Insulin-like Growth factor-I mRNA Levels Research Articles

Effects of age and seasonal temperatures on cortisol levels and GHR, IGF-I, and IGF-II expressions in rainbow trout (Oncorhynchus mykiss)

The growth hormone (GH)/insulin-like growth factor (IGF) endocrine axis regulates the cellular growth and organ development in related to changing environmental conditions and age. The aim of this study is to determine growth factor genes, which are biological markers of growth in muscle and liver of rainbow trout (Oncorhynchus mykiss) in different seasonal temperatures and age ranges and the reveal of the relationship between serum cortisol (COR) levels from stress parameters. No difference was found in serum COR levels between the groups with respect to temperature and age. Serum GH levels were found to be higher in the summer juvenile trout compared to the winter juvenile and adult trouts. There was no difference in liver growth hormone receptor (GHR) mRNA levels of juvenile and adult trouts in winter while insulin-like growth factor-I (IGF-I) and insulin-like growth factor-II (IGF-II) mRNA levels in liver and muscle tissues were found to be higher in juvenile trout compared to adults. Among trout of different ages, GHR, IGF-I and IGF-II mRNA levels in liver in summer were higher for juvenile trout compared to adults. Muscle IGF-I mRNA levels in summer were higher in adult trout compared to juveniles. IGF-II mRNA levels in liver and muscle tissues of juvenile trout showed an increase in winter compared to in summer. While the GHR and IGF-II mRNA levels in the liver tissue of adult trout were observed to higher in winter compared to summer, IGF-I mRNA levels were found to be higher in summer. GHR, IGF-I and IGF-II mRNA levels in muscle tissue of adult trout were found to be higher in summer than in winter. This study indicated that juvenile and adult rainbow trout (Oncorhynchus mykiss) are adapted to both winter and summer temperature and that GHR, IGF-I and IGF-II genes are highly expressed.

Growth and Hepatic Insulin-Like Growth Factor-I Gene Expression in Dominant and Subordinate Oreochromis Niloticus L Under Limited Period of Physical Interaction

Social stress is known to regulate several aspects of the teleost physiology. This study explored the influence of limited period of physical interaction on growth and hepatic insulin-like growth factor-I (IGF-I) messenger RNA (mRNA) expression of the fish. Twenty all-male Oreochromis niloticus were isolated for 10 days and were used in a social pair study. After the social interaction was settled, dominant and subordinate individuals in a pair were reared separately in one aquarium separated by glass divider. The fish were fed at the same rate daily to remove the possible effect of nutrition. The glass divider was removed 10 min daily for social interaction. Weight was monitored on Days 2, 7 and 14 during the experimental period, then hepatic IGF-I mRNA expression was quantified. During the 14 days social experiment, mean specific growth rate of dominant fish (1.6%·day−1) was significantly higher (P<0.01) than that of the subordinate fish (0.9%·day−1). Dominant fish also had 2.5 fold significantly higher (P<0.05) mean IGF-I mRNA expression than that of subordinate fish. These indicate that even under limited period of physical contact but with period of visual communication, social status regulates growth and hepatic IGF-I gene expression in this species of fish. There was also a significant positive correlation (r = 0.52; P<0.01) between growth and IGF-I mRNA level which supports the previous studies that hepatic IGF-I gene expression has a potential utility as an instantaneous growth rate indicator for O. niloticus.

Association of growth hormone and insulin-like growth factor I genotype with body weight, dominance of body weight, and mRNA expression in Korat slow-growing chickens.

