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Nahar A, Kadokawa H. Expression of macrophage migration inhibitory factor (MIF) in bovine oviducts is higher in the postovulatory phase than during the oestrus and luteal phase. Reprod Fertil Dev 2018; 29:1521-1529. [PMID: 27465152 DOI: 10.1071/rd15546] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 06/21/2016] [Indexed: 11/23/2022] Open
Abstract
Whether macrophage migration inhibitory factor (MIF) in the bovine oviduct is important for early embryogenesis has not been well substantiated. The aim of the present study was to test the hypothesis that bovine oviduct expresses higher levels of MIF during the post-ovulation phase. Both ampullary and isthmic samples were collected from Japanese black heifers during oestrus (Day 0; n=5), postovulation (Day 3; n=6) and luteal phase (Days 9-12; n=5). MIF mRNA and protein were extracted from the ampullary and isthmic samples and their levels measured by real-time polymerase chain reaction and western blot analysis respectively. Fluorescent immunohistochemistry was performed on frozen ampullary and isthmic sections using antibodies against MIF. MIF mRNA and protein expression was higher in the postovulatory phase than during oestrus and the luteal phase (P<0.05). Fluorescent immunohistochemistry confirmed that in all phases of the oestrous cycle evaluated, the primary site of MIF expression in the ampulla and isthmus was the tunica mucosa. In conclusion, the bovine ampulla and isthmus have higher MIF expression during the postovulatory phase. Further studies are needed to clarify the role of MIF in bovine oviducts.
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Affiliation(s)
- Asrafun Nahar
- Faculty of Veterinary Medicine, Yamaguchi University, Yoshida 1677-1, Yamaguchi-shi, Yamaguchi-ken, 753-8515, Japan
| | - Hiroya Kadokawa
- Faculty of Veterinary Medicine, Yamaguchi University, Yoshida 1677-1, Yamaguchi-shi, Yamaguchi-ken, 753-8515, Japan
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Kereilwe O, Pandey K, Kadokawa H. Influence of brain plasmalogen changes on gonadotropin secretion from the cultured bovine anterior pituitary cells. Domest Anim Endocrinol 2018; 64:77-83. [PMID: 29754010 DOI: 10.1016/j.domaniend.2018.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 04/02/2018] [Accepted: 04/02/2018] [Indexed: 11/29/2022]
Abstract
We recently discovered that the orphan G-protein-coupled receptor (GPR) 61 colocalized with GnRH receptors (GnRHRs) on the surface of most of bovine gonadotrophs. A recent study suggested that ethanolamine plasmalogen (PI) is a ligand for GPR61 in mouse neuroblastoma. Therefore, this study evaluated the hypothesis that PI alters LH and FSH secretion from cultured bovine anterior pituitary (AP) cells. We prepared bovine AP cells from postpubertal heifers (26 mo old) and cultured the cells for 3.5 d. We treated the cells with increasing concentrations (0, 5, 50, 500, 5,000, 50,000, or 500,000 pg/mL) of phosphoethanolamine PI (PEPI) extracted from the bovine brain, or l-α-lysophosphatidylethanolamine PI (LEPI) extracted from the bovine brain, for 5 min before either no treatment or GnRH stimulation. The medium samples were harvested 2 h after culture for LH and FSH assays. Phosphoethanolamine PI (50-500 pg/mL) stimulated (P < 0.05) the basal secretion of FSH but not LH. Phosphoethanolamine PI at 50 pg/mL also enhanced (P < 0.05) GnRH-induced FSH secretion. However, higher doses (500-500,000 pg/mL) of PEPI suppressed GnRH-induced FSH secretion. Moreover, 50 to 500,000 pg/mL PEPI suppressed GnRH-induced LH secretion. None of the tested concentrations of LEPI showed any effect on basal or GnRH-induced LH or FSH secretion. Pretreatment with Sma and Mad pathway inhibitors suppressed FSH secretion induced by PEPI, whereas an extracellular signal-regulated kinase pathway inhibitor blocked the PEPI-induced suppression of GnRH-stimulated LH secretion. Therefore, PEPI, but not LEPI, extracted from the bovine brain, alters FSH and LH secretion from cultured AP cells. Further studies are required to decide whether PEPI binds to GPR61 and whether PEPI plays an important role in the control of gonadotropin secretion from gonadotrophs.
