for 6 h a day between 1000 hours and 1600 hours to induce thermal stress. The study was conducted for a period of two estrus cycles. The parameters studied were Hb, PCV, glucose, total protein, total cholesterol, ACP, ALP, cortisol, T(4), T(3), and insulin. Combined stress significantly (P < 0.05) affected all parameters studied. Furthermore, the results revealed that, compared to thermal stress, nutritional stress had a less significant effect on the parameters studied. However, when both these stresses were coupled, they had a severe impact on all the parameters studied in these ewes. It can be concluded from this study that two stressors occurring simultaneously may impact severely on the biological functions necessary to maintain homeostasis in sheep.