Light-at-night exposure affects brain development through pineal allopregnanolone-dependent mechanisms.

The molecular mechanisms by which environmental light conditions affect cerebellar development are incompletely understood. We showed that circadian disruption by light-at-night induced Purkinje cell death through pineal allopregnanolone (ALLO) activity during early life in chicks. Light-at-night caused the loss of diurnal variation of pineal ALLO synthesis during early life and led to cerebellar Purkinje cell death, which was suppressed by a daily injection of ALLO. The loss of diurnal variation of pineal ALLO synthesis induced not only reduction in pituitary adenylate cyclase-activating polypeptide (PACAP), a neuroprotective hormone, but also transcriptional repression of the cerebellar Adcyap1 gene that produces PACAP, with subsequent Purkinje cell death. Taken together, pineal ALLO mediated the effect of light on early cerebellar development in chicks.

Dietary L-serine modifies free amino acid composition of maternal milk and lowers the body weight of the offspring in mice.

The growth of offspring is affected not only by the protein in maternal milk but also by the free amino acids (FAAs) contained in it. L-Serine (L-Ser) is known as an important FAA for the development of the central nervous system and behavioral activity. However, it is not clear whether L-Ser is transported into the pool of FAAs contained in milk and thereby affects the growth of offspring. Using mice, the current study investigated the effects of dietary L-Ser during pregnancy and lactation on milk and plasma FAA composition, as well as on growth, behavior, and plasma FAAs of offspring. Dietary L-Ser did not significantly affect the maternal, anxiety-like, or cognitive behaviors of either the dam or the offspring. The FAA composition notably differed between plasma and milk in dams. In milk, dietary L-Ser increased free L-Ser levels, while glutamic acid, L-alanine, D-alanine and taurine levels were decreased. The body weight of the offspring was lowered by dietary L-Ser. The concentrations of plasma FAAs in 13-day-old offspring (fed only milk) were not altered, but 20-day-old offspring (fed both milk and parental diet) showed higher plasma L-Ser and D-Ser concentrations as a result of the dietary L-Ser treatment. In conclusion, the present study found that dietary L-Ser transported easily from maternal plasma to milk and that dietary L-Ser treatment could change the FAA composition of milk, but that an enhanced level of L-Ser in milk did not enhance the plasma L-Ser level in the offspring.

Orally Administered D-Aspartate Depresses Rectal Temperature and Alters Plasma Triacylglycerol and Glucose Concentrations in Broiler Chicks.

L-Aspartate (L-Asp), D-aspartate (D-Asp) or their chemical conjugates plays important physiological roles in regulating food intake, plasma metabolites and thermoregulation in animals. However, there are very few studies available in layers and no reports have been found in broilers. Broilers are very important commercial birds for meat production, so effects of L- or D-Asp in broilers would provide new physiological insight of this strain. Therefore, the purpose of this study was to determine the effect of oral administration of L- or D-Asp on feed intake, rectal temperature and some plasma metabolites in broiler chicks. Broiler chicks (5 days old) were orally administered with different doses (0, 3.75, 7.5 and 15 mmol/kg body weight) of L- or D-Asp. At 120 min after administration of L- or D-Asp, the blood was immediately collected through the jugular vein. The rectal temperature of chicks was measured at 30, 60 and 120 min after administration using a digital thermometer with an accuracy of ±0.1°C, by inserting the thermistor probe in the rectum to a depth of 2 cm. A repeated-measures two-way ANOVA was applied for the analysis of feed intake and rectal temperature. Plasma metabolites were statistically analyzed by one-way ANOVA and regression equations. The study showed that oral administration of both L- and D-Asp did not alter feed intake. However, D-Asp, but not L-Asp, dose-dependently decreased the rectal temperature in chicks. It was also found that D-Asp increased plasma glucose and decreased triacylglycerol concentrations. The changes in plasma metabolites further indicate that D-Asp treatment modulates the energy metabolism in broiler chicks. In conclusion, D-Asp may be a beneficial nutrient not only for layers but also for broilers, since orally administered D-Asp lowered rectal temperature without reducing feed intake.

Transcriptomic features associated with energy production in the muscles of Pacific bluefin tuna and Pacific cod.

Bluefin tuna are high-performance swimmers and top predators in the open ocean. Their swimming is grounded by unique features including an exceptional glycolytic potential in white muscle, which is supported by high enzymatic activities. Here we performed high-throughput RNA sequencing (RNA-Seq) in muscles of the Pacific bluefin tuna (Thunnus orientalis) and Pacific cod (Gadus macrocephalus) and conducted a comparative transcriptomic analysis of genes related to energy production. We found that the total expression of glycolytic genes was much higher in the white muscle of tuna than in the other muscles, and that the expression of only six genes for glycolytic enzymes accounted for 83.4% of the total. These expression patterns were in good agreement with the patterns of enzyme activity previously reported. The findings suggest that the mRNA expression of glycolytic genes may contribute directly to the enzymatic activities in the muscles of tuna.

