Dynamics of the responses in secretion of luteinising hormone, leptin and insulin following an acute increase in nutrition in mature male sheep

2004 ◽  
Vol 16 (8) ◽  
pp. 823 ◽  
Author(s):  
Song Zhang ◽  
Dominique Blache ◽  
Margaret A. Blackberry ◽  
Graeme B. Martin
Keyword(s):  
Luteinising Hormone ◽  
Control Period ◽  
Dietary Treatment ◽  
Pulse Frequency ◽  
Diet Group ◽  
Metabolic Hormones ◽  
Group A ◽  
Acute Increase ◽  
Gonadotrophin Releasing Hormone ◽  
Male Sheep

In Merino rams, an increase in the plane of nutrition increases the frequency of luteinising hormone (LH) pulses within a few days and this response is correlated with changes in the circulating concentrations of metabolic hormones. To analyse early dynamic aspects of these responses, we studied mature rams fed with diets that contained either low or high amounts of energy and protein. Jugular blood was sampled every 20 min for 96 h, including a control period of 24 h before the change of diet in the high-diet group. In the high-diet group, a significant increase in LH pulse frequency was first detected 6 h after the increase in nutrition on Day 1 and the frequency remained significantly elevated throughout the 72-h treatment period, except for a 12-h period on Day 2. Following the change of diet, insulin concentrations increased within 3 h and leptin concentrations increased within 7 h, after which time the concentrations of both hormones remained high. Dietary treatment did not affect the concentrations of thyroxine or insulin-like growth factor-I, but the high diet increased the concentrations of tri-iodothyronine. These observations are consistent with insulin and leptin playing a role in the early activation of the gonadotrophin-releasing hormone–LH axis by nutritional inputs.

scholarly journals Hypothalamic responses to peripheral glucose infusion in food-restricted sheep are influenced by photoperiod

2005 ◽  
Vol 184 (3) ◽  
pp. 515-525 ◽  
Author(s):  
Z A Archer ◽  
S M Rhind ◽  
P A Findlay ◽  
C E Kyle ◽  
M C Barber ◽  
...  
Keyword(s):  
Gene Expression ◽  
Weight Maintenance ◽  
Plasma Concentrations ◽  
Insulin Receptors ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Hypothalamic Arcuate Nucleus ◽  
Maintain Body Weight ◽  
Gonadotrophin Releasing Hormone ◽  
Male Sheep

Nutritional feedback provided by systemic hormones, such as insulin and leptin, influences reproductive neuroendocrine output within the hypothalamus, yet the mechanisms and their interaction with photoperiodic cues remain unresolved in seasonal species. Here, peripheral glucose (G) infusion was used to increase endogenous concentrations of insulin and leptin in food-restricted sheep kept in either long-day (LD) or short-day (SD) photoperiod, and responses were examined in terms of pulsatile luteinising hormone (LH) (gonadotrophin-releasing hormone by inference) output and hypothalamic gene expression for nutritionally sensitive neuropeptides and receptors. We addressed the hypothesis that these hypothalamic responses were correlated and influenced by photoperiod. Oestradiol-implanted, castrated male sheep were kept 16 weeks in SD (8 h light/day) or LD (16 h light/day) and then transferred to the opposite photoperiods for 8 weeks, during which food was restricted to 90% requirement to maintain body weight (maintenance). For the final 6 days, food was reduced to 75% maintenance, and sheep in both photoperiods were infused intravenously with G (60 mM/h) or saline (S) (n=8/group). G-infused sheep had higher mean plasma concentrations of G, insulin and leptin than S-infused sheep, with no effect of photoperiod. In LD, but not in SD, G infusion increased LH pulse frequency and pulse amplitude. In LD, but not in SD, gene expression in the hypothalamic arcuate nucleus was lower in G- than S-infused sheep for neuropeptide Y (NPY) and agouti-related peptide (AGRP) and was higher in G- than S-infused sheep for pro-opiomelanocortin (POMC). Gene expression for leptin and insulin receptors was not affected by photoperiod or infusion. These results are consistent with the involvement of NPY, AGRP and POMC in mediating the reproductive neuroendocrine response to increased systemic nutritional feedback, and they support the hypothesis that hypothalamic responses to nutritional feedback are influenced by photoperiod in sheep.