ObjectiveGrowth hormone (GH) and insulin-like growth factor I (IGF-I) play a critical role in animal growth rates. We aimed to investigate the effect of GH and IGF-I genotypes on body weight (BW), dominance, and gene expression in slow-growing chickens at different ages.MethodsA total of 613 Korat chickens (KRs) were bred and divided into three groups by genotype – A1A1, A1A3, and A3A3 for GH and AA, AC, and CC for IGF-I. Chickens were weighed every two weeks, and liver and breast muscle tissues were collected at 10 weeks of age. Genetic parameters of KRs were estimated using ASReml software. The GH and IGF-I mRNA levels were measured by quantitative polymerase chain reaction. Significant differences between traits were analyzed using the generalized linear model.ResultsA significant effect of GH genotypes on BW was found at most ages, and the A1A1 genotype had the highest value of BW. Compared with the A3A3 genotype, the A1A1 and A1A3 genotypes showed a higher dominance effect at 0 and 2 weeks, and genotype A1A1 had the highest value of dominance at 8 weeks of age. A difference in GH mRNA levels between genotypes was detected in breast muscle at 6 weeks and in the liver tissue at 2 weeks. In the case of IGF-I gene, the AA genotype had the highest BW at the beginning of life. Significant differences in BW dominance were found at 2 weeks. However, IGF-I mRNA levels were not different among genotypes in both breast muscles and liver tissues.ConclusionOur results revealed that GH and IGF-I influence growth, but may not be involved in heterosis. GH can be used as a marker gene in selection programs for growth because the homozygous genotype (A1A1) had the highest BW at all ages. The IGF-I is not a useful marker gene for selection programs.

Effects of TGF-β1 on the expression of endometrial stromal cell-related protein and mRNA.

To investigate the effects of transforming growth factor β1 (TGF-β1) on α-smooth muscle actin (α-SMA), insulin-like growth factor I (IGF-I), and type I collagen (Col I) expression in endometrial stromal cells as well as on fibronectin (FN) level. 56 patients with normal endometrial tissue obtained from surgery were selected from June 2018 to November 2019. Endometrial stromal cells were isolated from patients and then assigned to the control group and observation group (addition of TGF-β1) followed by the analysis of cellular activity by Thiazole blue staining; and α-SMA, IGF-I, Col I, and FN mRNA and protein levels by real-time fluorescent PCR and Western blot. The cell proliferation rate at 12 h, 24 h, 36 h, and 72 h after culture in both groups was higher than 0 h (p < 0.05) with higher cell proliferation in the observation group than the control group (p < 0.05). Real-time fluorescence PCR results showed that the levels of α-SMA, IGF-I, Col I, and FN mRNA in endometrial stromal cells of the observation group after TGF-β1 intervention were higher than those in the control group (p < 0.05). Meanwhile, α-SMA, IGF-I, Col I, and FN protein level was also elevated in the observation group after TGF-β1 treatment (p < 0.05). TGF-β1 can stimulate the proliferation of endometrial stromal cells, which may be related to regulate α-SMA, IGF-I, Col I, and FN expression.

Growth, stress and non-specific immune responses of turbot (Scophthalmus maximus) larvae exposed to different light spectra

The welfare of farmed fish is an important issue in aquaculture. There is particular concern regarding ambient light in culture systems. In the current study, turbot (Scophthalmus maximus) larvae were exposed to four different light spectra: full spectrum (LDF), blue (LDB, peak at 450 nm), orange (LDO, peak at 595 nm) and red (LDR, peak at 629 nm) from the embryo stage to 60 days post hatching (dph). During this time, the growth and immune response of the turbot were evaluated. Whole fish tissue samples were collected and weighed. mRNA expression levels of insulin-like growth factor-I (IGF-I), heat shock protein 70 (HSP70), glutathione S-transferase (GST), catalase (CAT), metallothionein (MT), lysozyme (LZM), cathepsin D (CTSD), cathepsin F (CTSF) and the enzyme activity of superoxide dismutase (SOD), CAT, and peroxidase (POD) were measured at 10, 20, 30, 40, 50, and 60 dph. The results showed that LDB had a positive effect on the growth of turbot larvae at 20, 40, 50 and 60 dph, while this effect was not significant at 10 and 30 dph. Levels of IGF-I mRNA also showed a similar tendency, indicating the crucial interaction between IGF-I and somatic growth. The effect of light spectrum on the stress response of turbot larvae was stage specific. At 10 dph, prior to metamorphosis, long wavelengths could induce a stress response in turbot larvae. At 20 dph, metamorphosis began and no significant stress response was observed in larvae exposed to different light spectra; however, LDO significantly up-regulated SOD, CAT, POD and LZM activity. Metamorphosis continued until 56 dph. From 20 to 60 dph long wavelengths (LDR and LDO) resulted in a stress response characterized by high mRNA expression levels of HSP70, GST, CAT, MT, LZM, CTSD and CTSF. SOD, CAT, POD and LZM activities were inhibited, indicating increased enzyme consumption to maintain homeostasis. Overall, our results suggested that LDF should be used in turbot culture systems prior to metamorphosis and LDB should be used after metamorphosis. These findings are in keeping with the changes in light spectra experienced by turbot larvae undergoing metamorphosis in the wild.

