Impact of In Ovo Leptin Injection and Dietary Protein Levels on Ovarian Growth Markers and Early Folliculogenesis in Post-Hatch Chicks (Gallus gallus domesticus).

Genetically bred for rapid growth, broiler breeder hens develop obesity and ovarian dysfunction when fed ad libitum, resembling a condition that resembles human polycystic ovary syndrome (PCOS). Nutritional control applies to post-hatched chicks from one week onward to prevent the development of a PCOS-like phenotype in adult broilers. This study investigated the impact of a growth marker, leptin, and post-hatch nutritional intake on early-life ovarian function. Fertile broiler eggs were injected in ovo with physiological saline solution or 5 µg of leptin and then incubated. After hatching, female chicks were fed ad libitum a diet containing low protein (17% low crude protein (LP)) or standard protein (22% standard crude protein (SP)). Tissues were collected from 7- and 28-day-old chicks for RT-qPCR and histological analysis. In contrast to the LP diet, the SP diet suppressed the mRNA expression of ovarian growth markers essential for folliculogenesis in post-hatched chicks. Leptin injection did not influence ovarian growth markers but increased pituitary gonadotropin transcripts in 7-day-old chicks fed with LP diet. No treatment effects on follicle activation were noted on day 7, but by day 28, in ovo leptin-treated LP-fed chicks exhibited a higher percentage of primary follicles. These changes may have resulted from the early upregulation of genes by leptin during the first week, including pituitary gonadotropins and ovarian leptin receptors. The decline in ovarian growth markers with the SP diet highlights the importance of precise post-hatch protein calculation, which may influence future ovarian function in animals. These findings may contribute to future dietary strategies to enhance broiler reproduction.

Molecular form identification of anterior pituitary gland-secreted prolactin in chicken.

Endocrine changes during bird reproduction are well documented. Prolactin (PRL) exhibits a strong relationship between incubation and broody behavior. The molecular forms of PRL in the anterior pituitary gland during the reproductive cycle have already been previously identified but not those in the secreted form. To identify the molecular forms of secreted PRL during the reproductive cycle, we thus monitored the physiological status and incubation behavior of 10 Silkie hens by a video recording system over 1-2 years. Nine out of ten mature hens exhibited incubation behavior multiple times during the experiment. Ten hens demonstrated two interesting features. In a typical clutch, hens spent 10-15 min in the nest to lay an egg. Once they spent over 1 h in the nest, the nest occupancy increased incrementally. This shift in the nest occupancy occurred 7-10 days before the incubation onset and was highly repeatable. Based on the behavior of the hens, we cultured the anterior pituitary gland during four stages (premature non-laying, laying, trans, and incubation) with physiological PRL-releasing factor, vasoactive intestinal peptide (VIP). Based on our two-dimensional protein analysis, glycosylated PRL (G-PRL) displayed several isoforms with varying isoelectric points (pI), whereas we could detect one primary signal for non-glycosylated PRL (NG-PRL). However, 3-4 NG-PRL isoforms were detected in the anterior pituitary gland. These results suggested that secreted PRL, especially from the trans and incubation stages, contains various isoforms and it is post-translationally glycosylated and phosphorylated.

Long-term intake of α-glycerophosphocholine (GPC) suppresses microglial inflammation and blood-brain barrier (BBB) disruption and promotes neurogenesis in senescence-accelerated mice prone 8 (SAMP8).

We evaluated the effects of long-term glycerophosphocholine (GPC) intake on microglia, the blood-brain barrier (BBB), and neurogenesis in senescence-accelerated mice prone 8 (SAMP8). The GPC intake suppressed microglial activation and BBB disruption and sustained doublecortin-positive cells in the hippocampus. The results indicate that GPC intake exerts anti-inflammatory and neuroprotective effects in the brain of aged mice.

Association of Fatty Acid Desaturase 1 rs174547 Polymorphism with the Composition of Long-Chain Polyunsaturated Fatty Acids in Serum Glycerophospholipids during Pregnancy.