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Affiliation(s)
- O Kereilwe
- Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi-shi, Yamaguchi-ken, 1677-1, Japan
| | - K Pandey
- Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi-shi, Yamaguchi-ken, 1677-1, Japan
| | - H Kadokawa
- Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi-shi, Yamaguchi-ken, 1677-1, Japan.
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Pandey K, Kereilwe O, Kadokawa H. Heifers express G-protein coupled receptor 153 in anterior pituitary gonadotrophs in stage-dependent manner. Anim Sci J 2017; 89:60-71. [PMID: 28960688 DOI: 10.1111/asj.12920] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 08/03/2017] [Indexed: 12/26/2022]
Abstract
We recently found that orphan G-protein-coupled receptor (GPR)153 is expressed in the anterior pituitary (AP) of heifers, leading us to speculate that GPR153 colocalizes with gonadotropin-releasing hormone receptor (GnRHR) in the plasma membrane of gonadotrophs and is expressed at specific times of the reproductive cycle. To test this hypothesis, we examined the coexpression of GnRHR, GPR153, and either luteinizing hormone or follicle-stimulating hormone in AP tissue and cultured AP cells by immunofluorescence microscopy. GPR153 was detected in the gonadotrophs, and was colocalized with GnRHR in the plasma membrane. GPR153 was also detected in the cytoplasm of cultured gonadotrophs. Real-time PCR and western blot analyses found that expression was lower (P < 0.05) in AP tissues during early luteal phase as compared to pre-ovulation or late luteal phases. The 5'-flanking region of the GPR153 gene contained a consensus response element sequence for estrogen, but not for progesterone. These data suggest that some, but not all GPR153 colocalizes with GnRHR in the plasma membrane of gonadotrophs, and its expression changes stage-dependently in the bovine AP.
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Affiliation(s)
- Kiran Pandey
- Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Onalenna Kereilwe
- Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Hiroya Kadokawa
- Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
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Pandey K, Kereilwe O, Borromeo V, Kadokawa H. Heifers express G-protein coupled receptor 61 in anterior pituitary gonadotrophs in stage-dependent manner. Anim Reprod Sci 2017; 181:93-102. [DOI: 10.1016/j.anireprosci.2017.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/21/2017] [Accepted: 03/30/2017] [Indexed: 10/19/2022]
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Pandey K, Mizukami Y, Watanabe K, Sakaguti S, Kadokawa H. Deep sequencing of the transcriptome in the anterior pituitary of heifers before and after ovulation. J Vet Med Sci 2017; 79:1003-1012. [PMID: 28442638 PMCID: PMC5487774 DOI: 10.1292/jvms.16-0531] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We aimed to determine gene expression patterns in the anterior pituitary (AP) of heifers
before and after ovulation via deep sequencing of the transcriptome (RNA-seq) to identify
new genes and clarify important pathways. Heifers were slaughtered on the estrus day
(pre-ovulation; n=5) or 3 days after ovulation (post-ovulation; n=5) for AP collection. We
randomly selected 4 pre-ovulation and 4 post-ovulation APs, and the ribosomal RNA-depleted
poly (A)+RNA were prepared to assemble next-generation sequencing libraries. The bovine
APs expressed 12,769 annotated genes at pre- or post-ovulation. The sum of the reads per
kilobase of exon model per million mapped reads (RPKM) values of all transcriptomes were
599,676 ± 38,913 and 668,209 ± 23,690, and 32.2 ± 2.6% and 44.0 ± 4.4% of these
corresponded to the AP hormones in the APs of pre- and post-ovulation heifers,
respectively. The bovine AP showed differential expression of 396 genes
(P<0.05) in the pre- and post-ovulation APs. The 396 genes included
two G-protein-coupled receptor (GPCR) genes (GPR61 and
GPR153) and those encoding 13 binding proteins. The AP also expressed
259 receptor and other 364 binding proteins. Moreover, ingenuity pathway analysis for the
396 genes revealed (P=2.4 × 10−3) a canonical pathway linking
GPCR to cytoskeleton reorganization, actin polymerization, microtubule growth, and gene
expression. Thus, the present study clarified the novel genes found to be differentially
expressed before and after ovulation and clarified an important pathway in the AP.