To Study the Deteriorating Effects of Lithium Carbonate on Thyroid Gland - A Study in Albino Rats

2021 ◽  
Vol 15 (12) ◽  
pp. 3292-3293
Author(s):  
Tazeen Kohari ◽  
Zaffar Iqbal Malik ◽  
Aftab Ahmad ◽  
Rana M. Asad Khan
Keyword(s):  
Thyroid Gland ◽  
Harmful Effect ◽  
Lithium Carbonate ◽  
Diet Group ◽  
Human Thyroid ◽  
Control Group ◽  
Albino Rats ◽  
Weight Changes ◽  
Group A ◽  
Group B

Background: The human thyroid gland is located in the front of neck. It consists of two lobes. The two lobes are joined with each other by isthmus. The mood stabilizer Lithium Caronate has deleterious effects on the thyroid gland. Aim: To observe and report the data of the harmful effect of Lithium on the weight changes of thyroid gland. Methods: Sixteen rats were selected for this experimental study. The rodents were divided into two groups. Group A comprised of eight animals which were given laboratory diet, Group B contained eight albinos who were given Tablet Lithium Carbonate in powder form at a dose of 60 mg/day for four weeks. After completion of the study time animals were sacrificed and thyroid gland weight were recorded and compared in both groups. Results: The results in both groups were recorded and compared .It was reported that Group B animals had a highly significantly decreased thyroid weight after four weeks Lithium ingestion than Group A control group. Conclusion: The results of our study concluded that Lithium Carbonate damages thyroid glandular tissue and causes its weight to decline. Key words: Thyroid gland, Isthmus, deteriorating

Effect of chronic food restriction on pulsatile luteinizing hormone secretion and hypothalamic neuropeptide Y gene expression in castrate male sheep

1997 ◽  
Vol 152 (2) ◽  
pp. 329-337 ◽  
Author(s):  
C L Adam ◽  
P A Findlay ◽  
C E Kyle ◽  
P Young ◽  
J G Mercer
Keyword(s):  
Gene Expression ◽  
Neuropeptide Y ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
High Energy ◽  
Low Energy ◽  
High Protein ◽  
Castrate Male ◽  
Low Protein ◽  
Male Sheep

Abstract Castrate male sheep (wethers, average liveweight 38 ± 0·6 kg) were given one of the following diets for 10 weeks followed by euthanasia (n=8/group): high-energy high-protein providing 1·5 times the energy required to maintain liveweight (maintenance) (group 1·5M), low-energy low-protein at 0·5 maintenance (0·5M), or low-energy high-protein at 0·5 maintenance (0·5M+P). 1·5M wethers gained 22% liveweight whereas 0·5M and 0·5M+P wethers lost 18 and 13% liveweight respectively. Relative to the 1·5M group, the 0·5M and 0·5M+P groups had similar plasma concentrations of glucose and cortisol throughout, but elevated non-esterified fatty acids (P<0·001) and reduced IGF-I and insulin (P<0·05, 0·01 or 0·001) from 1 week onwards. Each week blood samples were taken every 12 min for 4 h and plasma assayed for LH. Mean concentration over 4 h, LH pulse frequency and LH pulse amplitude showed no progressive change in 1·5M sheep. However, in both 0·5M and 0·5M+P groups mean LH increased (P<0·001 and P<0·01 respectively), pulse frequency decreased (P<0·01 and P<0·01) and pulse amplitude increased (P<0·001 and P<0·01) over the 10-week period. Anterior pituitary LH content was greater in 0·5M (P<0·01) and 0·5M+P (P<0·05) than in 1·5M sheep. Coronal sections (20 μm) of hypothalamic brain tissue were subjected to in situ hybridisation to determine gene expression for neuropeptide Y (NPY). NPY mRNA was concentrated in the arcuate nucleus and median eminence, with total amounts greater in both 0·5M (310%, P<0·001) and 0·5M+P (333%, P<0·01) groups than in 1·5M sheep (100%). These data reveal that chronic low dietary energy intake by long-term castrates, with high or low protein intake, reduces LH pulse frequency but increases the circulating levels of LH by virtue of an increase in pulse amplitude, and concomitantly increases hypothalamic NPY gene expression. Journal of Endocrinology (1997) 152, 329–337