The increase in fetal requirements of long-chain polyunsaturated fatty acids (LCPUFAs) during pregnancy alters maternal fatty acid metabolism, and therefore, fatty acid desaturase (FADS) gene polymorphisms may change blood fatty acid composition or concentration differently during pregnancy. We investigated the relationship between a FADS1 single-nucleotide polymorphism (SNP) and maternal serum LCPUFA levels in Japanese pregnant women during the first and third trimesters and at delivery. Two hundred and fifty-three pregnant women were included, and fatty acid compositions of glycerophospholipids in serum (weight %) and the FADS1 SNP rs174547 (T/C) were analyzed. LCPUFAs, including arachidonic acid (ARA) and docosahexaenoic acid (DHA), significantly decreased from the first to the third trimester of pregnancy. Furthermore, DHA significantly decreased from the third trimester of pregnancy to delivery. At all gestational stages, linoleic acid (LA) and α-linolenic acid were significantly higher with the number of minor FADS1 SNP alleles, whereas γ-linolenic acid and ARA and the ARA/LA ratio were significantly lower. DHA was significantly lower with the number of minor FADS1 SNP alleles only in the third trimester and at delivery, suggesting that genotype effects become more obvious as pregnancy progresses.

Current Situation of Dietary Choline in Japan.

Nutrients are sometimes handled differently in different countries. Choline is not yet a popular research topic, and it may be difficult to recognize its importance as a nutrient. Choline, which is the topic of this paper, is handled differently in different countries. However, the one thing that can be said to be common among all countries is that no country has a sufficient intake of choline that meets the target level.

Regulation of Prolactin Release at the End Stage of Chicken Embryogenesis.

Difference of onset of increase of PRL content in the anterior pituitary gland and plasma PRL concentration during the late stage of chicken embryogenesis is well known. To investigate the disagreement, changes in PRL content and PRL mRNA levels, and the effects of vasoactive intestinal polypeptides (VIP) on PRL release and PRL mRNA expression were examined using western blot analysis and real-time PCR quantification. Changes in SPRL content were strongly correlated with PRL mRNA levels. The increase in PRL content on day 17 of incubation may be caused by the increase in PRL mRNA levels on day 16 of incubation. Additionally, the effects of VIP on PRL release from the embryonic anterior pituitary gland were not observed until day 18 of embryogenesis. These results suggest that increased levels of PRL mRNA and PRL content in the anterior pituitary gland are closely correlated. However, the increased expression of PRL mRNA observed on day 17 and the initiation of PRL release from the anterior pituitary gland on day 19 were differentially regulated. According to the results of western blot analysis, the proportion of glycosylated PRL (G-PRL) and non-glycosylated PRL (NG-PRL) in the anterior pituitary gland at the end stage of development differed from the proportion of PRL released from the anterior pituitary gland. According to the results of two-dimensional western blot analysis, no isoforms with different isoelectric points were detected in the culture medium on days 19 and 20. These data suggest that the peptide chains of G-PRL and NG-PRL were not modified. In conclusion, the differentiation of PRL-producing cells and the maturation of the hypothalamus and anterior pituitary gland were completed at the end stage of incubation, and that different factors regulated the initiation of PRL mRNA expression before day 18 of incubation.

Leptin Promotes Primordial Follicle Activation by Regulating Ovarian Insulin-like Growth Factor System in Chicken.