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Affiliation(s)
- Kiran Pandey
- Joint Faculty of Veterinary Medicine, Yamaguchi University, Yoshida 1677-1, Yamaguchi-shi, Yamaguchi 753-8515, Japan
| | - Yoichi Mizukami
- Center for Gene Research, Yamaguchi University, Minami Kogushi 1-1-1, Ube-shi, Yamaguchi 755-8505, Japan
| | - Kenji Watanabe
- Center for Gene Research, Yamaguchi University, Minami Kogushi 1-1-1, Ube-shi, Yamaguchi 755-8505, Japan
| | - Syuiti Sakaguti
- Institute of Radioisotope Research and Education, Yamaguchi University, Minami Kogushi 1-1-1, Ube-shi, Yamaguchi 755-8505, Japan
| | - Hiroya Kadokawa
- Joint Faculty of Veterinary Medicine, Yamaguchi University, Yoshida 1677-1, Yamaguchi-shi, Yamaguchi 753-8515, Japan
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Rudolf FO, Kadokawa H. Cytoplasmic kinases downstream of GPR30 suppress gonadotropin-releasing hormone (GnRH)-induced luteinizing hormone secretion from bovine anterior pituitary cells. J Reprod Dev 2015; 62:65-9. [PMID: 26522383 PMCID: PMC4768779 DOI: 10.1262/jrd.2015-104] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
GPR30 is known as a membrane receptor for picomolar concentrations of estradiol. The GPR30-specific agonist
G1 causes a rapid, non-genomic suppression of gonadotropin-releasing hormone (GnRH)-induced luteinizing
hormone (LH) secretion from bovine anterior pituitary (AP) cells. A few studies have recently clarified that
protein kinase A (PKA) and phosphorylated extracellular signal-regulated kinase (pERK) might be involved in
cytoplasmic signaling pathways of GPR30 in other cells. Therefore, we tested the hypothesis that PKA and ERK
kinase (MEK) are important cytoplasmic mediators for GPR30-associated non-genomic suppression of GnRH-induced
LH secretion from bovine AP cells. Bovine AP cells (n = 8) were cultured for 3 days under steroid-free
conditions. The AP cells were previously treated for 30 min with one of the following: 5000 nM of PKA
inhibitor (H89), 1000 nM of MEK inhibitor (U0126), or a combination of H89 and U0126. Next, the AP cells were
treated with 0.01 nM estradiol for 5 min before GnRH stimulation. Estradiol treatment without inhibitor
pretreatment significantly suppressed GnRH-induced LH secretion (P < 0.01). In contrast, estradiol
treatment after pretreatment with H89, U0126 or their combination had no suppressive effect on GnRH-induced LH
secretion. The inhibitors also inhibited the G1 suppression of GnRH-induced LH secretion. Therefore, these
data supported the hypothesis that PKA and MEK (thus, also pERK) are the intracellular mediators downstream of
GPR30 that induce the non-genomic suppression of GnRH-induced LH secretion from bovine AP cells by estradiol
or G1.
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Affiliation(s)
- Faidiban O Rudolf
- Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi 753-8511, Japan
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7
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Kadokawa H, Aikawa K, Kimura K, Blache D, Williams IH, Martin GB. Links between de novo fatty acid synthesis and leptin secretion in bovine adipocytes. J Vet Med Sci 2007; 69:225-31. [PMID: 17409636 DOI: 10.1292/jvms.69.225] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Leptin secretion by adipose tissue is involved in many physiological control systems, including those that determine growth, development, body composition, milk production, and reproductive function. In the adipocyte of monogastric animals, malonyl CoA (coenzyme A) seems to link the flux of energy substrates to the control of leptin production. In this study, we tested this for ruminants by examining the effect of cerulenin, an inhibitor of de novo fatty acid synthesis at the step from malonyl CoA to palmitate, on leptin production by cultured bovine adipocytes derived from intermuscular fat. Purified preadipocytes were obtained by the ceiling culture method, and adipogenic media were used to induce their differentiation into adipocytes. We found that leptin concentrations increased significantly with time in culture, and with increases in glucose concentration. Addition of 2-deoxy-D-glucose to the medium, a competitive inhibitor of glucose transport and metabolism, suppressed leptin secretion. In media with high glucose concentrations, cerulenin enhanced leptin secretion. We conclude that, as in monogastrics, malonyl CoA may play a key role in the control of leptin secretion in ruminants.
