Diurnal Changes in Blood Metabolites and Their Relation to Plasma Growth Hormone and Time of Feeding in Mithun Heifers (Bos frontalis)

The aim of the present study was to investigate what, if any, diurnal changes occur in blood metabolites in relation to plasma growth hormone (GH) and feeding time among mithun (Bos frontalis), a semi‐wild ruminant. Blood samples were collected at hourly intervals during a 24 h span from 6 mithun heifers (averaging 2.5 yr of age and averaging 230 kg in weight) that were fed twice a day at 11:00 and 16:00 h. Samples were assayed for plasma GH and blood metabolites, non‐esterified fatty acids (NEFA), glucose, and alpha‐amino nitrogen. The total sampling period was divided into a 1) postprandial (after meal) period (period I: 11:00 to 21:00 h) and 2) interprandial period (period II: 22:00 to 10:00 h) and also into night (20:00 to 05:00 h) and day (06:00 to 10:00 h) periods for statistical analysis. Plasma glucose and alpha‐amino nitrogen levels increased (p<0.01), and plasma NEFA and GH decreased (p<0.01) after each meal. No diurnal rhythmicity was detected in plasma glucose or alpha‐amino nitrogen levels. Interestingly, plasma NEFA and GH levels were higher (p<0.01) during the interprandial (period II) and night periods, indicating an energy deficit that occurred progressively during the interprandial period of nocturnal feed deprivation. In twice‐daily‐fed mithuns we conclude that: 1) plasma metabolites and GH exhibited a definite pattern of change with time of feeding; 2) concentrations of plasma NEFA were higher nocturnally due to an energy deficit and that GH levels were higher during the interprandial period after the second meal; 3) the interprandial period after the second feeding may be considered to constitute a short‐term food deprivation; 4) the longer interprandial period of 19 h in this study between the second and subsequent morning meal may be changed into equally divided feedings to minimize the short‐term energy deficit; and 5) blood sampling for blood metabolites in mithuns should be conducted at a fixed time of day with special emphasis on time of feeding.     

Secretion patterns of growth hormone in growing captive mithuns (Bos frontalis)

A study was conducted in May 2003 to characterize plasma growth hormone (GH) pattern in growing mithuns (Bos frontalis), a rare semi-wild ruminant. Six mithun calves averaging 235 day of age and 124 kg were maintained in semi-intensive system and group-fed once daily. Animals gained at a mean rate of 0.54 kg/day, with individuals ranging from 0.34 to 0.66 kg/day. Blood samples collected at 15-minute intervals starting from 0600h for nine-hour period were assayed for plasma GH. Growth hormone patterns consisted of frequent pulses of varying amplitude. Growth hormone pulses occurred at an average frequency of 0.69/h, the rate did not differ markedly among mithuns nor hour of day. The magnitude of GH secretory pulses varied significantly among mithuns. Growth hormone peaks averaged 95.0 and 45.2 ng/ml in mithuns having the highest and lowest GH peaks, respectively. Peak and mean GH levels were associated positively (r=0.98, P<0.001) and both were associated negatively (r=-0.97 and -0.98, respectively; P<0.01) with rates of gain. Results from the study show that 1) GH peaks occur at frequent intervals throughout the sampling period and 2) alteration in GH levels and patterns are elicited more by pulse amplitude than frequency modulation.     

Infradian rhythmicity in lactogenic hormone (prolactin,growth hormone,cortisol and thyroid hormone) secretion throughout the lactation cycle in mithun cows (Bos frontalis): variation among strains

The role of lactogenic hormones (prolactin, growth hormone, cortisol and thyroid hormone) on lactation yield in Mithun cows as well as their rhythmicity throughout the lactation cycle were studied in Mizoram (n = 4) and Nagaland (n = 7) strain of mithun (Bos frontalis). Blood samples were collected from all the animals from the day of calving to the complete dry off at an interval of 15 days. All the hormones were estimated in the serum by commercially available ELISA kits. Plasma level of cortisol (μg/dl), growth hormone (GH, in ng/ml), prolactin (PRL, in μIU/ml), triiodothyronine (T₃, in nmol/μl) and thyroxin (T₄, in ng/ml) were 20.84 ± 0.29, 28.08 ± 0.56, 9.87 ± 0.20, 27.82 ± 0.56 and 51.33 ± 0.48, respectively, in mithun irrespective of strains during the lactation period. Levels of all the hormones varied significantly (p ≤ 0.01) during different days of lactation cycle but, there was no significant difference among strain. Levels of PRL, GH, cortisol and T₃ were significantly (p < 0.01) higher around calving and declined sharply. The hormones remained in almost steady state during mid-lactation and declined during late lactation. All the hormones stated above were positively correlated with lactational yield thus their role on lactogenesis and galactopoiesis was established.     