Myostatin in black Muscovy duck (Cairina moschata): full-length cDNA cloning and age-dependent mRNA expression compared with IGF-I

Insulin-like growth factor-I (IGF-I) and myostatin (MSTN) are a pair of critical positive and negative growth regulators. The aim of the current study was to examine the age-dependent and muscle-specific expression of IGF-I and MSTN mRNAs in black Muscovy ducks in order to understand their roles in regulating the postnatal muscle growth of domestic ducks.The full-length cDNA of the black Muscovy duck MSTN gene was cloned and the age-dependent mRNA expression profile was compared with that of the IGF-I mRNA in skeletal muscles.The cDNA sequence of the MSTN gene was 1128 bp in length and encodes 375 amino acids, with more than 94.9% homology with poultry MSTN genes, and 83.0–92.0% homology with that of human and mammals (accession: KR006339.1).The IGF-I and MSTN mRNA expression exhibited opposite trends in age-dependency and in different muscles: IGF-I mRNA level was high in the early postnatal stage and low in the late mature stage, corresponding positively to growth; while the MSTN mRNA was low in the early stage, increased gradually and reached the highest level in mature muscles, and was negatively related to muscle growth. In the breast muscles, IGF-I mRNA was much higher than in the leg muscles; the opposite effect was seen in MSTN mRNA.These data suggest that the relative expression levels of IGF-I and MSTN are essential determinants in the temporal and muscle-specific regulation of postnatal skeletal muscle growth in Muscovy duck and possibly in other poultry species as well.

IGF-I stimulates ERβ and aromatase expression via IGF1R/PI3K/AKT-mediated transcriptional activation in endometriosis.

Estrogen receptor beta (ERβ, encoded by ESR2 gene) and cytochrome P450 aromatase (encoded by CYP19A1 gene) play critical roles in endometriosis, and the levels of insulin-like growth factor-I (IGF-I) in the peritoneal fluid are significantly higher in patients with endometriosis compared with those in normal women. However, the effects and mechanisms of IGF-I on ERβ and aromatase expression remain to be fully elucidated. In this study, human endometriotic stromal cells (ESCs) and endometrial cells (EMs) derived from ovarian endometriomas and eutopic endometrial tissues. ESCs were cultured with IGF-I, signal pathway inhibitors, and siRNAs. ERβ and aromatase expression were measured by real-time PCR and Western, respectively. The binding of c-Jun and CREB to the ESR2 and CYP19A1 promoters was assessed by chromatin immunoprecipitation assay. Animal experiments were performed in a xenograft mouse model. Levels of IGF-I mRNA in ESCs were markedly higher than those in EMs. IGF-I upregulated ERβ and aromatase expression in ESCs after stimulation of the IGF1R/PI3K/AKT pathway. Following IGF-I treatment, a marked increase in c-Jun and CREB phosphorylation occurred, enhancing binding to the ESR2 and CYP19A1 promoters. An IGF1R inhibitor in vivo reduced IGF-I-induced endometriosis graft growth and ERβ and aromatase expression. In conclusion, this is the first report to describe a mechanistic analysis of ERβ and aromatase expression regulated by IGF-I in ESCs. Moreover, an IGF1R inhibitor impeded ectopic lesion growth in nude mice. These findings suggest that an inhibitor of IGF1R might have therapeutic potential as an antiendometriotic drug. Level of IGF-I mRNA in ESCs is markedly higher than that in EMs. IGF-I up-regulates ERβ and aromatase expression via IGF1R/PI3K/AKT pathway. C-Jun and CREB are recruited to ESR2 or CYP19A1 promoter by IGF-I stimulation. IGF-1R inhibitors in vivo impede the growth of ectopic lesions in nude mice.

