Serum concentrations of luteinizing hormone, growth hormone, and cortisol in gilts treated with N-methyl-D,L-aspartate during the estrous cycle or after ovariectomy.

1998 ◽  
Vol 76 (8) ◽  
pp. 2162 ◽  
Author(s):  
M J Estienne ◽  
W F Hurlock ◽  
C R Barb
Keyword(s):  
Growth Hormone ◽  
Luteinizing Hormone ◽  
Estrous Cycle ◽  
Serum Concentrations

Growth hormone, insulin, glucose, cortisol, luteinizing hormone, and diabetes in beagle bitches treated with medroxyprogesterone acetate

1987 ◽  
Vol 116 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Joseph P. McCann ◽  
Norman Altszuler ◽  
Jennifer Hampshire ◽  
Patrick W. Concannon
Keyword(s):  
Insulin Resistance ◽  
Growth Hormone ◽  
Luteinizing Hormone ◽  
Medroxyprogesterone Acetate ◽  
Serum Concentrations ◽  
Cortisol Levels ◽  
High Doses ◽  
And Control

Abstract. Adult beagle bitches (20 to 101 months old) received medroxyprogesterone acetate (MPA; 75 mg/kg, im) or control vehicle at 3 month intervals. Changes in serum concentrations of GH, insulin and glucose were determined in 18 MPA-treated and 6 of 12 control bitches at 0, 2, 4, 8, 16 and 17–24 months of treatment (Exp. I). GH, LH and cortisol responsiveness to combined im injection of TRH (10 μg/kg), GnRH (10 μg/kg), and ACTH (5 μg/kg) was determined in 9 MPA-treated and 9 control bitches at 17 months of treatment (Exp. II). In Exp. I, serum concentrations of GH at month 2 (2.6 ± 0.3 μg/l), 4 (3.0 ± 0.3 μg/l), 8 (4.0 ± 1.2 μg/l), 16 (8.5 ± 1.7 μg/l), and 17–24 (21.2 ± 4.1 μg/l) of treatment were greater (P < 0.05) than pretreatment (1.4 ± 0.07 μg/l) and control (1.5 ± 0.1 μg/l) levels. The increase in GH at 2 months preceded (N = 4) or coincided (N = 2) with the development of hyperinsulinaemia and insulin resistance in 6 of the 18 treated bitches, two of which became diabetic by 17 months of MPA treatment. GH (24.6 ± 5.0 vs 11.4 ± 2.1 μg/l) and insulin (308 ± 77 vs 119 ± 9 pmol/l) concentrations were greater (P < 0.05) in older (49 ± 4 months; N = 12) than in the younger (26 ± 2 months; N = 6) treated bitches at 17–24 months of MPA treatment. In Exp. II, pretreatment concentrations of GH were increased (9.8 ± 3.0 vs 1.4 ± 0.1 μg/l, P < 0.01), cortisol levels decreased (12 ± 5 vs 72 ± 10 nmol/l, P < 0.01) and LH concentrations (0.9 ± 0.2 μg/l) unaffected in MPA-treated bitches. After injection of tropic hormones, GH was unchanged, whereas the rises in LH and cortisol levels were less (P < 0.01) in MPA-treated bitches than in control bitches. The results demonstrate that high doses of MPA increase GH concentrations within 2 months and that the GH overproduction and its diabetogenic-like effects were more pronounced in the older than in the younger treated bitches.

scholarly journals Central infusion of leptin into well-fed and undernourished ewe lambs: effects on feed intake and serum concentrations of growth hormone and luteinizing hormone

2001 ◽  
Vol 168 (2) ◽  
pp. 317-324 ◽  
Author(s):  
CD Morrison ◽  
JA Daniel ◽  
BJ Holmberg ◽  
J Djiane ◽  
N Raver ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Luteinizing Hormone ◽  
Feed Intake ◽  
Serum Concentrations ◽  
Functional Link ◽  
Serum Leptin ◽  
Ewe Lambs ◽  
Hypothalamic Function ◽  
Maintenance Requirements ◽  
Serum Gh

