The use of carbon dioxide (CO2) exposure as a means of animal euthanasia has received considerable attention in mammals and birds but remains virtually untested in reptiles. We measured the behavioral responses of four squamate reptile species (Homalopsis buccata, Malayopython reticulatus, Python bivitattus, and Varanus salvator) to exposure to 99.5% CO2 for durations of 15, 30, or 90 minutes. We also examined alterations in plasma corticosterone levels of M. reticulatus and V. salvator before and after 15 minutes of CO2 exposure relative to control individuals. The four reptile taxa showed consistent behavioral responses to CO2 exposure characterized by gaping and minor movements. The time taken to lose responsiveness to stimuli and cessation of movements varied between 240-4260 seconds (4-71 minutes), with considerable intra- and inter-specific variation. Duration of CO2 exposure influenced the likelihood of recovery, which also varied among species (e.g., from 0-100% recovery after 30-min exposure). Plasma corticosterone concentrations increased after CO2 exposure in both V. salvator (18%) and M. reticulatus (14%), but only significantly in the former species. Based on our results, CO2 appears to be a mild stressor for reptiles, but the relatively minor responses to CO2 suggest it may not cause considerable distress or pain. However, our results are preliminary, and further testing is required to understand optimal CO2 delivery mechanisms and interspecific responses to CO2 exposure before endorsing this method for reptile euthanasia.
Feed deprivation in poultry farming imposes some degree of stress to the birds, and adversely affects their well -being. Serum levels of acute phase proteins (APP) are potential physiological indicators of stress attributed to feed deprivation. However, it has not been determined how long it takes for a measurable APP response to stressors to occur in avian species. An experiment was designed to delineate the APP and circulating levels of corticosterone responses in commercial broiler chickens to feed deprivation for 30 h. It was hypothesized that feed deprivation would elicit both APP and corticosterone (CORT) reactions within 30 h that is probably associated with stress of hunger. Twenty-one day old birds were subjected to one of 5 feed deprivation periods: 0 (ad libitum, AL), 6, 12, 18, 24, and 30 h. Upon completion of the deprivation period, blood samples were collected to determine serum CORT, ovotransferrin (OVT), α1-acid glycoprotein (AGP), and ceruloplasmin (CP) concentrations. Results showed that feed deprivation for 24 h or more caused a marked elevation in CORT (P=0.002 and P<0.0001, respectively) when compared to AL. However, increases in AGP (P=0.0005), CP (P=0.0002), and OVT (P=0.0003) were only noted following 30 h of feed deprivation. It is concluded that elicitation of AGP, CP, and OVT response may represent a more chronic stressful condition than CORT response in assessing the well-being of broiler chickens.
An experiment was conducted to determine the effect of different stocking densities on serum corticosterone (CORT), ovotransferrin (OVT), α1-acid glycoprotein (AGP) and ceruloplasmin (CP) concentrations, brain heat shock protein (HSP) 70 expression and performance in broiler chickens exposed to unheated and heated conditions. Day-old chicks were stocked at 0.100 m(2)/bird (low density (LD)) or 0.063 m(2)/bird (high density (HD)), in battery cages and housed in environmentally controlled rooms. From 21 to 35 days of age, birds from each stocking density group were exposed to either 24 or 32 °C. Growth performance was recorded during the heat treatment period, and blood and brain samples were collected to determine CORT, OVT, AGP, CP and HSP 70 levels on day 35. Heat treatment but not stocking density was detrimental to growth performance. There were significant temperature × density interactions for CORT, CP and OVT on day 35. Although HD elevated CORT, CP and OVT when compared to LD, the effects of the former were more obvious under heated condition. Both temperature and density had significant effect on AGP and HSP 70. In conclusion, irrespective of temperature, high stocking density was physiologically stressful to broiler chickens, as indicated by CORT, AGP, CP, OVT and HSP 70, but not detrimental to growth performance and survivability. As it was shown in the present study, AGP, CP and OVT could be useful biomarkers to determine the effect of overcrowding and high temperature on the welfare of broiler chickens.