scholarly journals Effect of calfhood nutrition on metabolic hormones, gonadotropins, and estradiol concentrations and on reproductive organ development in beef heifer calves

2020 ◽  
Vol 98 (10) ◽  
Author(s):  
Alan K Kelly ◽  
Colin Byrne ◽  
Mark McGee ◽  
George A Perry ◽  
Mark A Crowe ◽  
...  
Keyword(s):  
Anterior Pituitary ◽  
Reproductive Tract ◽  
Ovarian Tissue ◽  
Area Under The Curve ◽  
Dietary Treatment ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Ovarian Surface ◽  
Time Interaction ◽  
Beef Heifer

Abstract This study examined the effect of plane of nutrition on the endocrinological regulation of the hypothalamic–pituitary–ovarian (HPO) axis in beef heifer calves during a critical sexual developmental window early in calf hood. Forty Holstein-Friesian × Angus heifers (mean age 19 d, SEM = 0.63) were assigned to a high (HI; ADG 1.2 kg) or moderate (MOD; ADG 0.50 kg) nutritional level from 3 to 21 wk of life. Intake was recorded using an electronic calf feeding system, BW was recorded weekly, and blood samples were collected on the week of age 5, 10, 15, and 20 for metabolite, reproductive, and metabolic hormone determination. At 19 wk of age, on sequential days, an 8-h window bleed was carried out for luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol analysis. To characterize anterior pituitary gland function, an intravenous GnRH challenge was conducted (19 wk of age). Blood was collected via a jugular catheter every 15 min for 135 min for the analysis of LH, FSH, and estradiol. Calves were subsequently euthanized at 21 wk of age; the anterior pituitary, metabolic organs, and reproductive tract were weighed, and ovarian surface follicular numbers and oocytes recovered were recorded. Mean ADG was 1.18 and 0.50 kg for HI and MOD, respectively, resulting in a 76.6-kg difference in BW (P &lt; 0.001). Blood insulin, glucose, and IGF-1 concentrations were greater (P &lt; 0.001) for HI compared with MOD. There was a diet × time interaction for leptin (P &lt; 0.01); concentrations were greater in HI compared with MOD at 20 wk of age with no difference between treatments before this. Dietary treatment did not alter the concentrations of adiponectin or anti-mullerian hormone. There was a diet × time interaction for FSH, whereby MOD had greater concentrations than HI at 10, 15, and 20, but not at 5 wk of age. Over the duration of an 8-h window bleed (19 wk of age), serum concentrations of LH, LH pulse frequency, and LH pulse amplitude were unaffected by treatment, whereas FSH (0.23 vs. 0.43 ng/mL) and estradiol (0.53 vs. 0.38 ng/mL) concentrations were less than and greater, respectively, for HI than MOD (P &lt; 0.05). Likewise, following a GnRH challenge, the area under the curve analysis revealed greater (P &lt; 0.01) estradiol and lesser (P &lt; 0.01) FSH concentrations in calves on the HI relative to MOD diet, whereas concentrations of LH were unaffected (P = 0.26) between treatments. Ovarian surface follicle numbers were greater (P &lt; 0.05) in HI compared with MOD. Total reproductive tract, uterus, and ovarian tissue expressed relative to BW were greater (P &lt; 0.05) for HI compared with MOD. In conclusion, enhanced nutrition in early calfhood advances the ontogeny development of the HPO axis.