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Affiliation(s)
- Hiroya Kadokawa
- Department of Veterinary Medicine, Faculty of Agricultural Science, University of Yamaguchi, Japan
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Celi P, Blache D, Blackberry MA, Martin GB. Intracerebroventricular infusion of leptin into mature merino rams of different metabolic status: effects on blood concentrations of glucose and reproductive and metabolic hormones. Reprod Domest Anim 2006; 41:79-90. [PMID: 16420334 DOI: 10.1111/j.1439-0531.2006.00637.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In mature Merino rams, nutrition is one of the external cues that most strongly affects the reproductive centres of the preoptic-hypothalamic continuum. The signalling pathways that link dietary status and the activity of the neurones that produce gonadotrophin-releasing hormone signals are thought to be partly hormonal in nature to reflect the amount of body reserves. Among the hormones thought to be involved are insulin and leptin. This study tested whether recombinant bovine leptin infused (0.4 microg/h) into the third cerebral ventricle would stimulate pulsatile luteinizing hormone (LH) secretion in mature Merino rams when their energy status was low or decreasing, during both chronic (fasting) and acute reductions of energy balance. Leptin may interact with other hormones that depend on energy availability, so we also monitored changes in circulating concentrations of insulin, thyroid hormones, growth hormone, prolactin and adrenocorticotrophin. Overall, our data do not support this hypothesis. The dietary regimes induced clear responses in the metabolic profiles of the animals but there was no clear effect of central leptin administration on LH pulse frequency. The relationships between the hormonal systems measured in the present study add weight to the contention that leptin plays only a permissive role in the nutritional control of the reproductive axis and that other hormonal signals (particularly insulin) or pathways are acting in concert with leptin to stimulate the reproductive axis.
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Affiliation(s)
- P Celi
- Faculty of Natural and Agricultural Sciences, School of Animal Biology, The University of Western Australia, Crawley, WA, Australia.
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9
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Amstalden M, Zieba DA, Edwards JF, Harms PG, Welsh TH, Stanko RL, Williams GL. Leptin acts at the bovine adenohypophysis to enhance basal and gonadotropin-releasing hormone-mediated release of luteinizing hormone: differential effects are dependent upon nutritional history. Biol Reprod 2003; 69:1539-44. [PMID: 12826579 DOI: 10.1095/biolreprod.103.018119] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Recombinant ovine leptin (oleptin) stimulates an acute increase in the secretion of LH in fasted, but not in normal-fed, cows through an augmentation of the magnitude of individual pulses of LH. Herein, we tested the hypothesis that this effect could be accounted for by functional changes at the adenohypophyseal (AP) level. Eleven ovariectomized, estradiol-implanted cows were assigned to one of two dietary groups: normal-fed (n = 6) and fasted (fasted for 72 h; n = 5). After the animals were killed, the adenohypophyses were collected and AP explants were perifused with Krebs-Ringer bicarbonate buffer (KRB) for a total of 6.5 h, including a 2-h treatment at 2.5 h with KRB or increasing doses of oleptin and a challenge at 4.5 h with 50 ng of GnRH. To test for effects of leptin at the hypothalamic level, explants encompassing the medial basal hypothalamus-infundibular complex (HYP) were incubated in KRB alone (control) or in KRB containing 1000 ng of oleptin. Basal release of LH from AP explants treated with leptin was greater (P < 0.02) than that from control-treated explants in fasted, but not in normal-fed, cows. To the contrary, leptin-treated explants from normal-fed, but not from fasted, cows released more (P < 0.001) LH in response to GnRH than control-treated tissues. Neither fasting nor leptin affected (P > 0.1) the secretion of GnRH from HYP explants. These observations support the hypothesis that leptin modulates the secretion of LH in mature cows, to a large extent, by its direct actions at the AP. Differential manifestations of these effects are dependent upon nutritional history.