Secretion patterns of luteinizing hormone in growing mithuns (Bos frontalis)

To characterize the luteinizing hormone (LH) secretion patterns in growing mithun (Bos frontalis), a semi-wild ruminant, six female mithuns (1 year old; BW: 145.5 kg) were maintained in a semi-intensive system. Plasma progesterone (P(4)) level was measured in twice-a-week samples collected for six weeks to assess ovarian status. This was followed by a frequent sampling period. Blood samples collected at 15 min intervals for 9 h were assayed for plasma LH. Luteinizing hormone patterns consisted of pulses of varying amplitudes. Luteinizing hormone pulses occurred at an average rate of 0.54/h ( approximately 5 pulses/9 h). The rate did not differ among mithuns. The mean plasma LH levels was correlated with body weight (r=0.82; p<0.05) and pulse amplitude (r=0.87; p<0.01). Neither the LH amplitude nor the frequency was affected by time (p>0.05). The mean plasma P(4) concentration was 0.37 ng/ml. In conclusion, we demonstrated a pulsatile nature of LH secretion in growing mithuns. In addition, the mean plasma LH level and LH amplitude were positively correlated with body weight. It appears that in contrast to cattle, five LH pulses per nine hours recorded in mithuns were not an indication of approaching puberty.     

Relationship of plasma estradiol-17beta, total estrogen, and progesterone to estrus behavior in mithun (Bos frontalis) cows

The objectives of this study were (1) to establish the characteristics of estrus behavior in mithun cows (n = 12) and (2) to determine the relationships between this behavior and the plasma concentrations of estradiol-17beta (E2), total estrogen, and progesterone. Estrus was detected by visual observations of estrus signs, per recta examination of genitalia and bull parading thrice a day for three consecutive cycles. Among the behavioral signs of estrus, the cow to be mounted by bull (100%) was the best indicator of estrus followed by standing to be mounted (92%). Per rectum examination of genital organs revealed relaxed and open os externa of cervix, turgid uterus, and ovaries having palpable follicles in all animals. The mean (+/-SEM) length of estrus cycle and duration of estrus were recorded to be 21.8 +/- 0.69 days and 12.6 +/- 1.34 h, respectively. Endocrine profiles during the peri-estrus period showed that the mean highest peak concentrations of E2 (27.29 +/- 0.79 pg/ml) and total estrogen (45.69 +/- 2.32 pg/ml) occurred at -3.90 +/- 2.27 and -3.89 +/- 2.26 h prior to the onset of estrus, respectively. Plasma progesterone concentration was basal (0.14 +/- 0.001 ng/ml) during the peri-estrus period. Plasma E2 and total estrogen were found to increase from 6 days before estrus to reach a peak level on the day of estrus and decline thereafter to basal level on day 3 of the cycle. The plasma progesterone concentration was the lowest on the day of estrus showing gradual increase to register a peak level on day 15 of the cycle. Estrus behavior was found to be positively correlated with the maximum peak concentration of E2 (r = 0.89; P < 0.0001) and total estrogen (r = 0.66; P = 0.019) during the peri-estrus period. The mean total estrogen concentration during the peri-estrus period was significantly correlated with estrus behavior (r = 0.60; P = 0.04). The correlations between the estrus behavior and E2:progesterone ratios at 6 days before the onset of estrus (r = 0.92) and on the day of estrus (r = 0.95) was significant. The total estrogen:progesterone ratios at 6 days before the onset of estrus and on the day of estrus were also positively correlated with the estrus behavior (r = 0.86 and 0.88). In conclusion, our results suggest that the maximum peak concentration of E2 and total estrogen and mean level of total estrogen during the peri-estrus period and the E2:progesterone and total estrogen:progesterone ratios on 6 days before the onset of estrus and on the day of estrus are the important factors contributing the behavioral manifestation of estrus in mithun cows.     