Comparison of centrally injected tryptophan-related substances inducing sedation in acute isolation stress-induced neonatal chicks.

In the present study, we first focused on the function of l-tryptophan (TRP) metabolites which are synthesized in different metabolic pathways, namely, the kynurenine (KYN) pathway and serotonin (5-HT) pathway during an acute isolation stress. When l-TRP metabolites were intracerebroventricularly injected on an equimolar basis (100 nmol), 5-HT induced a sedative effect in neonatal chicks. Additionally, plasma corticosterone, dopamine, 5-HT, and its metabolite 5-hydroxyindoleacetic acid concentrations were increased in the diencephalon of the 5-HT treated group compared with other groups. Second, the two doses (400 or 800 nmol) of l- and d-TRP were compared under a corticotrophin-releasing hormone-augmented social isolation stress. When comparing the efficacy between l- and d-TRP against stress behavior, both amino acids had a similar effect and quickly suppressed distress vocalizations. Finally, d-amino acid levels in the diencephalon and telencephalon were measured but d-TRP was not found. These results indicate that l- and d-TRP induce the same effect in attenuating stress but the mode of action of TRP derivatives, namely 5-HT differs during an acute isolation stress in neonatal chick. The absence of d-TRP in the diencephalon further suggests that instead of being an endogenous factor it may play role as a pharmacological factor.

Expression and regulation of Foxa2 in the rat uterus during early pregnancy.

The forkhead box a (Foxa) protein family has been found to play important roles in mammals. Recently, the expression of Foxa2 was reported in the mouse uterus, and it was reported to be involved in regulation of implantation. However, the regulation of Foxa2 expression in the uterus is still poorly understood. Therefore, the present study was conducted to investigate the expressional profiles of Foxa2 in the rat uterus during the estrus cycle and pregnancy. Furthermore, the effect of steroid hormones and Hedgehog protein on the expression of Foxa2 was analyzed in vivo and in vitro. In this study, the level of expression of Foxa2 was low in the rat uterus during the different stages of the estrus cycle. However, the expression increased transiently during early pregnancy at 3.5 days post coitus (dpc) and decreased at 5.5 dpc. In ovariectomized rats, P4 treatment had no effect on the expression of Foxa2 compared with the expression in control animals. Moreover, the expression of Foxa2 in cultured epithelial cells was not increased by P4 treatment in vitro. However, Foxa2 expression was significantly decreased in the rat uterus after 24 h of E2 treatment. Treatment of cells with a recombinant Hedgehog protein significantly increased the expression of Foxa2. These results suggest that the expression of Foxa2 may transiently increase just before the implantation and it may be regulated by E2 and Hedgehog protein.

Oral administration of D-aspartate, but not L-aspartate, depresses rectal temperature and alters plasma metabolites in chicks.

AIMS: L-Aspartate (L-Asp) and D-aspartate (D-Asp) are physiologically important amino acids in mammals and birds. However, the functions of these amino acids have not yet been fully understood. In this study, we therefore examined the effects of L-Asp and D-Asp in terms of regulating body temperature, plasma metabolites and catecholamines in chicks. MAIN METHODS: Chicks were first orally administered with different doses (0, 3.75, 7.5 and 15 mmol/kg body weight) of L- or D-Asp to monitor the effects of these amino acids on rectal temperature during 120 min of the experimental period. KEY FINDINGS: Oral administration of D-Asp, but not of L-Asp, linearly decreased the rectal temperature in chicks. Importantly, orally administered D-Asp led to a significant reduction in body temperature in chicks even under high ambient temperature (HT) conditions. However, centrally administered D-Asp did not significantly influence the body temperature in chicks. As for plasma metabolites and catecholamines, orally administered D-Asp led to decreased triacylglycerol and uric acid concentrations and increased glucose and chlorine concentrations but did not alter plasma catecholamines. SIGNIFICANCE: These results suggest that oral administration of D-Asp may play a potent role in reducing body temperature under both normal and HT conditions. The alteration of plasma metabolites further indicates that D-Asp may contribute to the regulation of metabolic activity in chicks.

Metabolism of amino acids differs in the brains of Djungarian hamster (P. sungorus) and Roborovskii hamster (P. roborovskii).