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Affiliation(s)
- M Amstalden
- Animal Reproduction Laboratory, Texas A and M University Agricultural Research Station, Beeville, Texas 78102, USA
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10
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Tanaka T, Akaboshi N, Inoue Y, Kamomae H, Kaneda Y. Fasting-induced suppression of pulsatile luteinizing hormone secretion is related to body energy status in ovariectomized goats. Anim Reprod Sci 2002; 72:185-96. [PMID: 12137981 DOI: 10.1016/s0378-4320(02)00091-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The effect of energy status on the response of luteinizing hormone (LH) pulse frequency to acute short-term energy deficiency created by fasting in estradiol-treated ovariectomized Shiba goats was studied in two experiments. In experiment 1, eight goats whose mean body weight (BW) was 25.6 +/- 5.8 (mean +/- S.D.)kg were fed 500 g hay cubes daily for 1 week. Then they were fasted for 3 days. Blood samples were collected for 4 h at 6 min intervals on the last day of feeding, first, second and third day of fasting for LH analysis. The goats were divided into light (<24 kg, n = 4) and heavy (> or =24 kg, n = 4) groups for data analysis. There was no difference in LH pulse frequency between the last day of feeding and each day of fasting in the heavy group. LH pulse frequency was significantly (P < 0.05) suppressed on the second day (3.3 +/- 1.3 pulses/4 h) and on the third day (2.3 +/- 1.9 pulses/4 h) relative to the day prior to fasting (4.8 +/- 1.5 pulses/4 h) in the light group. In experiment 2, BW plus a body mass index (BMI (body weight (kg)/withers height (m)/body length (m))/10 [corrected]) were measured to define energy status. Nine goats (BW, 25.6 +/- 5.8 kg) were fed 500 g hay cubes daily for a week and then fasted for 3 days. Then they were divided into two groups offered either a maintenance (n = 4) or a restricted (n = 5) level of feeding for 4 weeks. The restricted level of feeding was 30% of maintenance requirement based on the BW recorded weekly. The feeding level was then adjusted to maintain BW for a further week followed by 3 day fasting for restricted animals. Blood samples were collected for 6 h at 10 min intervals on the day prior to fasting and on third day of fasting before and after the dietary manipulation. BW (26.6 +/- 2.2 to 26.8 +/- 3.8 kg) and gBMI (8.4 +/- 0.4 to 7.8 +/- 0.3) remained constant over the period prior to fasting for the maintenance animals but were significantly lower (P < 0.05) after 4 weeks for the restricted goats (BW, 26.3 +/- 2.1 to 21.5 +/- 2.4 kg; gBMI, 8.4 +/- 0.9 to 6.9 +/- 0.7). There was no significant difference in the LH pulse frequency between feeding and fasting day in both sampling periods in the maintenance group. In the restricted group, LH pulse frequency was not suppressed by fasting in the first sampling period (6.8 +/- 2.9 to 5.2 +/- 2.5 pulses/6 h), whereas it tended to be suppressed (4.8 +/- 3.1 to 1.6 +/- 2.3 pulses/6 h; P < 0.06) and was significantly (P < 0.05) correlated to body weight (r = 0.70) and gBMI (r = 0.81) after the dietary manipulation. These results suggest that the suppressive effect of short-term energy restriction (fasting) on pulsatile LH secretion is related to body energy status.
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Affiliation(s)
- Tomomi Tanaka
- Laboratory of Veterinary Reproduction, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai, Fuchu, Tokyo 183-8509, Japan.