独龙牛遗传多样性及其种群遗传结构的等位酶分析

采用水平片淀粉凝胶电泳技术,进行３０头独牛牛４１种蛋白质共计４４个遗传座位的等位酶分析,只在Ｔｒ,Ｈｐ,Ａｍｙ,Ｅｓｔ等４个座位发现多态性。每个座位等基因的平均数、多态座位百分比和平均杂合度值分别为Ａ＝１．０９０９、Ｐ＝０．０６８２和Ｈ＝０．０２６２。贡山县和福贡县独龙牛群体从酶基因的角度上看遗传多样性贫乏,可能是分别由小种群引种而来,受到瓶颈效应的作用,并伴随着创立者事件的发生。我们结合独龙牛在     

云南黄牛和大额牛的mtDNA多态性研究

本文以mtDNA限制性内切酶片段长度多态技术分析云南牛的mtDNA多态性。结果表明云南黄牛有两种类型的mtDNA分子,一种是普通黄牛类型,另一种是瘤牛类型,两者的频率分别为33%和67%。没有发现过渡型和重组型。昆明黑白花奶牛的mtDNA与云南黄牛的相类似。云南黄牛可能具有两种起源,即普通黄牛起源和瘤牛起源。今天的云南黄牛群体是这两种类型的混合。大额牛的限制性类型与瘤牛相同,表明大额牛的起源与瘤牛有密切关系。     

Growth hormone responses to growth hormone-releasing hormone (1-29)-NH2 and a D-Ala2 analog in normal men

Synthetic analogs of growth hormone-releasing hormone, GHRH(1-29)-NH2 and D-Ala2 GHRH(1-29)-NH2 were administered as a bolus intravenous injection to five normal men in a dose range of 0.015 to 0.5 micrograms/kg body weight. Vehicle only was administered in a control study. Peak responses to GHRH analogs occurred at 15 or 30 min. An increase in the integrated plasma growth hormone (GH) response was observed at each dose. The dose-response curve of GHRH(1-29)-NH2 indicated that it has a similar molar potency to GHRH(1-40) and GHRH(1-44). The potency of D-Ala2 GHRH(1-29)-NH2 was approximately twice that of GHRH(1-29)-NH2. Neither analog affected blood levels of PRL, TSH, LH, FSH, ACTH, insulin, glucagon, glucose, cortisol, free thyroxine, and free triiodothyronine. No side effects were noted other than transient flushing with the highest dose administered. The findings demonstrate GHRH(1-29)-NH2 and its D-Ala2 analog are potent stimulators of GH release and have potential application in clinical medicine.     

Influence of training on the response to exercise of adrenocorticotropin and growth hormone plasma concentrations in human swimmers

The aim of the present study was to evaluate the response of adrenocorticotropin ([ACTH]) and growth hormone ([GH]) concentrations to a typical aerobic swimming set during a training season. Nine top-level male endurance swimmers (age range 17–23 years) were tested during three training sessions occurring 6, 12 and 18 weeks after the beginning of the season. During each session, after a standard warm-up, the swimmers performed a training set of 15 × 200-m freestyle, with 20 s of rest between repetitions, at a predetermined individual speed. Blood samples were collected before warm-up and at the end of the training set. A few days before each session, the individual swimming velocity corresponding to the 4 mmol · l⁻¹ blood lactate concentration (v ₄) was assessed as a standard of aerobic performance. Aerobic training affected v ₄ levels, which were highest 18 weeks after the beginning of the season; at the same time, while [ACTH] response was attenuated, [GH] response was enhanced. These results could be considered as adaptations to the exercise intensity. In our training programme, these adaptations seemed to have occurred between the 12th and 18th weeks of the training season. Accepted: 21 April 1998     

Diurnal changes in blood metabolites and their relation to plasma growth hormone and time of feeding in mithun heifers (Bos frontalis)