Djungarian hamster (P. sungorus) and Roborovskii hamster (P. roborovskii) belong to the same genus of phodopus. Roborovskii hamster shows high locomotor activity and low level of dopamine (DA) in the brain. Administration of L-tyrosine, a precursor of DA, decreases locomotor activity in Roborovskii hamsters. However, the amino acid metabolism in relation to the hyperactivity is not yet well known. In the present study, L- and D-amino acid concentrations in the brain, liver, and plasma in Djungarian and Roborovskii hamsters were investigated during day and night times to explain the possible difference in hyperactivity between them. Most of the examined amino acids were higher in the night time when hamsters are active compared to those in day time. L- and D-tyrosine concentrations were higher in the liver of Roborovskii hamsters than in Djungarian hamsters. Furthermore, brain concentration of D-tyrosine was higher in the Roborovskii than in Djungarian hamsters, but no significant difference was observed for L-tyrosine concentrations between the two species. These results suggest that the conversion of L-tyrosine to D-tyrosine in the brain of Roborovskii hamster may be higher than in Djungarian hamster, which may cause low DA concentration and hyperactivity in Roborovskii hamster. On the other hand, L- and D-serine, which are known as sedative factors, were lower in Roborovskii hamsters than Djungarian hamster. These results suggest that species-specific regulation in amino acid metabolism may contribute to hyperactivity in Roborovskii hamsters.

Central injection of L- and D-aspartate attenuates isolation-induced stress behavior in chicks possibly through different mechanisms.

Intracerebroventricular (i.c.v.) injection of L- and D-aspartate (L- and D-Asp) has been shown to have a sedative effect with and without a hypnotic effect, respectively, in neonatal chicks experiencing isolation stress. However, the mechanisms of the different stress-attenuating functions of L- and D-Asp have not yet been fully clarified. In the present study, we investigated the involvement of the N-methyl-D-aspartate (NMDA) receptor in order to reveal the receptor-mediated function of L- and D-Asp. To reveal whether L-and D-Asp act through the NMDA receptor, (+)-MK-801, which is an antagonist of NMDA receptors, was used in the current study. In experiment 1, the chicks were injected i.c.v. with either saline, (+)-MK-801, L-Asp or L-Asp plus (+)-MK-801. The sedative and hypnotic effects induced by L-Asp were blocked by co-administration with (+)-MK-801. In experiment 2, the chicks were injected i.c.v. with either saline, (+)-MK-801, D-Asp or D-Asp plus (+)-MK-801. Importantly, the sedative effects induced by D-Asp were shifted to hypnotic effects by co-administration with (+)-MK-801. Taken together, L-Asp could induce sedative and hypnotic effects for stress behaviors through the NMDA receptor, but the attenuation of stress behaviors by D-Asp might be via simultaneous involvement of other receptors besides the NMDA receptor in this process. These differences may explain the different functional mechanisms of L- and D-Asp in the central nervous system.

Evolutionary changes of multiple visual pigment genes in the complete genome of Pacific bluefin tuna.

Tunas are migratory fishes in offshore habitats and top predators with unique features. Despite their ecological importance and high market values, the open-ocean lifestyle of tuna, in which effective sensing systems such as color vision are required for capture of prey, has been poorly understood. To elucidate the genetic and evolutionary basis of optic adaptation of tuna, we determined the genome sequence of the Pacific bluefin tuna (Thunnus orientalis), using next-generation sequencing technology. A total of 26,433 protein-coding genes were predicted from 16,802 assembled scaffolds. From these, we identified five common fish visual pigment genes: red-sensitive (middle/long-wavelength sensitive; M/LWS), UV-sensitive (short-wavelength sensitive 1; SWS1), blue-sensitive (SWS2), rhodopsin (RH1), and green-sensitive (RH2) opsin genes. Sequence comparison revealed that tuna's RH1 gene has an amino acid substitution that causes a short-wave shift in the absorption spectrum (i.e., blue shift). Pacific bluefin tuna has at least five RH2 paralogs, the most among studied fishes; four of the proteins encoded may be tuned to blue light at the amino acid level. Moreover, phylogenetic analysis suggested that gene conversions have occurred in each of the SWS2 and RH2 loci in a short period. Thus, Pacific bluefin tuna has undergone evolutionary changes in three genes (RH1, RH2, and SWS2), which may have contributed to detecting blue-green contrast and measuring the distance to prey in the blue-pelagic ocean. These findings provide basic information on behavioral traits of predatory fish and, thereby, could help to improve the technology to culture such fish in captivity for resource management.

Effect of PPARß/δ agonist on the placentation and embryo-fetal development in rats.