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Amstalden M, Garcia MR, Stanko RL, Nizielski SE, Morrison CD, Keisler DH, Williams GL. Central infusion of recombinant ovine leptin normalizes plasma insulin and stimulates a novel hypersecretion of luteinizing hormone after short-term fasting in mature beef cows. Biol Reprod 2002; 66:1555-61. [PMID: 11967223 DOI: 10.1095/biolreprod66.5.1555] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The present studies tested the hypotheses that short-term fasting would reduce leptin gene expression and circulating concentrations of leptin and insulin in mature, ovariectomized, estradiol-implanted cows and that intracerebroventricular infusions of recombinant ovine leptin (oleptin) would attenuate reductions in insulin concentration and stimulate LH secretion. Ovariectomized cows were assigned to either control (normal fed; n = 6) or fasted (60 h of fasting; n = 7) groups and infused with 200 microg recombinant oleptin three times at hourly intervals on Day 2 (n = 6 per group). Fasting decreased plasma concentrations of insulin (P < 0.01) and leptin (P < 0.04) but, as expected, did not reduce plasma concentrations of glucose or any LH secretion variable. Central infusion of leptin on Day 2 increased (P < 0.01) plasma concentrations of leptin in both control and fasted groups. Concomitantly, leptin treatment increased plasma insulin (P < 0.01) and LH (P < 0.03) concentrations in fasted but not in control cows. Increases in overall mean and baseline concentrations of LH after leptin treatment were the result of an augmentation of the size of LH pulses. The effects of fasting on leptin gene expression and the potential diurnal effects on circulating leptin were examined in a group of cows (n = 12) not treated with leptin. Fasting for 60 h reduced (P < 0.001) leptin gene expression by 30%, and no diurnal effects on circulating leptin were observed. These results indicate that although short-term fasting does not reduce the frequency or amplitude of LH pulses or the concentration of LH in mature cows, this nutritional perturbation clearly sensitizes both the hypothalamic-pituitary axis and endocrine pancreas to exogenous leptin, which in these experiments resulted in heightened secretion of both LH and insulin.
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Affiliation(s)
- M Amstalden
- Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, 3507 Highway 59 E, Beeville, TX 78102, USA
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Amstalden M, Garcia MR, Williams SW, Stanko RL, Nizielski SE, Morrison CD, Keisler DH, Williams GL. Leptin gene expression, circulating leptin, and luteinizing hormone pulsatility are acutely responsive to short-term fasting in prepubertal heifers: relationships to circulating insulin and insulin-like growth factor I(1). Biol Reprod 2000; 63:127-33. [PMID: 10859251 DOI: 10.1095/biolreprod63.1.127] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
In the present study, we tested the hypothesis that short-term fasting would reduce leptin gene expression, circulating leptin, and LH pulsatility in prepubertal heifers in association with a decrease in circulating concentrations of insulin and insulin-like growth factor I (IGF-I). Twelve prepubertal crossbred heifers (mean +/- SD = 315 +/- 5 kg body weight) were assigned randomly to one of two treatments in two replicates: 1) control; normal feed consumption (n = 6) and 2) fasted; 48 h of total feed restriction (n = 6). Blood samples were collected at 15-min intervals for 8 h on Days 0 and 2 of the experiment and twice on Day 1. Subcutaneous fat samples were collected before treatment onset (Day -1) and at the end of the intensive blood sampling on Day 2. Acute feed restriction markedly reduced leptin mRNA in adipose tissue (P < 0.01) and circulating concentrations of leptin (P < 0.05), IGF-I (P < 0.01), and insulin (P = 0.05) as compared with controls on Day 2. Moreover, the treatment x day interaction (P < 0.076) and within-day contrasts (expressed as a percentage of Day 0 values) revealed that the mean frequency of LH pulses in the fasted group was lower (P < 0.06) than in controls on Day 2. Neither mean concentrations of growth hormone (GH) nor GH secretory dynamics were affected by acute feed restriction. Fasting-mediated decreases in leptin gene expression and circulating leptin, in association with reductions in secretion of IGF-I, insulin, and LH, provide a basis for investigating leptin as a hormone signaling energy status to the central reproductive axis in cattle.
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Affiliation(s)
- M Amstalden
- Animal Reproduction Laboratory, Texas A&M University Agricultural Research Station, Beeville, Texas 78102, USA
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