Spaceflight suppresses exercise-induced release of bioassayable growth hormone

1999 ◽  
Vol 87 (3) ◽  
pp. 1207-1212 ◽  
Author(s):  
G. E. McCall ◽  
C. Goulet ◽  
R. R. Roy ◽  
R. E. Grindeland ◽  
G. I. Boorman ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Plasma Concentrations ◽  
Bed Rest ◽  
Voluntary Contraction ◽  
Exercise Protocol ◽  
Acute Bout ◽  
Igf I ◽  
Muscle Afferent ◽  
Exercise Induced ◽  
Response To Exercise

We have reported that bed rest suppressed the release of bioassayable growth hormone (BGH) that normally occurs after an acute bout of unilateral plantar flexor exercise (G. E. McCall, C. Goulet, R. E. Grindeland, J. A. Hodgson, A. J. Bigbee, and V. R. Edgerton. J. Appl. Physiol. 83: 2086–2090, 1997). In the present study, the effects of spaceflight on the hormonal responses to this exercise protocol were examined. Four male astronauts on the National Aeronautics and Space Administration Shuttle Transport System (STS-78) mission completed the exercise protocol before, during, and after a 17-day spaceflight. The maximal voluntary contraction torque output at the onset of exercise was similar on all test days. Before spaceflight, plasma BGH increased 114–168% from pre- to postexercise. During spaceflight and after 2 days recovery at normal gravity (1 G), the BGH response to exercise was absent. After 4 days of recovery, this response was restored. Plasma concentrations of immunoassayable growth hormone were similar at all time points. The preexercise plasma immunoassayable insulin-like growth factor I (IGF-I) levels were elevated after 12 or 13 days of microgravity, and a ≈7% postexercise IGF-I increase was independent of this spaceflight effect. The suppression of the BGH response to exercise during spaceflight indicates that some minimum level of chronic neuromuscular activity and/or loading is necessary to maintain a normal exercise-induced BGH release. Moreover, these results suggest that there is a muscle afferent-pituitary axis that can modulate BGH release.

Effect of feed restriction on plasma concentration of hormones and metabolites in steers fed grass silage

2001 ◽  
Vol 81 (4) ◽  
pp. 553-561 ◽  
Author(s):  
D. R. Ouellet ◽  
J. R. Seoane ◽  
J. F. Bernier ◽  
H. Lapierre
Keyword(s):  
Growth Hormone ◽  
Stem Elongation ◽  
Average Daily Gain ◽  
Plasma Concentrations ◽  
Feed Restriction ◽  
Beef Steers ◽  
Grass Silage ◽  
Boot Stage ◽  
Igf I ◽  
Daily Gain

Plasma concentrations of hormones and metabolites were measured in growing steers to establish their relation with degree of feed restriction. Sixty medium frame beef steers (259 ± 29 kg) were divided in groups of five and fed during 3 mo either timothy (T) or bromegrass (B) harvested at stem elongation of the first cut or at boot stage of the aftermath. Forages were fed at one of three levels of intake: ad libitum (FF), 80% of FF, or 65% of FF. Plasma concentrations of growth hormone (GH), insulin, glucagon, insulin-like growth factor-1 (IGF-1), glucose and nonesterfied fatty acids (NEFA) were measured on day 1 and day 78 before the morning meal. The effect of a meal on GH, insulin, glucagon, IGF-1, glucose and NEFA concentrations was also determined in 24 steers sampled from 3 h before to 3 h after a meal. Severity of feed restriction resulted in a linear decrease (P < 0.05) of plasma glucagon (0.139, 0.130, 0.121 ± 0.005 ng mL–1) and IGF-1 (109, 98, 84 ± 7 ng mL–1). Insulin concentration tended to be affected quadratically (0.37, 0.35, 0.27 ± 0.04ng mL–1 for FF, 80% of FF and 65% of FF, respectively, P < 0.10). Ingestion of a meal resulted in a decrease (P < 0.05) of GH, NEFA and glucose, and an increase of insulin concentrations (P < 0.05). There was a positive correlation (r = 0.53, P < 0.05) between IGF-1 and average daily gain, and lipid percentage of carcasses suggesting that IGF-1 is related to growth rate and fat accumulation in growing steers. Key words: Feed restriction, growth hormone, insulin, IGF-I, metabolites, grass silage

Responses of IGF-I to endogenous increases in growth hormone after heavy-resistance exercise

1995 ◽  
Vol 79 (4) ◽  
pp. 1310-1315 ◽  
Author(s):  
W. J. Kraemer ◽  
B. A. Aguilera ◽  
M. Terada ◽  
R. U. Newton ◽  
J. M. Lynch ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Creatine Kinase ◽  
Resistance Exercise ◽  
Acute Exercise ◽  
Recovery Period ◽  
Exercise Protocol ◽  
Significant Relationships ◽  
Igf I ◽  
Heavy Resistance Exercise ◽  
And Control