Leptin and insulin-like growth factor 1 (IGF-1) regulate follicle development and reproduction in vertebrates. This study investigated the role played by leptin and IGF-1 in primordial follicle activation in the ovary of 7-day-old chicks. Different doses of leptin were intraperitoneally administrated to female layer chicks, and further analyses were performed. While leptin administration did not affect hepatic leptin receptor (LEPR), growth hormone receptor (GHR), or IGF-1, the lower dose of leptin significantly increased the messenger RNA (mRNA) expression of IGF-1, IGF-1 receptor, and IGF-binding protein (IGFBP)-2 and attenuated anti-Müllerian hormone (AMH) gene expression in the ovary. Furthermore, the ovaries of the same age chicks were challenged with leptin and/or IGF-1 in vitro. Leptin at a lower dose increased the mRNA expression of IGF-1, LEPR, and leptin; 100 ng/mL leptin and 10 ng/mL IGF-1 alone or combined with leptin reduced IGFBP-2 mRNA expression. AMH gene expression was also reduced by all doses except 10 ng/mL leptin. Histological studies showed that a lower dose of leptin injection induced the primordial follicle growth in the ovary in vivo, and the number of primordial follicles was higher in all leptin treatments over control in vitro. Moreover, the luciferase assay revealed that leptin enhanced IGF-1 promoter activity in LEPR-expressing CHO-K1 cells. Collectively, these results indicate that leptin directly affects the IGF-1/IGFBP system and promotes primordial follicular growth in the ovary of early posthatch chicks. In addition, the follicular development by leptin-induced IGF-1 is, at least in part, caused by the suppression of AMH in the ovary.

Comparison of the Physical Characteristics and Behavior in ABC Transporter A1, A7 or Apolipoprotein E Knockout Mice with Lipid Transport Dysfunction.

The physical characteristics and behavior of the ATP-binding cassette (ABC) A1, A7, and apolipoprotein (apo) E knockout (KO) mice with lipid transport dysfunction were investigated. These KO mice exhibited adequate growth, and their body masses increased steadily. No remarkable changes were observed in their blood pressure and heart rate. However, there was a slight increase in the heart rate of the ABCA7 KO mice compared with that of the wild-type (WT) mice. ABCA1 and apoE KO mice showed hypo- and hyper-cholesterol concentrations in the plasma, respectively. With regard to the cerebrum, however, the weight of the ABCA1 KO mice was lighter than those of the other genotypes. Furthermore, the cholesterol, triglyceride and phospholipid concentrations, and fatty acid composition were generally similar. Compared with the WT mice, ABCA1 KO mice stayed for a shorter time in the closed arm of the elevated plus maze, and performed worse in the initial stage of the Morris water maze. To thermal stimuli, the ABCA1 and apoE KO mice showed hyper- and hypo-sensitivities, respectively. Only the response of the ABCA1 KO mice was significantly inhibited by pretreatment with indomethacin. A low concentration of the prostaglandin E metabolites was detected in the plasma of the ABCA1 KO mice. Thus, ABCA1 is thought to play a specific role in the neural function.

Leptin Modulates the mRNA Expression of Follicle Development Markers in Post-hatch Chicks in an Age-Dependent Manner.

Leptin is involved in regulating reproductive function in chickens, and the development of the leptin system is initiated during the early embryonic stage; however, whether leptin has a specific role in regulating the ovarian development in early post-hatch days is still not fully understood. This study investigated the expression of ovarian functional markers in growing juvenile chickens, along with the effects of leptin on gene expression in the hypothalamus-pituitary-gonadal (HPG) axis on specific ovarian-remodeling days. Leptin receptor (LEPR), follicle-stimulating hormone receptor (FSHR), and the mRNA expression of aromatase (CYP19A1) tended to increase with age in the ovaries of growing chicks. In the ovaries of 7-day-old chicks, intraperitoneally injected leptin significantly increased the mRNA expressions of LEPR, FSHR, and CYP19A1, and this resulted in the increased serum estradiol levels. However, leptin had no effect on hypothalamic LEPR, gonadotropin-releasing hormone 1 (GnRH1), or gonadotropin-inhibitory hormone (GnIH) mRNAs; however, in the pituitary gland, leptin significantly increased the mRNA expression of luteinizing hormone beta subunit (LHB) but had no effect on the mRNA expression of follicle-stimulating hormone beta subunit (FSHB). In 28-day-old chicks, hypothalamic and pituitary mRNAs were unaffected by leptin administration, except hypothalamic LEPR mRNA that was upregulated by a high dose of leptin. In the ovary, leptin dose-dependently decreased the mRNA expression of LEPR; low doses of leptin significantly increased the mRNA expression of FSHR, whereas high doses significantly decreased this expression; leptin did not affect the mRNA expression of CYP19A1; and high leptin doses significantly reduced the serum estradiol levels. Collectively, the results of this study show that leptin modulates ovarian development and folliculogenesis marker genes by primarily acting on ovaries on the specific ovarian-remodeling days in post-hatch chicks, which may alter folliculogenesis and ovarian development toward puberty in chicken.