The relative expression levels of insulin-like growth factor 1 and myostatin mRNA in the asynchronous development of skeletal muscle in ducks during early development

Genetic selection is a powerful tool for modifying poultry muscle yield. Insulin-like growth factor I (IGF-I) and myostatin (MSTN) are important regulators of muscle growth, especially in the myogenesis stage. This study compared the developmental pattern of the pectoralis major (PM) and lateral gastrocnemius (LM) muscles, mRNA expression characterization of IGF-I and MSTN-A and their correlation between 14days in ovo and 1week post-hatch in two Chinese local duck breeds. During early development, the growth of duck PM and LM followed an asynchronous pattern. Variations in PM growth rate observed with development followed the relative variations of MSTN and IGF-I expression; however, the same behavior was not observed in LM. Moreover, the profile of IGF-I expression in duck skeletal muscles indicated that genetic selection for high meat-yield poultry has altered the temporal expression of IGF-I and affected cellular characteristics and mass by hatch in a PM-specific manner. The MSTN-A expression profile showed synchronization with the growth of skeletal muscle and peaks of myofiber proliferation. The expression patterns of IGF-I and MSTN suggest that duck pectoralis fibers are prioritized for proliferation in embryogenesis. The IGF-1/MSTN-A mRNA ratios in PM and LM presented very similar trends in the changes of myofiber characteristics, and differences in the IGF-1/MSTN-A mRNA ratio in PM between the two breeds corresponded to the timing of differences in PM mass between the varieties. Our results support the hypothesis that relative levels of IGF-I and MSTN mRNA may participate in ordering muscle growth rates with selected development.

GH, IGF-I and GH receptors mRNA expression in response to growth impairment following a food deprivation period in individually housed cichlid fish Cichlasoma dimerus.

Cichlasoma dimerus is a social cichlid fish capable of growing at high rates under laboratory conditions, but knowledge on somatic growth regulation is still unclear. Growth hormone (GH)/insulin-like growth factor I (IGF-I) axis is the key regulator of somatic growth in vertebrates. Two types of growth hormone receptors have been described in teleost fish, named GH receptor type 1 (GHR1) and type 2 (GHR2). In addition, isoforms of these receptors lacking part of the intracellular region have been described. The aim of this study was to evaluate the somatic growth, liver histology and changes in the GH/IGF-I axis after 4 weeks of food deprivation in C. dimerus. Four-week fasted fish showed reductions in specific growth rates in body weight (p < 0.001) and standard length (p < 0.001). Additionally, the hepatosomatic index (p < 0.001) and hepatocyte area (p < 0.001) decreased in fasted fish, while no changes in glucose levels were detected in plasma. The starvation protocol failed to induce changes in GH mRNA levels in the pituitary and IGF-I mRNA levels in liver. In contrast, IGF-I mRNA levels in muscle decreased in fasted fish (p = 0.002). On the other hand, GHR2 (detected with primer sets designed over the extracellular and intracellular region) was upregulated by starvation both in liver and muscle (p < 0.05), while GHR1 remained unchanged. These results show that a fasting period reduced somatic growth both in length and body weight concomitantly with alterations on liver and muscle GHR2 and muscle IGF-I mRNA expression.

Increased mRNA levels of apolipoprotein M and apolipoprotein AI in the placental tissues with fetal macrosomia.