The purpose of this study was to examine the effects of a heavy-resistance exercise protocol known to dramatically elevate immunoreactive growth hormone (GH) on circulating insulin-like growth factor I (IGF-I) after the exercise stimulus. Seven men (23.1 +/- 2.4 yr) volunteered to participate in this study. Each subject was asked to perform an eight-station heavy-resistance exercise protocol consisting of 3 sets of 10 repetition maximum resistances with 1-min rest between sets and exercises followed by a recovery day. In addition, a control day followed a nonexercise day to provide baseline data. Pre- and postexercise (0, 15, and 30 min) blood samples were obtained and analyzed for lactate, creatinine kinase, GH, and IGF-I. Postexercise values for lactate and GH were significantly (P < 0.05) elevated above preexercise and resting baseline values. The highest mean GH concentration after the heavy-resistance exercise protocol was 23.8 +/- 11.8 micrograms/l, observed at the immediate postexercise time point. Significant increases in creatine kinase were observed after the exercise protocol and during the recovery day. No significant relationships were observed between creatine kinase and IGF-I concentrations. No significant changes in serum IGF-I concentrations were observed with acute exercise or between the recovery and control days. Thus, these data demonstrate that a high-intensity bout of heavy-resistance exercise that increases circulating GH did not appear to affect IGF-I concentrations over a 24-h recovery period in recreationally strength-trained and healthy young men.

A novel, noninvasive transdermal fluid sampling methodology: IGF-I measurement following exercise

2011 ◽  
Vol 300 (6) ◽  
pp. R1326-R1332 ◽  
Author(s):  
D. E. Scofield ◽  
H. L. McClung ◽  
J. P. McClung ◽  
W. J. Kraemer ◽  
K. R. Rarick ◽  
...  
Keyword(s):  
Acute Exercise ◽  
Active Muscle ◽  
Acute Bout ◽  
Factor I ◽  
Exercise Condition ◽  
Plyometric Exercise ◽  
Igf I ◽  
Exercise Induced ◽  
Induced Changes ◽  
Fluid Sampling

This study tested the hypothesis that transdermal fluid (TDF) provides a more sensitive and accurate measure of exercise-induced increases in insulin-like growth factor-I (IGF-I) than serum, and that these increases are detectable proximal, but not distal, to the exercising muscle. A novel, noninvasive methodology was used to collect TDF, followed by sampling of total IGF-I (tIGF-I) and free IGF-I (fIGF-I) in TDF and serum following an acute bout of exercise. Experiment 1: eight men (23 ± 3 yrs, 79 ± 7 kg) underwent two conditions (resting and 60 min of cycling exercise at 60% V̇o2peak) in which serum and forearm TDF were collected for comparison. There were no significant changes in tIGF-I or fIGF-I in TDF obtained from the forearm or from serum following exercise ( P > 0.05); however, the proportion of fIGF-I to tIGF-I in TDF was approximately fourfold greater than that of serum ( P ≤ 0.05). These data suggest that changes in TDF IGF-I are not evident when TDF is sampled distal from the working tissue. To determine whether exercise-induced increases in local IGF-I could be detected when TDF was sampled directly over the active muscle group, we performed a second experiment. Experiment 2: fourteen subjects (22 ± 4 yr, 68 ± 11 kg) underwent an acute plyometric exercise condition consisting of 10 sets of 10 plyometric jumps with 2-min rest between sets. We observed a significant increase in TDF tIGF-I following exercise ( P ≤ 0.05) but no change in serum tIGF-I ( P > 0.05). Overall, these data suggest that TDF may provide a noninvasive means of monitoring acute exercise-induced changes in local IGF-I when sampled in proximity to exercising muscles. Moreover, our finding that the proportion of free to tIGF-I was greater in TDF than in serum suggests that changes in local IGF-I may be captured more readily using this system.

Increased secretion of insulin-like growth factor I into milk of cows treated with recombinantly derived bovine growth hormone

1989 ◽  
Vol 56 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Colin G. Prosser ◽  
Ivan R. Fleet ◽  
Anthony N. Corps
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Milk Yield ◽  
Plasma Concentrations ◽  
Significant Proportion ◽  
Bovine Growth Hormone ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