Two hundred thirty-five 1-d-old broiler chickens showing short or long tonic immobility responses were classified as low fear (LF) or high fear (HF) responders, respectively. On d 41, they were subjected to either crating or heat challenge (34 +/- 1 degrees C) for 3 h and its effect on plasma corticosterone concentration, heterophil/lymphocyte ratios, and heat shock protein (HSP) 70 expression in brain tissue were determined. Crating and heat exposure elevated heterophil/lymphocyte ratios in both LF and HF birds. Circulating corticosterone, however, was greater in HF than LF birds after crating and heat challenge. Although differences between fear responder group for HSP 70 were negligible before heat challenge, after 3 h of heat exposure, the response was greater for the HF than the LF group. Both LF and HF showed similar increases in HSP 70 after crating.
Normal rats, on being repetitively stressed by being restrained in a tight container for two hours, had higher levels of plasma corticosterone compared to pre stress values. These rats also reacted to the stress by a behavioral response in which there was marked decrease in locomotor activity assessed by the open field test (pre stress: 71.3 +/- 2.6 squares crossed versus post stress: 14.3 +/- 2.5 squares crossed) by counting the number of squares entered by the rat over 5 minutes. By the 6th to 7th exposures to the repetitive stress, the rats adapted to the stress and had normal plasma corticosterone levels and locomotor activity scores comparable to the pre stress values. These responses to stress were completely blocked by the administration of 0.32 microg/100 g BW of naloxone i.p at 10 minutes prior to the stress. In rats fed with rat chow supplemented with 90 mg/kg rat chow or 150 mg/kg rat chow of vitamin E, there was significant reduction of the plasma corticosterone levels and improvement in the locomotor activity. Stress thus caused opioid mediated increase in plasma corticosterone and reduction in locomotor activity which could be blocked by naloxone. These stress responses probably also involved generation of oxygen free radicals which were scavenged by the vitamin E, thus reducing the effects of repetitive stress on locomotor activity and serum corticosterone levels.
Physiological responses to social isolation stress were compared in 56-day-old male Japanese quail. Birds were fed pretreated diets for 3 days as follows: (i) Basal diet (control); (ii) Basal diet+1500 mg/kg metyrapone (BM); (iii) Basal diet+30 mg/kg corticosterone (BCO); (iv) Basal diet+250 mg/kg ascorbic acid (BC); (v) Basal diet+250 mg/kg α-tocopherol (BE); (vi) Basal diet+250 mg/kg ascorbic acid and 250 mg/kg α-tocopherol (BCE). The birds were subsequently socially isolated in individual opaque brown paper box for 2 hours. Plasma corticosterone (CORT) concentration and heart and brain heat shock protein 70 (Hsp 70) expressions were determined before stress and immediately after stress. Two hours of isolation stress elevated CORT concentration significantly in the control and BE birds but not in the BC, BCE and BM birds. There was a significant reduction in CORT concentration after isolation stress in the BCO group. Isolation stress increased Hsp 70 expression in the brain and heart of control and BM birds. However, brain and heart Hsp 70 expressions were not significantly altered in the isolated BC, BCE and BE birds. Although, the CORT concentration of BM birds was not affected by isolation stress, Hsp70 expression in both brain and heart were significantly increased. Moreover, exogenous corticosterone supplementation did not result in elevation of Hsp 70 expression. It can be concluded that, although Hsp 70 induction had not been directly affected by CORT concentration, it may be modulated by the HPA axis function via activation of ACTH.
This study aims to compare the effects of social instability stress on memory and anxiety- and depressive-like behaviour between sham-operated controls and ovariectomised (OVX) rats. Forty adult female Sprague-Dawley rats (8 weeks old) were randomly divided into four groups, (n = 10 per group). These were non-stressed sham-operated control rats, stressed sham-operated control rats, non-stressed OVX rats, and stressed OVX rats. The rats were subjected to social instability stress procedure for 15 days. Novel object recognition, open field, and forced swim tests were conducted after the stress procedure. Serum estradiol, ACTH and corticosterone levels were measured using commercially available ELISA kits. Lower serum estradiol level and uterine weight with higher weight gain were observed in OVX rats compared to sham-operated controls. Serum ACTH, and corticosterone levels were higher in stressed compared to non-stressed groups. Memory deficit and anxiety- and depressive-like behaviour were significantly increased in stressed compared to non-stressed OVX rats but these changes were not seen in sham-operated controls. These results suggest that the high circulating corticosterone acts synergistically with low circulating estradiol to exert negative effects on mood and memory function.