The present study examined mRNA levels of apolipoprotein M (apoM) and apolipoprotein AI (apoAI) in the term placental tissues obtained from 37 women with normal birth weight neonates and from 37 women with macrosomic neonates (birth body weight ≥4,000 g), and further discussed possible clinical significance of these observations. The mRNA levels of apoM and apoAI in the placental tissues were determined by the real time RT-PCR, which demonstrated that both apoM and apoAI mRNA levels were significantly higher in the placentas from macrosomia than those from normal birth. Moreover, we analyzed the overexpressions of apoM and apoAI with the clinical data. Meanwhile we examined several known risk factors of macrosomia including the mRNA levels of insulin-like growth factor I (IGF-I), IGF-II, insulin-like growth factor I receptor (IGF-IR) and IGF-IIR. It demonstrated that apoM expression was significantly positively correlated to the placental weight, fetal birth weight, pregestational body mass index (BMI), weight gain during pregnancy, maternal weight, maternal BMI and the mRNA levels of IGF-IR as well as IGF-IIR. The apoAI mRNA level was statistically significantly correlated to the placental weight, fetal birth weight, IGF-I and IGF-IR mRNA levels. Binary logistic regression analysis suggested that both apoM and apoAI mRNA may considered as independent risk factors for macrosomia. The clinical significance needs further investigation.

Effect of KH-BaRoKer-SeongJangTang based on traditional medicine theory on longitudinal bone growth

KH-BaRoKer-SeongJangTang (KBS) is a recently developed formulation by using traditional drugs considering traditional medical theory of Oriental books such as ShinNongBonChoGyeong and JuRye, which has been used to improve the growth of child in Korea. Although KBS is usually prescribed to many children who are in retard for their age, its pharmacological effects have not been fully understood in experimental models. The aim of this study was to evaluate the effects of KBS on bone growth. Growth plate thickness and bone parameters such as bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), connection density (Conn.D), and total porosity were analyzed by means of microcomputed tomography. Serum insulin-like growth factor-I (IGF-I) levels were measured by enzyme-linked immunosorbent assay. Hepatic IGF-I mRNA expression was analyzed by real-time polymerase chain reaction. Phosphorylation of signal transducer and activator of transcription5 (STAT5) was investigated using Western blot analysis and immunohistochemistry. The thickness of growth plate was increased by KBS. BV/TV, Tb.Th, TbN, Conn.D, and total porosity were improved by KBS. Hepatic IGF-I mRNA and serum IGF-I levels were elevated by KBS. Phosphorylation of STAT5 was increased with administration of KBS. These results suggest that KBS would be helpful to children who are in retard for their age through the elevation of IGF-I.

Expression profiles of growth hormone receptor and insulin-like growth factor I in cattle and yak tissues revealed by quantitative real-time PCR

Abstract. The goals of this study were to compare the mRNA expression profiles of growth hormone recep tor (GHR) and insulin-like growth factor I (IGF-I) in various tissues of cattle and the semi-wild yak (Datong yak) and to find out whether the mRNA levels of the two genes are correlated. The mRNA levels of GHR and IGF-I in heart, lung, liver, spleen, pancreas, kidney, muscle, mammary gland and ovary of cattle and yak were investigated by using quantitative real-time po ly mer ase chain reaction (PCR). The experiments showed that the transcript levels of the two genes were signif icantly higher in liver (P&lt;0.05) than in the other tissues for both species and that IGF-I levels varied more among tissues (P&lt;0.01) than did GHR levels. The GHR tran script level in pancreas was higher in yak (P&lt;0.05) than in cattle. There was no statistically sig nif i cant difference in IGF-I tran script levels among all the tissues of both bovine groups. Growth hormone receptor and IGF-I transcript levels were positively correlated in mammary gland (P&lt;0.01), lung (P&lt;0.05) and muscle (P&lt;0.05) in yak, negatively correlated in cattle heart (P&lt;0.05) and not correlated in the other tissues. The results indicate that the two genes are reg u lated differently in various tissues under normal physiological conditions in these two bovine species.