The aim of the present study was to investigate what, if any, diurnal changes occur in blood metabolites in relation to plasma growth hormone (GH) and feeding time among mithun (Bos frontalis), a semi-wild ruminant. Blood samples were collected at hourly intervals during a 24 h span from 6 mithun heifers (averaging 2.5 yr of age and averaging 230 kg in weight) that were fed twice a day at 11:00 and 16:00 h. Samples were assayed for plasma GH and blood metabolites, non-esterified fatty acids (NEFA), glucose, and alpha-amino nitrogen. The total sampling period was divided into a 1) postprandial (after meal) period (period I: 11:00 to 21:00 h) and 2) interprandial period (period II: 22:00 to 10:00 h) and also into night (20:00 to 05:00 h) and day (06:00 to 10:00 h) periods for statistical analysis. Plasma glucose and alpha-amino nitrogen levels increased (p<0.01), and plasma NEFA and GH decreased (p<0.01) after each meal. No diurnal rhythmicity was detected in plasma glucose or alpha-amino nitrogen levels. Interestingly, plasma NEFA and GH levels were higher (p<0.01) during the interprandial (period II) and night periods, indicating an energy deficit that occurred progressively during the interprandial period of nocturnal feed deprivation. In twice-daily-fed mithuns we conclude that: 1) plasma metabolites and GH exhibited a definite pattern of change with time of feeding; 2) concentrations of plasma NEFA were higher nocturnally due to an energy deficit and that GH levels were higher during the interprandial period after the second meal; 3) the interprandial period after the second feeding may be considered to constitute a short-term food deprivation; 4) the longer interprandial period of 19 h in this study between the second and subsequent morning meal may be changed into equally divided feedings to minimize the short-term energy deficit; and 5) blood sampling for blood metabolites in mithuns should be conducted at a fixed time of day with special emphasis on time of feeding.     

Growth hormone and insulin-like growth factor I concentrations in bulls of various growth hormone genotypes

A leucine/valine substitution at amino acid position 127 was identified by the polymerase chain reaction and restriction fragment length polymorphism in the bovine growth hormone gene. Genotyping was performed in 84 AI bulls of three different breeds, in which plasma concentrations of growth hormone (GH) and insulin-like growth factor I (IGF-1) were also measured. Gene frequencies of variants L (leucine) und V (valine) were 0.80/0.20 (Black and White), 0.90/0.10 (Brown), 0.71/0.29 (Simmental). Hormone concentrations were measured during different physiological conditions (normal feeding, fasting, realimentation) in the majority of animals. Generally, genotype LL was associated with higher concentrations of GH than LV. This difference was significant in Black and White bulls (P < 0.05). In contrast, IGF-1 concentrations were higher in LV than in LL animals. This was most pronounced in mature, realimented Simmental bulls. We conclude that the various GH alleles influence the circulating concentrations of GH and IGF-1.     

Involvement of growth hormone (GH) and insulin-like growth factor (IGF) system in ovarian folliculogenesis

During the last decade, involvement of growth hormone (GH), insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) in ovarian folliculogenesis has been extensively studied. This review provides an update on the GH, IGF system and their role in ovarian follicular development. In vitro studies and knockout experiments demonstrated an important role of GH in preantral follicle growth and differentiation through their binding with GH receptors, which are located both in the oocyte and follicular somatic tissues. Furthermore, GH stimulates the development of small antral follicles to gonadotrophin-dependent stages, as well as maturation of oocytes. With regard to the IGF system, IGF-I has no effects on primordial follicle development, but both IGF-I and IGF-II stimulate growth of secondary follicles. Depending on the species studies and method used, these proteins have been detected in oocytes and/or somatic cells. In antral follicles, these IGFs stimulate granulosa cell proliferation and steroidogenesis in most mammals. The bioavailability of IGFs is regulated by a family of intrafollicular expressed IGF binding proteins (IGFBPs). Facilitation of IGF can be increased through the activity of specific IGFBP proteases, which degrade the IGF/IGFBP complex, resulting in the production of IGFBP fragments and release of attached IGF.     