Domestic animals have been modified by selecting individuals exhibiting desirable traits and culling the others. To investigate the alterations introduced by domestication and selective breeding in heat stress response, 2 experiments were conducted using Red Jungle Fowl (RJF), village fowl (VF), and commercial broilers (CB). In experiment 1, RJF, VF, and CB of a common chronological age (30 d old) were exposed to 36 ± 1°C for 3 h. In experiment 2, RJF, VF, and CB of common BW (930 ± 15 g) were subjected to similar procedures as in experiment 1. Heat treatment significantly increased body temperature, heterophil:lymphocyte ratio, and plasma corticosterone concentration in CB but not in VF and RJF. In both experiments and irrespective of stage of heat treatment, RJF showed lower heterophil:lymphocyte ratio, higher plasma corticosterone concentration, and higher heat shock protein 70 expression than VF and CB. It can be concluded that selective breeding for phenotypic traits in the domestication process has resulted in alterations in the physiology of CB and concomitantly the ability to withstand high ambient temperature compared with RJF and VF. In other words, domestication and selective breeding are leading to individuals that are more susceptible to stress rather than resistant. It is also apparent that genetic differences in body size and age per se may not determine breed or strain variations in response to heat stress.
An experiment was conducted to determine the effects of 2 types of housing systems and early age feed restriction on heat shock protein (hsp) 70 expression and blood parameters in broiler chickens subjected to road transportation. On d 1, female chicks were housed either in windowless environmentally controlled chambers (temperature was set at 32 degrees C on d 1 and gradually reduced to 23 degrees C by d 21; CH) or in conventional open-sided houses (OH) with cyclic temperatures (minimum, 24 degrees C; maximum, 34 degrees C). Equal number of chicks from each housing system were subjected to either ad libitum feeding or 60% feed restriction on d 4, 5, and 6 (FR). On d 42, all of the birds were crated and transported for 6 h. Birds raised in OH had smaller increases in heterophil:lymphocyte ratios and plasma corticosterone concentrations than those of CH. Subjecting birds to FR dampened heterophil:lymphocyte ratios and corticosterone reactions to transportation. After 4 h of transportation, the OH birds had greater hsp 70 expression than their CH counterparts. Within the CH, the FR chicks showed higher hsp 70 density than those of the ad libitum-fed group. Except for glucose, housing system had a negligible effect on serum levels of cholesterol, potassium, and chloride. Collectively, the results suggest that the improved tolerance to transport stress in OH and FR chicks could be associated with better hsp 70 expression.
An experiment was conducted to determine the effects of combining both pleasant and unpleasant contacts with human beings on physiology and behavior of broiler chickens. Birds were subjected to the following treatments: (i) received no physical or visual contact with humans (control); (ii) from d 1 to 28, chicks were individually stroked gently for 30 s once daily (PL); (iii) from d 1 to 28, chicks were picked up individually, suspended by both legs, exposed to recorded noise, and swung gently for 15 s once daily (UNPL); (iv) from d 1 to 14 and from d 15 to 28, chicks were subjected to PL and UNPL, respectively (PL-UNPL); and (v) from d 1 to 14 and from d 15 to 28, chicks were subjected to UNPL and PL, respectively (UNPL-PL). On d 42, birds from each treatment group were road-transported for 3 h. Heat shock protein (hsp) 70 expression, plasma levels of corticosterone, serum creatine kinase concentration, heterophil/lymphocyte ratios (HLR), and tonic immobility duration were determined pre- and posttransit. There were significant (P < 0.05) duration of transportation × human contact treatment interactions for HLR and hsp 70 density. Following transit, the PL chicks had significantly (P < 0.05) lower HLR and greater hsp 70 density than the other groups. The corticosterone of PL and UNPL chicks were lower than their control, PL-UNPL, and UNPL-PL counterparts. The PL and PL-UNPL treatments were effective in shortening tonic immobility duration significantly (P < 0.05). Except for UNPL-PL, the serum creatine kinase activity of PL was significantly lower than the other groups. In conclusion, subjecting birds to pleasant human contact reduced stress and fear reactions to transportation by enhancing the ability to express hsp 70 in the brain. Unpleasant human contact had adverse effect on the birds' response to transportation. Early age pleasant experience with humans failed to negate the adverse effects of subsequent unpleasant contact.