Are lifestyle factors significantly associated with self-rated health among Japanese female healthcare students?

BACKGROUND: Self-rated health (SRH), a subjective perception of an individual's overall health, is widely used in public health assessment. The transition from adolescence to young adulthood is a critical period involving substantial changes in lifestyle and dietary habits. Therefore, it is important to understand SRH among young Japanese females. The present study aimed to investigate the relationships between SRH among female healthcare students and their lifestyle factors, such as living status (living with others or living alone), smoking habit, alcohol consumption, frequency of breakfast consumption (FBC), physical activity, insomnia, and physique recognition. METHODS: A cross-sectional survey was conducted on 1101 female healthcare students in Japan. The body mass index was calculated from the body height and weight using data from periodic health examinations. Self-reported sociodemographic, lifestyle or dietary habits, physical activity, and SRH were used through a self-administered questionnaire. Participants were classified as having either good SRH (excellent, very good, or good) or impaired SRH (fair or poor). Multivariate logistic regression analysis was performed to investigate the independent relationships between SRH and lifestyle factors. RESULTS: A total of 11.4% participants demonstrated impaired SRH. Multivariate logistic regression analysis showed that the University of California Los Angeles activity score, Athens Insomnia Scale, and physique recognition were associated with SRH. CONCLUSIONS: It was suggested that public health activities that consider physical activity, sleep, and physique recognition may help maintain and improve SRH in female university students in Japan.

Distribution of 5-Methyltetrahydrofolate and Folic Acid Levels in Maternal and Cord Blood Serum: Longitudinal Evaluation of Japanese Pregnant Women.

"Total" folate in blood has usually been measured to evaluate the folate status of pregnant women. However, folate is composed of many metabolites. The main substrate is 5-methyltetrahydrofolate (5-MTHF), with folic acid (FA) representing a very small component as an unmetabolized species in blood. We longitudinally evaluated 5-MTHF, FA and total homocysteine in maternal and cord blood from Japanese pregnant women. Subjects were 146 pregnant women who participated in the Chiba study of Mother and Child Health (C-MACH) prospective cohort study. Sera were obtained in early and late pregnancy, at delivery, and from cord blood. Species levels were measured by isotope-dilution mass spectrometry. Both 5-MTHF and FA levels were lower than reported levels from pregnant women in populations from countries with mandatory FA fortification. As gestational age progressed, serum 5-MTHF levels decreased, whereas serum FA levels were slightly reduced only at delivery compared to early pregnancy. A significant negative association between serum 5-MTHF and total homocysteine was shown at all examined times, but no associations with FA were evident. At delivery, cord 5-MTHF was significantly higher than maternal levels, while FA again showed no significant correlation. These results suggest that 5-MTHF is actively transported to the fetus through placental transporters and may reflect folate status during pregnancy as a physiologically important species.

Relationships Between the Purposes of Taurine-Contained Nutritional Drink Intake and Lifestyle Habits: A Cross-Sectional Survey of Workers in Japan.