Dietary methionine effects on IGF-I and GHR mRNA expression in broilers

This study aimed to evaluate liver and breast muscle insulin-like growth factor I (IGF-I) and growth hormone receptor (GHR) gene expression between broilers fed different methionine levels and sources. Broiler chicks were 22 to 42 days old, distributed in 5 treatments (control diet, DL1 - 0.08% DL-methionine, DL2 - 0.24% DL-methionine, MHA-FA1 - 0.11% methionine hydroxy analogue-free acid, and MHA-FA2 - 0.33% methionine hydroxy analogue-free acid). The broilers were euthanized by cervical dislocation. RNA was extracted from liver and breast muscle, followed by cDNA synthesis and amplification using qRT-PCR. DL2 methionine supplementation provided best animal performance results. GHR and IGF-I gene expression in the muscle tissue was not affected by methionine supplementation. IGF-I gene expression in the liver was higher in animals fed methionine supplementation than in animals fed control diet. IGF-I mRNA levels in broilers fed DL2 were greater than DL1 (1.56 vs 0.97 AU) and greater than MAH-FA1 and MAH-FA2. Broilers fed DL2 increased significantly GHR gene expression in the liver than animals fed the control diet. Addition of methionine improved animal performance by stimulating synthesis and release of growth factor.

Divergence between hepatic insulin-like growth factor (IGF)-I mRNA expression and IGF-I serum levels in Leishmania (Leishmania) infantum chagasi-infected dogs

Visceral leishmaniasis (VL) caused in the New World by Leishmania (Leishmania) infantum chagasi has dog as important peridomestic reservoir in its transmission cycle. Since VL in infected animals is similar to human VL, its study is interesting for human pathology. During Leishmania infection, insulin-like growth factor-I (IGF-I) plays a role in the host-parasite interaction, favoring parasite growth, particularly acting directly on Leishmania. We evaluated IGF-I mRNA expression in different organs/tissues, which was differently modulated in dogs naturally infected by L. (L.) infantum chagasi. We also evaluated the hepatic IGF-I mRNA and serum IGF-I levels in infected dogs. Hepatic mRNA IGF-I expression was higher in the infected dogs than in control animals. However, the serum levels of IGF-I, which are related to the production of this factor in the liver, were reduced in the infected dogs compared with the non-infected controls. Thus, we suggest interference in post-transcriptional processing in IGF-I production in active visceral leishmaniasis.

Myogenin, MyoD and IGF-I Regulate Muscle Mass but not Fiber-type Conversion during Resistance Training in Rats

The purpose of this study was to test the hypothesis that skeletal muscle adaptations induced by long-term resistance training (RT) are associated with increased myogenic regulatory factors (MRF) and insulin-like growth factor-I (IGF-I) mRNA expression in rats skeletal muscle. Male Wistar rats were divided into 4 groups: 8-week control (C8), 8-week trained (T8), 12-week control (C12) and 12-week trained (T12). Trained rats were submitted to a progressive RT program (4 sets of 10-12 repetitions at 65-75% of the 1RM, 3 day/week), using a squat-training apparatus with electric stimulation. Muscle hypertrophy was determined by measurement of muscle fiber cross-sectional area (CSA) of the muscle fibers, and myogenin, MyoD and IGF-I mRNA expression were measured by RT-qPCR. A hypertrophic stabilization occurred between 8 and 12 weeks of RT (control-relative % area increase, T8: 29% vs. T12: 35%; p>0.05) and was accompanied by the stabilization of myogenin (control-relative % increase, T8: 44.8% vs. T12: 37.7%, p>0.05) and MyoD (control-relative % increase, T8: 22.9% vs. T12: 22.3%, p>0.05) mRNA expression and the return of IGF-I mRNA levels to the baseline (control-relative % increase, T8: 30.1% vs. T12: 1.5%, p<0.05). Moreover, there were significant positive correlations between the muscle fiber CSA and mRNA expression for MyoD (r=0.85, p=0.0001), myogenin (r=0.87, p=0.0001), and IGF-I (r=0.88, p=0.0001). The significant (p<0.05) increase in myogenin, MyoD and IGF-I mRNA expression after 8 weeks was not associated with changes in the fiber-type frequency. In addition, there was a type IIX/D-to-IIA fiber conversion at 12 weeks, even with the stabilization of MyoD and myogenin expression and the return of IGF-I levels to baseline. These results indicate a possible interaction between MRFs and IGF-I in the control of muscle hypertrophy during long-term RT and suggest that these factors are involved more in the regulation of muscle mass than in fiber-type conversion.