This study tested the possibility of adrenal autotransplantation in rats. Since the cortex and the medulla of the adrenal gland were from different origin embryologically, either whole adrenal glands (ADR), or capsule and cortex (CAP) or medulla (MED) were autotransplanted in the subcutaneous tissue. The functions of regenerated adrenal nodules were tested by measuring plasma corticosterone levels every fortnight. At the end of 9 weeks the rats were exposed to hypovolemic shock followed by naloxone injection to reverse the shock response. Results showed that rats transplanted with either cortex or whole adrenal started secreting corticosterone at 5 weeks post-transplantation (107.73 +/- 21.98 ng/ml, 126.04 +/- 48.41 ng/ml, respectively). Corticosterone levels increased to the value which were not significantly different from control by 9 weeks post-transplantation. However, rats transplanted with adrenal medulla showed very low corticosterone levels. Nine weeks post-transplantation, the mean blood pressure (MBP) of the CAP group was 135 +/- 13 mmHg and was not significantly different from sham-operated controls, whereas MBP of MED group was significantly lower than sham-operated animals (99 +/- 11 mmHg versus 141 +/- 9 mmHg). The MBP of the ADR group was also lower compared to sham-operated controls (112 +/- 17 mmHg P < 0.05). The MBP of the adrenal group was not statistically significant compared to the CAP group. After 1% body weight haemorrhage, the MBP decreased significantly in ADR (45 +/- 5 mmHg, P < 0.05) and MED group (36 +/- 9 mmHg, P < 0.001) compared to sham-operated rats (78 +/- 11 mmHg) but not in the CAP (56 +/- 9 mmHg). It was concluded that autotransplanted whole adrenal or adrenocortical tissues survived subcutaneously and produced sufficient corticosterone to alleviate haemorrhagic shock. Adrenal medullary tissue failed to regenerate subcutaneously and the presence of adrenal medullary tissue may suppressed the growth of transplanted adrenal gland.
1. This study was carried out to determine the effect of short-term and long-term ingestion of glycyrrhizic acid on the response to 2 h of restraint stress by measuring locomotor activity and plasma corticosterone levels. 2. Male Sprague-Dawley rats were randomly assigned into four groups, each group having eight rats. Group 1 (control) was given ordinary tap water, while groups 2 (short term), 3 and 4 (both long term) were given tap water containing 1 mg/mL glycyrrhizic acid to drink for 10 days, 4 weeks and 9 weeks, respectively. All the rats were subjected to 2 h of restraint stress and the locomotor activity assessed using an activity test in an open field arena followed by blood sampling to determine the plasma corticosterone level. These procedures were repeated daily for 14 days. 3. The basal locomotor activity scores for rats given glycyrrhizic acid for 10 days or 4 weeks were similar to those of controls; however, that of the rats treated long term with glycyrrhizic acid was significantly lower (21.0 +/- 3.0 squares crossed; P < 0.0005). Following the first period of restraint stress there was a highly significant decrease in locomotor activity, which remained significantly lower until the seventh and subsequent periods, indicating an adaptation to the repeated stress had occurred. Although the decrease in locomotor activity was partially blocked and adaptation to repetitive stress was enhanced in the rats given glycyrrhizic acid for 10 days, this was not seen in rats treated with glycyrrhizic acid for 4 or 9 weeks. The corticosterone levels in control rats were significantly elevated for 4-5 days following the exposure to repetitive stress but decreased gradually from day 7 onwards. However, both short- and long-term glycyrrhizic acid-treated rats had higher plasma corticosterone levels than the controls (P < 0.05). 4. In conclusion, repetitive restraint stress caused decreased locomotor activity associated with increased plasma corticosterone levels, both of which, in normal rats, decreased with adaptation to stress. The stress response was partially blocked and adaptation enhanced in rats given glycyrrhizic acid for 10 days, but not in rats given glycyrrhizic acid for 4 and 9 weeks. Glycyrrhizic acid ingestion caused high plasma corticosterone.