Leptin has been implicated in the regulation of feed intake, growth, and reproduction. The objective of this study was to determine if centrally administered leptin would affect feed intake and the secretion of growth hormone (GH) and luteinizing hormone (LH) in ewe lambs. Eighteen ewe lambs were ovariectomized and fitted with intracerebroventricular (i.c.v.) cannulae. Lambs were randomly assigned to receive either a maintenance diet (fed), or a diet that provided 38% of maintenance requirements (diet-restricted) for 14 weeks. Subsequently, recombinant ovine leptin or vehicle was continuously infused, via i.c.v. cannulae, in a linearly increasing dose for 8 days, reaching a maximum of 1.25 microg/kg per h. Feed intake was recorded on days -1 to 7. Blood was collected via jugular cannulae every 10 min for 4 h on days 0, 2, 4, 6 and 8 for the determination of serum leptin, insulin, LH and GH. Leptin suppressed feed intake in fed lambs on days 4 to 7 (P<0.001), but had no effect on feed intake in diet-restricted lambs (P>0.25). Fed lambs had greater serum concentrations of leptin than diet-restricted lambs (P=0.007). Also, although not different on day 0 (pretreatment), on day 8 serum leptin concentrations were greater in leptin-treated lambs than in saline-treated lambs (P=0.003). Insulin was lower in diet-restricted than in fed lambs (P=0.003), but was not affected by leptin treatment (P=0.82). LH pulse frequencies were lower in diet-restricted lambs than in fed lambs (P=0.038), but were not affected by leptin treatment (P=0.85). Mean serum GH was greater in diet-restricted than in fed lambs (P<0.01). In diet-restricted lambs treated with leptin or saline, mean GH did not differ on day 0, but increased in response to leptin treatment (P<0.006). Treatment of fed lambs with leptin did not affect serum GH (P>0.32). From this work, we propose that leptin represents an important functional link between adipose stores and hypothalamic function in ruminants. We demonstrate that leptin concentrations change in response to reduced nutritional status, and that leptin has the ability to regulate multiple physiological processes in lambs, including both feed intake and secretion of GH.

FEEDBACK CONTROL OF FSH IN THE MALE: ROLE OF OESTROGEN

1973 ◽  
Vol 74 (3) ◽  
pp. 449-460 ◽  
Author(s):  
Patrick C. Walsh ◽  
Ronald S. Swerdloff ◽  
William D. Odell
Keyword(s):  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Oestrogen Therapy ◽  
Serum Concentrations ◽  
Elderly Men ◽  
Normal Range ◽  
Oestrogen Treatment ◽  
Serum Lh ◽  
Higher Doses

ABSTRACT Serum follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured by radioimmunoassay in a group of elderly men following castration and oestrogen therapy. Prior to orchiectomy, mean serum concentrations of LH and FSH were within the normal range. Two days following castration, serum LH concentrations increased in all eight patients; higher levels of LH were subsequently measured in all but one patient after periods of time ranging from 49 to 210 days. Serum FSH levels, measured in three patients following castration, increased in a pattern parallel to LH changes. Ethinyl oestradiol (EOe) in doses ranging from 5 to 300 μg/day was administered to ten men who had been castrated 3 to 72 months earlier. Oestrogen treatment suppressed both LH and FSH in a parellel manner in nine of ten patients. LH was first suppressed to intact levels in one of eight patients treated with 20 μg/day of EOe, in two of six patients treated with 50 μg/day, and in one patient by 80 μg/day. FSH was not suppressed to precastration levels until 50 μg/day of EOe was administered; this dose suppressed three of six patients. Higher doses of EOe (150–300 μg/day) suppressed both LH and FSH to levels below the sensitivity of the assay. These data fail to demonstrate any differential effect of oestrogen on LH and FSH release.

Androgenic and oestrogenic steroid participation in feedback control of luteinizing hormone secretion in male sheep

1983 ◽  
Vol 102 (4) ◽  
pp. 499-504 ◽  
Author(s):  
M. J. D'Occhio ◽  
B. D. Schanbacher ◽  
J. E. Kinder
Keyword(s):  
Luteinizing Hormone ◽  
Pulse Generator ◽  
Hormone Secretion ◽  
Pulse Interval ◽  
Serum Concentrations ◽  
Luteinizing Hormone Secretion ◽  
Lh Release ◽  
Lh Secretion ◽  
Additional Feedback ◽  
Male Sheep

Abstract. The acute castrate ram (wether) was used as an experimental model to investigate the site(s) of feedback on luteinizing hormone (LH) by testosterone, dihydrotestosterone and oestradiol. At the time of castration, wethers were implanted subdermally with Silastic capsules containing either crystalline testosterone (three 30 cm capsules), dihydrotestosterone (five 30 cm capsules) or oestradiol (one 6.5 cm capsule). Blood samples were taken at 10 min intervals for 6 h 2 weeks after implantation to determine serum steroid concentrations and to characterize the patterns of LH secretion. Pituitary LH response to exogenous LRH (5 ng/kg body weight) were also determined at the same time. The steroid implants produced serum concentrations of the respective hormones which were either one-third (testosterone) or two-to-four times (dihydrotestosterone, oestradiol) the levels measured in rams at the time of castration. Non-implanted wethers showed rhythmic pulses of LH (pulse interval 40–60 min) and had elevated LH levels (16.1 ± 1.6 ng/ml; mean ± se) 2 weeks after castration. All three steroids suppressed pulsatile LH release and reduced mean LH levels (to below 3 ng/ml) and pituitary LH responses to LRH. Inhibition of pulsatile LH secretion by all three steroids indicated that testosterone as well as its androgenic and oestrogenic metabolites can inhibit the LRH pulse generator in the hypothalamus. Additional feedback on the pituitary was indicated by the dampened LH responses to exogenous LRH.

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