Developmental changes of &amp;lt;i&amp;gt;GHR&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;IGF-I&amp;lt;/i&amp;gt; mRNA expression in lamb rumen

Abstract. Lambs from birth (0-day-old) to 56-day-old were selected in present study to investigate developmental changes of growth hormone receptor (GHR) and insulin-like growth factor I (IGF-I) mRNA expression in their rumen tissue. Forty-five lambs (5 lambs per group) were slaughtered at 0, 7, 14, 21, 28, 35, 42, 49, 56 days of age respectively for sampling the tissue of the rumen dorsal sac. The abundance of GHR and IGF-I mRNA were detected through real-time quantitative PCR method. The results indicated that the expression levels of GHR and IGF-I mRNA had similar change tendency in rumen tissue that the GHR and IGF-I mRNA abundance decreased with age from birth to 56-day-old. There was significant positive correlation between the two gene mRNA expression levels. The results suggested that GHR and IGF-I gene expression levels had the specific developmental pattern in rumen tissue.

Growth and IGF-I response of juvenile Nile tilapia (Oreochromis niloticus) to changes in water temperature and dietary protein level

Water temperature and dietary protein level play an important role in influencing the growth and insulin-like growth factor I (IGF-I) in Nile tilapia juveniles. The combined effect of temperature (20–34°C) and dietary protein level (25–50%) on the specific growth rate (SGR), feed efficiency (FE), serum IGF-I level and hepatic IGF-I mRNA level was examined under laboratory conditions by employing central composite design and response surface method. Results showed that the linear effects of temperature and dietary protein level on the SGR, FE, serum IGF-I and hepatic IGF-I mRNA level were significant (P<0.05); the quadratic effects of temperature and dietary protein level on the FE and serum IGF-I were significant (P<0.05). The interaction of temperature and dietary protein level on the FE, serum IGF-I and hepatic IGF-I mRNA level all proved significant (P<0.05). The optimal temperature/dietary protein level combination was determined, i.e., 29.9°C/40.3%, at which the greatest SGR (2.748%/d) and FE (0.775) were simultaneously arrived. Both SGR and FE were linearly correlated with serum IGF-I or hepatic IGF-I mRNA level. These results suggested that optimum combination of temperature and dietary protein level would enhance tilapia growth efficiency and IGF-I would regulate growth and FE.

Growth cartilage expression of growth hormone/insulin-like growth factor I axis in spontaneous and growth hormone induced catch-up growth

IntroductionCatch-up growth following the cessation of a growth inhibiting cause occurs in humans and animals. Although its underlying regulatory mechanisms are not well understood, current hypothesis confer an increasing importance to local factors intrinsic to the long bones' growth plate (GP). AimThe present study was designed to analyze the growth-hormone (GH)-insulin-like growth factor I (IGF-I) axis in the epiphyseal cartilage of young rats exhibiting catch-up growth as well as to evaluate the effect of GH treatment on this process. Material and methodsFemale Sprague–Dawley rats were randomly grouped: controls (group C), 50% diet restriction for 3days+refeeding (group CR); 50% diet restriction for 3days+refeeding & GH treatment (group CRGH). Analysis of GH receptor (GHR), IGF-I, IGF-I receptor (IGF-IR) and IGF binding protein 5 (IGFBP5) expressions by real-time PCR was performed in tibial growth plates extracted at the time of catch-up growth, identified by osseous front advance greater than that of C animals. ResultsIn the absence of GH treatment, catch-up growth was associated with increased IGF-I and IGFBP5 mRNA levels, without changes in GHR or IGF-IR. GH treatment maintained the overexpression of IGF-I mRNA and induced an important increase in IGF-IR expression. ConclusionsCatch-up growth that happens after diet restriction might be related with a dual stimulating local effect of IGF-I in growth plate resulting from overexpression and increased bioavailability of IGF-I. GH treatment further enhanced expression of IGF-IR which likely resulted in a potentiation of local IGF-I actions. These findings point out to an important role of growth cartilage GH/IGF-I axis regulation in a rat model of catch-up growth.