This study surveyed that the relationship between the frequencies of intake of taurine-contained nutritional drinks (TCND), and lifestyle and the purposes of intake it. The study was conducted a cross-sectional survey using 265 people (203 male, 62 female) aged 18-64 worked in two companies in Mie Prefecture, Japan between December 2017 and February 2018. The questionnaires gathered characteristics, demographic, socioeconomic, lifestyle habits and purpose of TCND intake. We divided the frequency of intake of TCND of at least a few times every month as the high-frequency TCND (HF-TCND) group, and the remaining as the low-frequency TCND (LF-TCND) group. Multivariate logistic regression analysis was used to investigate the relationship between characteristics, demographic, socioeconomic, lifestyle habits and purpose of TCND intake and HF-TCND after controlling for individual variables. Of all participants, 13.4% was evaluated as HT-CND. 16.3% for male or 4.3% for female were evaluated as HF-TCND (p < 0.05). The most reason for frequent choosing a TCND was fatigue recovery. Logistic regression analysis showed that sex, occupation, purpose of TCND intake and stressful are related to HF-TCND. Our study indicates that purpose of TCND intake, such as fatigue recovery and reducing stress, may partly affect the frequency of intake of TCND. Therefore, we must continue to show scientific evidence for taurine by enlightenment activity etc.

Identification of hypothalamic genes in associating with food intake during incubation behavior in domestic chicken.

The molecular mechanism underlying in the onset and maintenance of incubation behavior are not fully understood, and it is still unknown the reason why White Leghorn, a layer strain, hens never display incubation behavior. Therefore, to explore specific hypothalamic genes regulating incubation behavior, cap analysis of gene expression (CAGE) were applied to comparison between incubating Silkie and laying White Leghorn hens. In addition, mRNA expression of some differentially expressed genes (DEGs) and melanocortinergic appetite genes including agouti-related peptide (AgRP) and pro-opiomelanocortin (POMC) was also analyzed on Silkie hens under natural anorexia and starvation. The CAGE identified 217 hypothalamic DEGs in incubating Silkie hens, and that of two, transthyretin (TTR) and prolactin-releasing peptide (PrRP), suggested as appetite gene, were markedly up- and down-regulated in incubating hens, respectively. In addition, AgRP and POMC expression also increased in incubating bird. mRNA expression of TTR, PrRP, and appetite genes were not differed significantly by starvation, although TTR mRNA expression was relatively high in fasting hens. Consequently, transcriptome by CAGE identified a number of hypothalamic genes differentially expressed by incubation behavior in Silkie hens. Of these, it is suggested that TTR and PrRP may, at least in part, be related to adaptation to natural anorexia in incubating Silkie chickens.

Determination of Polymorphisms in Pituitary Genes of the Native Afghani Naked Neck Chicken.

We investigated means to improve the production of the indigenous Naked Neck chicken in Afghanistan. Specifically, we analyzed single nucleotide polymorphisms (SNPs) in the prolactin (PRL) (24 bp indel), growth hormone (GH) (T185G), and pituitary specific transcript factor 1 (PIT-1) (intron 5) genes. Blood samples were collected from 52 birds and genomic DNA was extracted. Polymorphisms in the mentioned loci were analyzed by PCR, allele-specific PCR, and PCR-restriction fragment length polymorphism (RFLP) using TaqI and MspI endonucleases. Cloning followed by DNA sequencing was performed to ascertain the accuracy of the PCR-RFLP analysis for PIT-1.Two alleles were found for the PRL 24 bp indel, GH (T185G), and PIT-1/TaqI, with the following respective allelic frequencies: PRL-In 0.64 and PRL-Del 0.36, GH-T 0.91 and GH-G 0.09, and PIT-1-A 0.64 and PIT-1-B 0.36. Regarding the PIT-1/MspI polymorphism, three novel MspI recognition sites, as well as two reported MspI recognition sites, were detected in intron 5. Moreover, during sequence screening, two novel SNPs were found that generated restriction sites for MseI. Therefore, our results suggest that the PRL indel, GH T185G, and PIT-1/TaqI polymorphisms may be used as selection markers for Afghanistan Naked Neck chickens. Intron 5 of PIT-1 in the Afghani Naked Neck chicken was highly polymorphic compared to the reported Gallus gallus PIT-1 gene (GenBank accession no. NC_006088.4).