The use of nanominerals, such as nano-zinc, represents a promising and emerging technology in the animal farming industry. Due to the small particle size and bioavailability of nano-zinc, it can be easily assimilated in the digestive system, thereby reducing excretion and environmental pollution. The present study was conducted to assess the effects of zinc oxide nanoparticles (ZnONPs) on the growth performance, zinc (Zn) concentration in edible tissues, thiobarbituric acid reactive substance, and corticosterone concentrations in broilers reared under normal or heat stress environmental conditions. The experiment was performed with a completely randomized design based on a 4 × 2 factorial arrangement consisting of 4 diets (basal diet + 60 mg/kg conventional zinc oxide as control diet; basal diet + 40 mg/kg of ZnONPs; basal diet + 60 mg/kg of ZnONPs; and basal diet + 100 mg/kg of ZnONPs) and 2 environmental conditions (normal and heat stress). On day 22, birds from each dietary group were divided equally to normal temperature (23 ± 1°C throughout) or heat stress conditions (34 ± 1°C daily for 6 h from 10:00 am until 4:00 pm). From 1 to 42 D of age, the broiler chickens fed 100 mg/kg ZnONPs exhibited lower feed intake and feed conversion ratio than the control. The accumulation of Zn in the liver of broilers was significantly higher among all treatment groups compared to breast and thigh muscle tissues regardless of the temperature conditions. At 40 and 60 mg/kg ZnONPs, the malondialdehyde content increased in thigh muscle of broilers at 7 D postmortem, indicating that ZnONPs potentially inhibited the antioxidant system in muscle tissues. The control and ZnONPs at 40 mg/kg and 60 mg/kg led to low serum corticosterone levels that may be attributed to the antioxidant and antistress properties of Zn. Taken together, although supplementation with ZnONPs at 40 mg/kg and 60 mg/kg alleviated the negative results of heat stress, further research is needed to determine the optimal level of dietary ZnONPs supplementation.
Mother-offspring interaction begins before birth. The foetus is particularly vulnerable to environmental insults and stress. The body responds by releasing excess of the stress hormone cortisol, which acts on glucocorticoid receptors. Hippocampus in the brain is rich in glucocorticoid receptors and therefore susceptible to stress. The stress effects are reduced when the animals are placed under a model wooden pyramid. The present study was to first explore the effects of prenatal restraint-stress on the plasma corticosterone levels and the dendritic arborisation of CA3 pyramidal neurons in the hippocampus of the offspring. Further, to test whether the pyramid environment would alter these effects, as housing under a pyramid is known to reduce the stress effects, pregnant Sprague Dawley rats were restrained for 9 h per day from gestation day 7 until parturition in a wire-mesh restrainer. Plasma corticosterone levels were found to be significantly increased. In addition, there was a significant reduction in the apical and the basal total dendritic branching points and intersections of the CA3 hippocampal pyramidal neurons. The results thus suggest that, housing in the pyramid dramatically reduces prenatal stress effects in rats.
