Serotonin synthesis inhibition by pre-treatment of p-CPA alters sleep-electrophysiology in an animal model of acute and chronic heat stress

Heat Treatment at an Early Age Has Effects on the Resistance to Chronic Heat Stress on Broilers

This study was conducted to investigate the effects of early heat conditioning on growth performance, liver-specific enzymes (GOT and GPT), neuro-hormones (dopamine and serotonin), stress hormones (corticosterone), and the expression of HSPs (heat shock proteins), HSFs (heat shock factors), and pro-inflammatory cytokines under chronic high temperature. Broilers were raised with commercial feed and supplied with water ad libitum under conventional temperature. We separated the broilers into three groups: the control without any heat exposure (C), chronic heat-stressed group (CH), and early and chronic heat-stressed group (HH). At 5 days of age, the HH group was exposed to high temperatures (40 °C for 24 h), while the remaining groups were raised at a standard temperature. Between days 6 and 20, all three groups were kept under optimal temperature. From 21 to 35 days, the two heat-stressed groups (CH and HH) were exposed to 35 °C. Groups exposed to high temperature (CH and HH) showed significantly lower body weight and feed intake compared to the control. GOT and GPT were lower expressed in the CH and HH groups than the control group. In addition, the protein expressions of HSPs were down-regulated by chronic heat stress (CH and HH groups). The gene expressions of HSP60 and HSF3 were significantly down-regulated in the CH and HH groups, while HSP70 and HSP27 genes were up-regulated only in the HH group compared with the control group. The expression of pro-inflammatory cytokine genes was significantly up-regulated in the HH group compared with the control and CH groups. Thus, exposure of early Heat stress (HS) to broilers may affect the inflammatory response; however, early heat exposure did not have a positive effect on chronic HS of liver enzymes and heat shock protein expression.

Effects of whole-body heat on male germ cell development and sperm motility in the laboratory mouse

This study investigated the effects of high temperatures on male germ cell development and epididymal sperm motility of laboratory mice. In Experiment 1, adult males (n = 16) were exposed to whole-body heat of 37–38°C for 8 h day–1 for 3 consecutive days, whereas controls (n = 4) were left at 23–24°C. In Experiment 2, adult mice (n = 6) were exposed to 37–38°C for a single 8-h period with controls (n = 6) left at 23–24°C. Experiment 2 was conducted as a continuation of previous study that showed changes in spermatozoa 16 h after exposure to heat of 37–38°C for 8 h day–1 for 3 consecutive days. In the present study, in Experiment 1, high temperature reduced testes weights 16 h and 14 days after exposure, whereas by Day 21 testes weights were similar to those in the control group (P = 0.18). At 16 h, 7 and 14 days after exposure, an increase in germ cell apoptosis was noticeable in early and late stages (I–VI and XI–XII) of the cycle of the seminiferous epithelium. However, apoptosis in intermediate stages (VII–X) was evident 16 h after heat exposure (P < 0.05), without any change at other time periods. By 21 days, there were no significant differences between heat-treated groups and controls. Considerably more caspase-3-positive germ cells occurred in heat-treated mice 16 h after heat exposure compared with the control group (P < 0.0001), whereas 8 h after heat in Experiment 2, sperm motility was reduced with a higher percentage of spermatozoa showing membrane damage. In conclusion, the present study shows that whole-body heat of 37–38°C induces stage-specific germ cell apoptosis and membrane changes in spermatozoa; this may result in reduced fertility at particular times of exposure after heating.

Effect of heat stress on the porcine small intestine: a morphological and gene expression study

With the presence of global warming, the occurrence of extreme heat is becoming more common, especially during the summer, increasing pig susceptibility to severe heat stress. The aim of the current study was to investigate changes in morphology and gene expression in the pig small intestine in response to heat stress. Forty eight Chinese experimental mini pigs (Sus scrofa) were subjected to 40 degrees C for 5h each day for 10 successive days. Pigs were euthanized at 1, 3, 6, and 10 days after heat treatment and sections of the small intestine epithelial tissue were excised for morphological examination and microarray analyses. After heat treatment, the pig rectal temperature, the body surface temperature and serum cortisol levels were all significantly increased. The duodenum and jejunum displayed significant damage, most severe after 3 days of treatment. Microarray analysis found 93 genes to be up-regulated and 110 genes to be down-regulated in response to heat stress. Subsequent bioinformatic analysis (including gene ontology and KEGG pathway analysis) revealed the genes altered in response to heat stress related to unfolded protein, regulation of translation initiation, regulation of cell proliferation, cell migration and antioxidant regulation. Heat stress caused significant damage to the pig small intestine and altered gene expression in the pig jejunum. The results of the bioinformatic analysis from the present study will be beneficial to further investigate the underlying mechanisms involved in heat stress-induced damage in the pig small intestine.