AMP-Activated Protein Kinase Mediates the Effect of Leptin on Avian Autophagy in a Tissue-Specific Manner.

Autophagy, a highly conserved intracellular self-digestion process, plays an integral role in maintaining cellular homeostasis. Although emerging evidence indicate that the endocrine system regulates autophagy in mammals, there is still a scarcity of information on autophagy in avian (non-mammalian) species. Here, we show that intracerebroventricular administration of leptin reduces feed intake, modulates the expression of feeding-related hypothalamic neuropeptides, activates leptin receptor and signal transducer and activator of transcription (Ob-Rb/STAT) pathway, and significantly increases the expression of autophagy-related proteins (Atg3, Atg5, Atg7, beclin1, and LC3B) in chicken hypothalamus, liver, and muscle. Similarly, leptin treatment activates Ob-Rb/STAT pathway and increased the expression of autophagy-related markers in chicken hypothalamic organotypic cultures, muscle (QM7) and hepatocyte (Sim-CEL) cell cultures as well as in Chinese Hamster Ovary (CHO-K1) cells-overexpressing chicken Ob-Rb and STAT3. To define the downstream mediator(s) of leptin's effects on autophagy, we determined the role of the master energy sensor AMP-activated protein kinase (AMPK). Leptin treatment significantly increased the phosphorylated levels of AMPKα1/2 at Thr172 site in chicken hypothalamus and liver, but not in muscle. Likewise, AMPKα1/2 was activated by leptin in chicken hypothalamic organotypic culture and Sim-CEL, but not in QM7 cells. Blocking AMPK activity by compound C reverses the autophagy-inducing effect of leptin. Together, these findings indicate that AMPK mediates the effect of leptin on chicken autophagy in a tissue-specific manner.

Roe-derived phospholipid administration enhances lymphatic docosahexaenoic acid-containing phospholipid absorption in unanesthetized rats.

Plasma n-3 fatty acids are important as the supplying pool of n-3 fatty acids to various tissues including the brain, although the relationship between dietary n-3 fatty acids and their molecular species in the plasma are not fully clarified. We investigated the intestinal absorption of docosahexaenoic acid (DHA) derived from fish roe phospholipid (Roe-PL) and compared it with fish oil triacylglycerol and free DHA using unanesthetized lymph-cannulated rats. The DHA absorption from intraduodenally administered three samples were not significantly different, whereas Roe-PL administration resulted in a significantly higher level of DHA in the phospholipid fraction than the other two samples administrations. DHA in Roe-PL at the sn-2 position was less hydrolyzed by pancreatin than by purified phospholipase A2 in vitro and simultaneous administration of free DHA and lysophosphatidylcholine did not produce the same results as the Roe-PL administration. Our results indicate that dietary DHA-containing phospholipid is effective to increase the systemic DHA incorporated into phospholipids via intestinal absorption and biosynthesis.

The delaying effect of alpha-glycerophosphocholine on senescence, transthyretin deposition, and osteoarthritis in senescence-accelerated mouse prone 8 mice.

Administration of alpha-glycerophosphocholine (GPC), a choline compound in food, is expected to contribute to human health. In this study, we evaluated its effect on aging in senescence-accelerated mouse prone 8 (SAMP8) mice. Male SAMP8 mice had free access to a commercial stock diet and drinking water with or without GPC (0.07 mg/ml). Mice in the GPC group had significantly lower total senescence grading score than that of the control group at 36 weeks of age. Administration of GPC decreased the deposition of transthyretin (TTR), an amyloidogenic protein, in the brain. Aggregated TTR activated microglia and led to neuroinflammation. Thus, GPC would protect the brain by reducing TTR deposition and preventing neuroinflammation. In a histological study of knee joints, it was found that SAMP8 mice administered GPC showed decreased joint degeneration. These results suggest that GPC delays the aging process and may be a useful compound in anti-aging functional food development.

Gene expression profiling in embryonic chicken ovary during asymmetric development.