Serotonergic (5-HT) drugs are widely used in the clinical management of mood and anxiety disorders. However, it is reported that acute 5-HT treatment elicits anxiogenic-like behavior. Interestingly, the periaqueductal gray (PAG), a midbrain structure which regulates anxiety behavior - has robust 5-HT fibers and reciprocal connections with the hypothalamic-pituitary-adrenal (HPA) axis. Although the HPA axis and the 5-HT system are well investigated, the relationship between the stress hormones induced by 5-HT drug treatment and the PAG neural correlates of the behavior remain largely unknown. In this study, the effects of acute and chronic treatments with buspirone (BUSP) and escitalopram (ESCIT) on anxiety-related behaviors were tested in an open-field (OF). The treatment effects on PAG c-Fos immunoreactivity (c-Fos-ir) and corticosterone (CORT) concentration were measured in order to determine the neural-endocrine correlates of anxiety-related behaviors and drug treatments. Our results demonstrate that acute BUSP and ESCIT treatments induced anxiogenic behaviors with elevation of CORT compared to the baseline. A decrease of c-Fos-ir was found in the dorsomedial PAG region of both the treatment groups. Correlation analysis showed that the CORT were not associated with the OF anxiogenic behavior and PAG c-Fos-ir. No significant differences were found in behaviors and CORT after chronic treatment. In conclusion, acute BUSP and ESCIT treatments elicited anxiogenic response with activation of the HPA axis and reduction of c-Fos-ir in the dorsomedial PAG. Although no correlation was found between the stress hormone and the PAG c-Fos-ir, this does not imply the lack of cause-and-effect relationship between neuroendocrine effects and PAG function in anxiety responses. These correlation studies suggest that the regulation of 5-HT system was probably disrupted by acute 5-HT treatment.
A possible interaction between glucocorticoids and estrogen-induced increases in brain-derived-neurotrophic factor (BDNF) expression in enhancing depressive-like behaviour has been documented. Here we evaluated the effects of Tualang honey, a phytoestrogen, and 17 β -estradiol (E2) on the depressive-like behaviour, stress hormones, and BDNF concentration in stressed ovariectomised (OVX) rats. The animals were divided into six groups: (i) nonstressed sham-operated control, (ii) stressed sham-operated control, (iii) nonstressed OVX, (iv) stressed OVX, (v) stressed OVX treated with E2 (20 μg daily, sc), and (vi) stressed OVX treated with Tualang honey (0.2 g/kg body weight daily, orally). Two months after surgery, the animals were subjected to social instability stress procedure followed by forced swimming test. Struggling time, immobility time, and swimming time were scored. Serum adrenocorticotropic hormone (ACTH) and corticosterone levels, and the BDNF concentration were determined using commercially available ELISA kits. Stressed OVX rats displayed increased depressive-like behaviour with significantly increased serum ACTH and corticosterone levels, while the BDNF concentration was significantly decreased compared to other experimental groups. These changes were notably reversed by both E2 and Tualang honey. In conclusion, both Tualang honey and E2 mediate antidepressive-like effects in stressed OVX rats, possibly acting via restoration of hypothalamic-pituitary-adrenal axis and enhancement of the BDNF concentration.
This study aimed to determine the effect of neonatal feed restriction on plasma corticosterone concentration (CORT), hippocampal glucocorticoid receptor (GR) expression, and heat shock protein (Hsp) 70 expression in aged male Japanese quail subjected to acute heat stress. Equal numbers of chicks were subjected to either ad libitum feeding (AL) or 60% feed restriction on d 4, 5, and 6 (FR). At 21 (young) and 270 (aged) d of age, birds were exposed to 43 ± 1°C for 1 h. Blood and hippocampus samples were collected to determine CORT and Hsp 70 and GR expressions before heat stress and following 1 h of heat stress, 1 h of post-heat stress recovery, and 2 h of post-heat stress recovery. With the use of real-time PCR and enzyme immunoassay, we examined the hippocampal expression of GR and Hsp 70 and CORT. The GR expression of the young birds increased following heat stress and remained consistent throughout the period of recovery. Conversely, no significant changes were noted on GR expression of aged birds. Although both young and aged birds had similar CORT before and during heat stress, the latter exhibited greater values following 1 and 2 h of recovery. Within the young group, feeding regimens had no significant effect on Hsp 70 expression. However, neonatal feed restriction improved Hsp 70 expression in aged birds. Neonatal feed restriction, compared with the AL group, resulted in higher CORT on d 21 but the converse was noted on d 270. Neonatal feed restriction appears to set a robust reactive hypothalamo-pituitary-adrenal response allowing the development of adaptive, healthy, and resilient phenotypes in aged quail as measured by a higher hippocampal Hsp 70 expression along with lower CORT.