Isolation, characterization, and distribution of two cDNAs encoding for growth hormone receptor in rainbow trout (Oncorhynchus mykiss)

Growth hormone (GH) plays important roles in a vast array of physiological processes, including growth, metabolism, and reproduction. In this study, cDNAs for two unique growth hormone receptor variants were cloned and sequenced from rainbow trout. The two cDNAs, one consisting of 2920 bp and the other of 2820 bp, share 87.2% identity in nucleotide sequence and 85.5% identity in deduced amino acid sequence and presumably arose through gene duplication. The cDNAs encode for putative 593- and 594-amino acid growth hormone receptors (designated GHR1 and GHR2, respectively), each containing a single transmembrane domain and other motifs characteristic of the receptor family. Both GHR1 and GHR2 mRNAs were present in all tissues examined. Trout GHR mRNAs are differentially expressed, both in terms of abundance among tissues and in terms of abundance within selected tissues. GHR1 was more abundant than GHR2 in the brain, whereas GHR2 was more abundant than GHR1 in pancreas and spleen. These findings expand our understanding of the evolution of the GH receptor family and suggest that independent mechanisms serve to regulate the tissue-specific expression of GHR mRNAs.     

Developmental correlation between hypothalamic somatostatin and hypophysial growth hormone

Summary The objective of the present study was to determine, by means of immunocytochemistry, the age in fetal development at which GH is first detectable in the pituitary gland and somatostatin in the median eminence, and to correlate temporally the development of these two hormones throughout the remainder of pregnancy. Mice were studied at 15–19 days of gestation with the peroxidase-antiperoxidase (PAP) technique of Sternberger. Somatotropes in the pars distalis were initially detected at 16 days of gestation and by 17 days they were a prominent component of the parenchymal cell population of the hypophysis. These cells were ovoid and distributed uniformly throughout the pars distalis; many were located adjacent to sinusoidal capillaries. Their number and staining intensity increased by 19 days. Somatostatin was not consistently observed in the median eminence until 19 days of gestation. Reaction product indicative of the presence of somatostatin in presumptive nerve endings was located on the ventral surface of the median eminence and in the external lamina of the infundibulum in proximity to the superficial portal capillaries. Results of the present investigation support the concept that the potential for neuroendocrine control of GH secretion exists in the mouse by the end of fetal development. Several hypotheses concerning the temporal relationship between the appearance of somatostatin in the hypothalamus and of GH in the anterior pituitary gland are discussed.Supported by a Biomedical Research Support Grant (NIH RR 5417). Appreciation is extended to the National Pituitary Agency, NIAMDD for the following radioiodination-grade hormones: hGH, rPRL, rTSH, rFSH and hCG     

(D)-2-tert-Butoxycarbonylamino-5,5-difluoro-5-phenyl-pentanoic acid: synthesis and incorporation into the growth hormone secretagogues

The first enantioselective synthesis of (d)-2-tert-butoxycarbonylamino-5,5-difluoro-5-phenyl-pentanoic acid 3 was achieved. The incorporation of the titled compound into growth hormone secretagogue (GHS) compounds resulted in new analogs 10 and 16, both of which had significantly increased in vitro potency. The compound 10 also showed improved in vivo efficacy as well as pharmacokinetic properties in rat models.     

Standardization and validation of a simple,sensitive, second antibody format enzyme immunoassay for growth hormone determination in mithun (Bos frontalis) plasma

To facilitate research into the action of growth hormone (GH) in mithun (Bos frontalis), we standardized and validated a simple and highly sensitive enzyme immunoassay (EIA) for GH determination in mithun blood plasma on microtiter plates using biotin‐streptavidin amplification system and the second antibody coating technique. Biotin was coupled to GH and used to bridge between streptavidin‐peroxidase and immobilized antiserum in competitive assay. The EIA was carried out directly in 25 µl mithun plasma. The GH standards ranging from 0.25 ng/well/25 µl to 128 ng/well/25 µl were prepared in charcoal‐treated plasma collected from an aged (>10 years) senile mithun. The sensitivity of EIA procedure was 1.0 ng/ml plasma; the 50% relative binding sensitivity was seen at 36 ng/ml plasma. Plasma volumes for the EIA, namely 12.5 and 25 µl, did not influence the shape of standard curve even though a drop in the optical density (OD)₄₅₀ observed with higher plasma volumes was due to higher inherent GH content in mithun plasma collected from an aged (>10 years) senile mithun. For the biological validation of assay, two mithuns were administered with synthetic bovine GH‐releasing factor (GRF; 10 µg/100 kg body weight; intravenous) and another two were administered sterile normal saline (controls). Jugular blood samples were collected at ?60, ?45, ?30, ?15, ?10, ?5, 0, 5, 10, 15, 30 min and thereafter at 15‐min intervals beginning 1 hour before GRF injection up to 8‐hr post treatment, and samples were assayed for plasma GH. In two animals, a peak of GH was recorded at 15 min of GRF administration, which confirms the biological validation of the EIA. Plasma GH estimated in blood samples collected for 6 consecutive weeks from two different age groups of mithun (Group I, age 0–3 months; Group II, age 3–4 yr) showed higher (P < 0.0001) mean plasma GH in younger than in adult mithuns and consequently higher growth rates in the younger group. A parallelism test conducted between a buffer standard curve of bovine GH and GH measured from serial dilution of mithun plasma containing high concentration of endogenous GH showed good parallelism with a standard curve. In conclusion, the EIA developed for GH determination in mithun blood plasma is sufficiently reliable, economic, and sensitive enough to estimate mithun GH in all physiologic variations. Zoo Biol 0:1–11, 2005. © 2005 Wiley‐Liss, Inc.     