BACKGROUND: The present study was conducted to evaluate the developmental toxicity in the endometrium and placenta due to GW501516 administration by gavage to pregnant rats. METHODS: GW501516 was orally administered repeatedly to pregnant rats from gestation day (GD) 6 to 17 at a dose of 0, 30, and 100 mg/kg/day. In next study, GW501516 was also orally administered to pregnant rats on GD 7, 8, 9, 10, or 11 at a single dose of 275 or 350 mg/kg. In these studies, caesarean section was performed to examine the pregnancy outcome on GD21. Additionally, GW501516 was orally administered to pregnant rats on GD 10 at a single dose of 275 mg/kg. Placentae were subjected for temporal histological examinations on GD 11, 13, 15, or 17. RESULTS: Placental malformation was induced by repeated administration of GW501516 at a dose of 100 mg/kg/day. Single oral administration of GW501516 at a dose of 275 and/or 350 mg/kg on GD 8, 9, 10, or 11 induced placental malformation, whereas GW501516 administered on GD 10 was the most effective for increasing placental malformation. Histopathologically, single oral administration of GW501516 on GD 10 induced cystic degeneration associated with cellular lysis of glycogen cells started from GD 15 in the basal zone. CONCLUSIONS: High frequency of placental malformation was observed by the administration of GW501516. From GD 8 to 11, especially GD 10, is more sensitive period to induce the placental malformation.

Changes in collagen fiber content and hepatic stellate cell distribution in the liver of chick embryos and growing chickens.

The content of collagen and the distribution of hepatic stellate cells (HSCs) were studied to elucidate the occurrence of sex-dependent variations in the liver of developing embryos and growing chickens. Chick embryos from embryonic days (e) 12 to e20 and chicks at 1, 4 and 8 weeks were analyzed. Liver tissue was processed using NaOH maceration and freeze-dried to obtain the collagen fiber specimens. HSCs were identified by double fluorescent immunohistochemistry for desmin and vimentin. There were no sex-dependent variations in the percentage of collagen fiber per liver weight and HSC area during embryonic stages. However, the content of collagen fiber increased during embryonic development in both sexes. On the other hand, the area of HSCs significantly increased in growing males but did not show any change in females. Importantly, sex differences were observed in both collagen fiber content and HSC area in the liver at 8 weeks. These results indicate that the occurrence of collagen content variations takes place at 8 weeks in chicken liver, suggesting that a sex-dependent hormone may play an important role on the collagen production of HSCs in the growing chicken liver.

Expression of peroxisome proliferator-activated receptor isoforms in the rat uterus during early pregnancy.

Peroxisome proliferator-activated receptors (PPARs) play an important role in different compartments of the female reproductive system in rodents and humans. However, expressional profiles and physiological functions of PPARs in the endometrium prior to the placentation are not well understood. In this study, we determined expressional profiles of the PPARs during early pregnancy. Immunocytochemistry revealed that both PPARα and PPARß/δ were strongly detected in the endometrial stroma on days 4.5-6.5 of pregnancy, which is just a starting time of implantation. Delayed implantation animal model showed that the expressions of PPARα and PPARß/δ occurred after the initiation of implantation in the endometrial stroma. Moreover, an in vitro decidualization model further revealed that the expression of PPARα increased in the cultured rat endometrial stromal cells at 24 h after the decidualization treatment, but the expression of PPARß/δ was delayed and increased at 48 h after the treatment. PPARγ was expressed in the endometrial stroma and its expression decreased significantly at 2.5 days post-coitum and maintained a low level of expression during the period of implantation. These results indicate that PPARα is expressed and induced by the initiation of implantation, prior to the expression of PPARß/δ in decidualized endometrium. Increasing expression of PPARγ during fertilization and its decline during the period of implantation further suggest that PPARs may play important roles during early pregnancy.

Identification, localization and expression of LPXRFamide peptides, and melatonin-dependent induction of their precursor mRNA in the newt brain.

The existence of RFamide peptides with a C-terminal LPXRFamide (X=L or Q) motif has been identified in the brain of various vertebrate species. However, the presence of LPXRFamide peptides in the urodele brain is not yet known. In this study, we cloned a cDNA encoding the precursor of LPXRFamide peptides from the newt brain by a combination of 3' and 5' rapid amplification of cDNA ends. The deduced LPXRFamide peptide precursor consisted of 233 amino acid residues, encoding four putative LPXRFamide peptides. All the peptide sequences were flanked by a glycine C-terminal amidation signal and basic amino acid on each end as an endoproteolytic site. Mass spectrometric analyses detected a nonapeptide, two decapeptides and an octapeptide produced from the precursor polypeptide in the brain as endogenous ligands. In situ hybridization further revealed the cellular localization of newt LPXRFamide (nLPXRFa) precursor mRNA in the suprachiasmatic nucleus (SCN) in the newt hypothalamus. Immunocytochemistry showed a cluster of cell bodies restricted to the SCN and their terminals in the median eminence. To understand the regulatory mechanism of nLPXRFa peptide expression, we further analyzed the effect of melatonin on the expression of nLPXRFa precursor mRNA. Melatonin administration to newts increased the expression of nLPXRFa precursor mRNA in the diencephalon. These results indicate that the urodele hypothalamus possesses LPXRFamide peptides and the expression of LPXRFamide peptides is regulated by melatonin. The localization of nLPXRFa peptides further suggests that these peptides may be involved in the regulation of pituitary hormone release in newts.