The changes in growth, serum biochemical indices and GH/IGF- Ⅰ/IN mRNA expression abundance ofOreochromis niloticusduring fasting and re-feeding

Studies were conducted to reveal the changes in growth, serum biochemical indices and growth hormone (GH), insulin-like growth factor Ⅰ(IGF-Ⅰ) and insulin (IN) mRNA expression abundance of Nile tilapia (Oreochromis niloticus) during fasting and re-feeding. Nile tilapia with initial body weight (62.50 ± 3.44) g were starved for 28 d and then fed for 21 d under controllable indoor environment. Fish were sam-pled at 0, 7, 14, 21 and 28 d during fasting and at 14 and 21 d during re-feeding, respectively. The results indicated that the body weight was significantly decreased when fasting over 7 d (P0.05), and signifi-cantly increased when re-feeding for 21 d (P0.05). The hepatosomatic index was significantly decreased throughout the experiment (P0.05). Significant reduction was observed in the content of triglyceride and glucose, and in the activities of alkaline phosphatase, glutamic oxaloacetic transaminase and glutamic py-ruvic transaminase after fasting (P0.05); After re-feeding, the value of these indices increased in varying degrees, but the activity of transaminase was significantly lower than initial value(P0.05). There was no change in total cholesterol, high density lipoprotein cholesterol or low density lipoprotein cholesterol dur-ing the experiment (P0.05). Serum GH and liver GH mRNA levels showed significantly up-regulation, whereas significant down-regulation was observed in serum IGF-Ⅰ and liver IGF-Ⅰ mRNA levels after fasting, and after re-feeding both of them increased (P0.05). IN mRNA level was significantly increased during fasting for 7-21 d (P0.05), but its level was not obviously changed when fasting for 28 d (P0.05), then was significantly decreased after re-feeding (P0.05). The present study revealed that fasting could restrain the growth of O. niloticus, promote serum triglyceride and glucose breakdown, and decrease the activity of transaminase. Serum GH/IGF-Ⅰ and liver GH/IGF-Ⅰ mRNA expression abundance displayed synchronous changes and the liver IN mRNA expression abundance was significantly increased when fasting for 7-21 d and then decreased to normal level when fasting for 28 d. It suggests that the level of GH/IGF-Ⅰ gene transcription of O. niloticus may be the most important factor in determining the levels of hormone in serum, while down-regulation of serum insulin may be due to its release reduction in islet when fasting.

Prenatal stress induces long-term effects in cell turnover in the hippocampus-hypothalamus-pituitary axis in adult male rats.

Subchronic gestational stress leads to permanent modifications in the hippocampus-hypothalamus-pituitary-adrenal axis of offspring probably due to the increase in circulating glucocorticoids known to affect prenatal programming. The aim of this study was to investigate whether cell turnover is affected in the hippocampus-hypothalamus-pituitary axis by subchronic prenatal stress and the intracellular mechanisms involved. Restraint stress was performed in pregnant rats during the last week of gestation (45 minutes; 3 times/day). Only male offspring were used for this study and were sacrificed at 6 months of age. In prenatally stressed adults a decrease in markers of cell death and proliferation was observed in the hippocampus, hypothalamus and pituitary. This was associated with an increase in insulin-like growth factor-I mRNA levels, phosphorylation of CREB and calpastatin levels and inhibition of calpain -2 and caspase -8 activation. Levels of the anti-apoptotic protein Bcl-2 were increased and levels of the pro-apoptotic factor p53 were reduced. In conclusion, prenatal restraint stress induces a long-term decrease in cell turnover in the hippocampus-hypothalamus-pituitary axis that might be at least partly mediated by an autocrine-paracrine IGF-I effect. These changes could condition the response of this axis to future physiological and pathophysiological situations.