尼罗罗非鱼生长激素及其受体的cDNA克隆与mRNA表达的雌雄差异

尼罗罗非鱼(Oreochromis niloticus)雌雄鱼生长差异明显,为了探讨其原因,本文采用RT-PCR方法克隆了尼罗罗非鱼生长激素(Growthhormone,GH)及其受体(Growth hormone receptor,GHR)的cDNA序列,并应用半定量RT-PCR方法比较了雌、雄尼罗罗非鱼垂体GHmRNA、肝脏GHRmRNA、肌肉GHRmRNA的表达差异。序列分析表明:GH开放阅读框为615bp,共编码204个氨基酸;GHR开放阅读框为1908bp,共编码635个氨基酸。以RT-PCR方法研究了GH、GHR在各组织的分布情况,结果表明:GH仅在垂体中检测到有表达,而GHR在所检测的18种组织中均有表达,其中以肝脏、肌肉、性腺、下丘脑、胸腺表达量较高。以半定量RT-PCR方法进一步比较了雌、雄尼罗罗非鱼垂体GHmRNA、肝脏GHRmRNA、肌肉GHRmRNA的表达量,结果表明:雄鱼垂体GHmRNA和肝脏GHRmRNA的表达量均显著高于雌鱼,肌肉GHRmRNA的表达量则无显著差异,推测垂体GHmRNA和肝脏GHRmRNA表达的雌雄差异是尼罗罗非鱼雌雄生长差异的主要原因之一。     

Profiles of growth hormone and insulin secretion, and glucose response to insulin in growing Japanese Black heifers (beef type): comparison with Holstein heifers (dairy type)

Nine Japanese Black and 10 Holstein heifers ranging from 1 week (wk) to 18 months (mo) old received a single bolus intravenous injection of GH-releasing factor (GRF, 0.25-microg/kg BW), glucose (112.5-mg/kg BW) or insulin (0.2-U/kg BW) at various stages through 18 mo of age. The GH secretory response to exogenous GRF in Japanese Black heifers was lower than that in Holstein heifers at all stages of growth. While insulin secretory function was not very different in both breeds from 1 to 12 mo of age, the insulin response was much higher in Japanese Black heifers than in Holstein heifers after sexual maturation. The degree of decrease in plasma glucose following insulin injection was similar in both breeds at each stage of growth. It is concluded that compared with Holstein heifers, Japanese Black heifers have lower GH and higher insulin secretory functions, and that the two breeds have similar glucose response to insulin.     

Immunoreactive neuronal pathways of growth hormone-releasing hormone (GRH) in the brain and pituitary of the teleost Gadus morhua

Summary Using an antiserum directed against the C-terminus of hGRH(1–44)NH₂ and another recognizing the mid portion to C-terminal of hGRH(1–40)OH, we identify two immunocytochemically distinct GRH-immunoreactive systems in the brain of the codfish, Gadus morhua. The antiserum directed against GRF(1–44)NH₂ stains cell bodies exclusively in the rostral pars distalis. The other antiserum immunoreactive with GRF(1–40)OH reacts with a population of parvocellular and magnocellular neuronal cell bodies in the hypothalamus and with two major axonal pathways which project toward the median eminence and terminate primarily in the pars nervosa. These results indicate the presence of at least two forms of hGRH-like peptides in the teleost which may have different roles in the regulation of pituitary function.