Environmental stressors may influence chicken performance and susceptibility to pathogens, such as Salmonella enteritidis. This study was conducted to determine the effects of heat shock protein (Hsp)70 expression on resistance to Salmonella enteritidis infection in broiler chickens subjected to heat exposure. Chicks were divided into 3 feeding regimens: ad libitum feeding (control); 60% feed restriction on d 4, 5, and 6 (FR60); and 60% feed restriction on d 4, 5, and 6 plus 1,500 mg/kg of quercetin (FR60Q). On d 35, all of the chickens were individually inoculated with 1 mL of Salmonella enteritidis (1.5 × 10(8) cfu/bird) and exposed to an ambient temperature of 37 ± 1°C and 70% RH for 3 h/d. The FR60 and FR60Q chickens had significantly lower Salmonella enteritidis colonization and lower Hsp70 expression than that of the control chickens following the heat exposure period. The least colonization was observed in the FR60Q group (1.38 log(10) cfu/g in the spleen and 1.96 log(10) cfu/g in the cecal content) and the highest was in the control group (2.1 log(10) cfu/g in the spleen and 4.42 log(10) cfu/g in the cecal content). It appears that neonatal feed restriction can enhance resistance to Salmonella enteritidis colonization in heat-stressed broiler chicks, and the underlying mechanism could be associated with the lower expression of Hsp70.
We evaluated the effects of a standardized Labisia pumila var. alata (LPva) extract on body weight change, hydroxysteroid (11-beta) dehydrogenase 1 (HSD11B1) expressions and corticosterone (CORT) level in ovariectomized (OVX) rats. The decoction of LPva has been used for generations among Malay women in Malaysia to maintain a healthy reproductive system.Thirty-six Sprague-Dawley OVX rats were treated orally with LPva extract (10, 20 or 50 mg/kg/day) or estrogen replacement (ERT) for 30 days. Sham operated rats were used as controls. Compared to untreated OVX rats, LPva-treated rats showed less weight gain and had significantly down-regulated HSD11B1 mRNA in liver tissues. HSD11B1 mRNA in adipose tissues increased by 55% (p < 0.05) in OVX rats but normalized in rats treated with LPva. Similarly, there was significant down-regulation (p < 0.05) of protein levels of HSD11B1 in both liver and adipose tissue of LPva and ERT groups, and CORT levels were significantly reduced in both groups of rats. This is the first study ever conducted to evaluate the beneficial effects of LPva in relation to weight gain caused by estrogen insufficiency. Results implied that the bioactive components in LPva extract affect not only HSD11B1 expressions in both adipose and liver tissues but also decrease circulating CORT. The extract should be explored for its potential use as a natural remedy for weight management.
Mitragyna speciosa Korth. leaves have been used for decades as a traditional medicine to treat diarrhea, diabetes and to improve blood circulation by natives of Malaysia, Thailand and other regions of Southeast Asia. Mitragynine is the major active alkaloid in the plant. To date, the role of mitragynine in psychological disorders such as depression is not scientifically evaluated. Hence, the present investigation evaluates the antidepressant effect of mitragynine in the mouse forced swim test (FST) and tail suspension test (TST), two models predictive of antidepressant activity and the effect of mitragynine towards neuroendocrine system of hypothalamic-pituitary-adrenal (HPA) axis by measuring the corticosterone concentration of mice exposed to FST and TST. An open-field test (OFT) was used to detect any association of immobility in the FST and TST with changes in motor activity of mice treated with mitragynine. In the present study, mitragynine at dose of 10 mg/kg and 30 mg/kg i.p. injected significantly reduced the immobility time of mice in both FST and TST without any significant effect on locomotor activity in OFT. Moreover, mitragynine significantly reduced the released of corticosterone in mice exposed to FST and TST at dose of 10 mg/kg and 30 mg/kg. Overall, the present study clearly demonstrated that mitragynine exerts an antidepressant effect in animal behavioral model of depression (FST and TST) and the effect appears to be mediated by an interaction with neuroendocrine HPA axis systems.