The reproductive system in female birds arises as bilateral asymmetrical anlagen, excluding the birds of prey. Earlier, histological and messenger RNA (mRNA) expression profile studies of several genes related to gonadal sex differentiation in chicken embryos tried to elucidate the query of this asymmetry in a scattered manner. To understand the matter precisely, we have focused on mRNA expression of a cohort of genes (FSHR, CYP19A1, caspase 3, caspase 8) in second half of the embryonic days (E10-E18). The established role of leptin in development of the embryo and its expression in the embryonic ovary also drove us to check leptin receptor (LEPR) expression in the ovary. Increased expression of FSHR and CYP19A1 in the left ovary compared with that in the right ovary was identified (P < 0.05), promoting preferential left ovarian development and functionality. Significant high expression (P < 0.05) of the apoptotic genes in the right ovary were also involved here. Leptin probably has no direct influence on ovarian asymmetry as no significant variation in gonadal mRNA expression of LEPR was observed within the same experimental days. We propose that asymmetric expression of this cohort of genes (FSHR, CYP19A1, caspase 3, caspase 8) leads to the development of dimorphic gonads during embryogenesis.

Neuroendocrine Control of Broodiness.

In the majority of vertebrates, survival of offspring to sexual maturation is important for increasing population size, and parental investment in the young is important for reproductive success. Consequently, parental care is critical for the survival of offspring in many species, and many vertebrates have adapted this behavior to their social and ecological environments. Parental care is defined as any behavior that is performed in association with one's offspring (Rosenblatt, Mayer, Siegel. Maternal behavior among nonprimate mammals. In: Adler, Pfaff, Goy, editors. Handbook of behavioral neurobiology. New York: Plenum; 1985. p. 229-98) and is well characterized in mammals and birds. In birds (class Aves), this is due to the high level of diversity across species. Parental behavior in birds protects the young from intruders, and generally involves nest building, incubation, and broody behavior which protect their young from an intruder, and the offspring are reared to independence. Broodiness is complexly regulated by the central nervous system and is associated with multiple hormones and neurotransmitters produced by the hypothalamus and pituitary gland. The mechanism of this behavior has been extensively characterized in domestic chicken (Gallus domesticus), turkey (Meleagris gallopavo), and pigeons and doves (family Columbidae). This chapter summarizes broodiness in birds from a physiology, genetics, and molecular biology perspective.

Leptin activates chicken growth hormone promoter without chicken STAT3 in vitro.

Leptin is an adipocyte-derived hormone that not only regulates food intake and energy homeostasis but also induces growth hormone (GH) mRNA expression and release, thereby controlling growth and metabolism in mammals. The molecular mechanism of leptin-induced regulation of GH gene transcription is unclear. The current study investigated the effects of leptin on the chicken GH (cGH) promoter and the molecular mechanism underlying leptin-induced cGH gene expression in vitro. Leptin activated the cGH promoter in the presence of chPit-1α in CHO cells stably expressing the chicken leptin receptor. Promoter activation did not require STAT-binding elements in the cGH promoter or STAT3 activity. However, JAK2 activation was required for leptin-dependent activity. JAK2-dependent pathways include p42/44 MAPK and PI3K, and inhibition of these pathways partially blocked leptin-induced cGH gene transcription. Although CK2 directly activates JAK2, a CK2 inhibitor blocked leptin-dependent activation of the cGH gene without affecting JAK2 phosphorylation. The CK2 inhibitor suppressed Erk1/2 and Akt phosphorylation. Additional data implicate Src family kinases in leptin-dependent cGH gene activation. These results suggest that leptin activates the cGH gene in the presence of chPit-1α via several leptin-activated kinases. Although further study is required, we suggest that the leptin-induced JAK2/p42/44 MAPK and JAK2/PI3K cascades are activated by Src-meditated CK2, leading to CBP phosphorylation and interaction with chPit-1α, resulting in transactivation of the cGH promoter.