THE EFFECT OF CYPROTERONE ACETATE ON THE PLASMA GONADOTROPHIN RESPONSE TO GONADOTROPHIN RELEASING HORMONE

1976 ◽  
Vol 81 (3) ◽  
pp. 680-684 ◽  
Author(s):  
Richard A. Donald ◽  
Eric A. Espiner ◽  
R. John Cowles ◽  
Joy E. Fazackerley
Keyword(s):  
Testosterone Level ◽  
Cyproterone Acetate ◽  
Luteinising Hormone ◽  
Follicle Stimulating Hormone ◽  
Plasma Testosterone ◽  
Plasma Testosterone Level ◽  
Releasing Hormone ◽  
Lh Release ◽  
Gonadotrophin Releasing Hormone ◽  
Male Patients

ABSTRACT Cyproterone acetate (100–150 mg daily) was administered to 8 male patients with excessive libido. Within 3 months a significant fall (P < 0.02) in plasma testosterone was demonstrated. The plasma luteinising hormone (LH) and follicle stimulating hormone (FSH) responses to gonadotrophin releasing hormone (LH/FSH-RH) were also significantly impaired (P < 0.05). A direct correlation between the resting plasma testosterone level and the LH response to LH/FSH-RH was demonstrated (r = 0.743). It is concluded that the fall in plasma testosterone levels in patients receiving cyproterone acetate may be attributed to suppression of LH release, rather than an antiandrogen effect on the testis or hypothalamus.

scholarly journals Effect of Keishibukuryogan on Endothelial Function in Patients with at Least One Component of the Diagnostic Criteria for Metabolic Syndrome: A Controlled Clinical Trial with Crossover Design

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Yutaka Nagata ◽  
Hirozo Goto ◽  
Hiroaki Hikiami ◽  
Tatsuya Nogami ◽  
Makoto Fujimoto ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Clinical Trial ◽  
Endothelial Function ◽  
Reactive Hyperemia ◽  
Control Period ◽  
Crossover Design ◽  
Controlled Clinical Trial ◽  
Related Factors ◽  
Group A ◽  
Group B

We evaluated the effect of keishibukuryogan (KBG; Guizhi-Fuling-Wan), a traditional Japanese (Kampo) formula, on endothelial function assessed by reactive hyperemia peripheral arterial tonometry (Endo-PAT2000) in patients with metabolic syndrome-related factors by controlled clinical trial with crossover design. Ninety-two patients were assigned to group A (first KBG-treatment period, then control period; each lasting 4 weeks, with about one-year interval) or group B (first control, then KBG-treatment). In forty-nine (27, group A; 22, group B) patients completing all tests, the mean value of the natural logarithmic-scaled reactive hyperemia index (L_RHI) increased and those of serum nonesterified fatty acid (NEFA), malondialdehyde, and soluble vascular cell adhesion molecule 1 decreased significantly during the KBG-treatment period, but not during the control period, and 4-week changes of L_RHI, NEFA, and malondialdehyde between the 2 periods showed significance. These results suggest that KBG has beneficial effect on endothelial function in patients with metabolic syndrome-related factors.

Influence of Sodium on Experimental Renovascular Hypertension in Rats

1980 ◽  
Vol 59 (s6) ◽  
pp. 149s-151s ◽  
Author(s):  
C. M. Taquini ◽  
A. Gallo ◽  
N. Basso ◽  
A. C. Taquini
Keyword(s):  
Plasma Renin Activity ◽  
Control Period ◽  
Plasma Renin ◽  
Diet Group ◽  
Renin Activity ◽  
Sodium Diet ◽  
Low Sodium Diet ◽  
Low Sodium ◽  
Group 2 ◽  
Group 1

1. Rats on normal sodium diet (group 1) and on chronically maintained low sodium diet (group 2) were studied during a control period, after clipping the renal artery (two-kidney, one-clip hypertension) and after nephrectomy (one-kidney, one-clip hypertension). 2. The low sodium diet neither prevented the development nor changed the severity of two-kidney, one-clip hypertension, and the latter was not accompanied by an increase in plasma renin activity. 3. After nephrectomy arterial pressure further increased and plasma renin activity decreased in group 1, and both remained unchanged in group 2. 4. Blood volume was the same in both groups 10 days before and 10 days after nephrectomy. 5. Sodium does not seem to be ‘necessary’ in the two-kidney, one-clip hypertension although it may play an enhancing role in the one-kidney model.

Effect of the body condition of ewes on the secretion of LH and FSH and the pituitary response to gonadotrophin-releasing hormone

1989 ◽  
Vol 120 (3) ◽  
pp. 497-502 ◽  
Author(s):  
S. M. Rhind ◽  
S. McMillen ◽  
W. A. C. McKelvey ◽  
F. F. Rodriguez-Herrejon ◽  
A. S. McNeilly
Keyword(s):  
Body Condition ◽  
Luteal Phase ◽  
Body Condition Score ◽  
Pulse Amplitude ◽  
Ovarian Hormones ◽  
Pulse Frequency ◽  
Follicular Phase ◽  
High Body ◽  
Condition Score ◽  
Gonadotrophin Releasing Hormone

ABSTRACT The effects of body fat content (body condition) of ewes on hypothalamic activity and gonadotrophin-releasing hormone (GnRH) secretion and on pituitary sensitivity to GnRH were investigated using Scottish Blackface ewes. Two groups of 12 ewes were fed so that they achieved either a high body condition score (2·98, s.e.m. = 0·046; approximately 27% of empty body weight as fat) or a low body condition score (1·94, s.e.m. = 0·031; approximately 19% of empty body weight as fat) by 4 weeks before the period of study. Thereafter, they were differentially fed so that the difference in mean condition score was maintained. Oestrus was synchronized, and on day 11 of the subsequent cycle half of the ewes of each group were ovariectomized. On day 12, the remaining ewes were injected (i.m.) with 100 μg prostaglandin F2α analogue and ovariectomized 30 h later. Numbers of large ovarian follicles and corpora lutea present at ovariectomy were recorded. Blood samples were collected at 15-min intervals for 12 h on day 10 of the cycle (luteal phase) and at 10-min intervals from 24 to 30 h after prostaglandin injection (follicular phase). At days 2 and 7 after ovariectomy, samples were collected at 15-min intervals for 8 h and ewes were then injected with 10 μg GnRH and samples were collected for a further 3 h. Samples were assayed for LH and FSH. Ewes in high body condition had more more large follicles than ewes in low body condition during the luteal phase (15·3 vs 6·5; P < 0·05) and follicular phase (11·5 vs 7·0; NS) and a slightly higher mean ovulation rate (1·50 vs 1·20; NS). However, during the luteal and follicular phases of the cycle before ovariectomy there was no effect of condition score on mean LH or FSH concentrations or mean LH pulse frequency or pulse amplitude. Two days after ovariectomy, ewes of high body condition had a higher mean LH pulse frequency than ewes of low body condition (P < 0·05) and higher mean FSH concentrations (P < 0·05). Mean LH concentration and pulse amplitude were not affected. LH and FSH profiles were not affected by body condition on day 7. GnRH-induced increases in LH and FSH concentrations on days 2 and 7 were not affected by body condition. At day 7, but not day 2, ewes ovariectomized during the luteal phase of the cycle had a significantly (P < 0·05) greater GnRH-induced LH release compared with ewes ovariectomized during the follicular phase. It is concluded that body condition directly affects hypothalamic activity and GnRH secretion, but not pituitary sensitivity to GnRH, and that effects on reproductive performance are also mediated through changes in ovarian hormones or in hypothalamo-pituitary sensitivity to ovarian hormones. Journal of Endocrinology (1989) 120, 497–502

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