SummarySix lactating, non-pregnant Jersey cows were given subcutaneous injections of recombinantly derived bovine growth hormone for 7 d. Milk yield was increased by 4·5 kg/d on d 7, compared with the average yield of 10·7 ± 0·4 kg/d (mean ± s. e. m.) for the 7d preceding treatment. Concentrations of insulin-like growth factor I (IGF-I) in the milk increased from 0·44 ± 0·04 nmol/1 (mean ± s. e. m.) during the 7 d preceding treatment to 1·6 ± 0·2 nmol/1 on d 7 of treatment. Taking the increase in milk yield into account the total increase in the secretion of IGF-I into milk of one udder half was 6-fold. Plasma concentrations of total IGF-I rose from 15·5 + 1·3 nmol/1 (mean ± s. e. m.) on the day preceding treatment to 56·9 ± 3·6 nmol/1 (mean ± s. e. m.) on d 7 of treatment. Mammary plasma flow increased from 1·6 ± 0·09 to 2·2 ± 0·06 1/min udder half over the same time. Estimates of the amount of IGF-I that reached the mammary gland gave values of 24 and 116 nmol/min udder half before and during treatment respectively. IGF-I in milk of treated cows was associated predominantly with proteins ranging from 40000 to 150000 mol. wt, but a significant proportion (19%) of the total IGF-I was present in the free unbound form. IGF-I crosslinking studies revealed the presence in milk of one specifically labelled band at 31000 mol. wt.

Effects of growth hormone injections on ovulation rate in ewes

1990 ◽  
Vol 2 (2) ◽  
pp. 173 ◽  
Author(s):  
SR Davis ◽  
JF Smith ◽  
PD Gluckman
Keyword(s):  
Growth Hormone ◽  
Plasma Concentrations ◽  
Post Treatment ◽  
Ovulation Rate ◽  
The Other ◽  
Bovine Growth Hormone ◽  
Factor I ◽  
Igf I ◽  
Pre Treatment ◽  
Clover Pasture

Coopworth ewes were either treated with 5 mg recombinant-derived bovine growth hormone per day for each day of the oestrous cycle or were untreated. Ovulation rates at the pre-treatment, post-treatment and a subsequent oestrus were determined by endoscopy. These were 1.34, 1.51, 1.38 for the treated ewes and 1.32, 1.43, 1.39 for the control ewes. The ovulation rate post-treatment was significantly higher than for the other two cycles in the treated ewes but it was not significantly different from the post-treatment value of the control ewes. Plasma concentrations of insulin-like growth factor-I (IGF-I) were elevated during treatment (90-130 nmol L-1) compared with concentrations of 25-50 nmol L-1 in the control ewes. No relationship was found between plasma IGF-I concentration and ovulation rate. Injection of ewes grazing ryegrass/white clover pasture with bovine growth hormone did not result in increased ovulation rate.

Stimulation of the renin-angiotensin system by growth hormone in Lewis dwarf rats

1993 ◽  
Vol 265 (2) ◽  
pp. E332-E339 ◽  
Author(s):  
B. Wyse ◽  
M. Waters ◽  
C. Sernia
Keyword(s):  
Growth Hormone ◽  
Plasma Concentrations ◽  
Renin Angiotensin System ◽  
Plasma Renin ◽  
Angiotensin Ii Receptor ◽  
Gh Treatment ◽  
Angiotensin System ◽  
Lewis Rats ◽  
Renin Angiotensin ◽  
Igf I

A genetically growth hormone (GH)-deficient strain of Lewis rats was used to test the hypothesis that the actions of GH on electrolyte and fluid homeostasis are mediated by the renin-angiotensin-aldosterone system (RAAS). Dwarf rats injected with recombinant bGH (2 mg.kg-1 x day-1) for 7 days (group GH1+) and 28 days (group GH4+), respectively, were compared with saline-injected dwarf (group GH-) and normal (group N) Lewis rats. GH decreased Na+ excretion and increased renal glomerular filtration rate in dwarf rats. The dietary intake and plasma concentrations of Na+ and K+ remained unchanged. GH increased plasma insulin-like growth factor I (IGF-I) concentrations in dwarf rats (GH - = 109 +/- 9, GH1+ = 184 +/- 5, GH4+ = 189 +/- 28, N = 477 +/- 29 ng/ml plasma). Plasma angiotensinogen increased towards the levels found in normal Lewis rats (GH- = 859 +/- 38, GH1+ = 906 +/- 18, GH4+ = 1,027 +/- 19, N = 1497 +/- 80 ng angiotensin I/ml plasma); plasma renin activity increased above that of the normal Lewis (GH- = 10.2 +/- 0.6, GH1+ = 11.7 +/- 0.7, GH4+ = 16.7 +/- 2.4, N = 10.6 +/- 0.8 ng angiotensin I.ml plasma-1 x h-1). Plasma aldosterone, corticosterone, and triodothyronine concentrations were unchanged by GH treatment. Angiotensin II receptor densities in GH- rats (liver = 356 +/- 23, kidney = 228 +/- 28, adrenal = 478 +/- 58 fmol/mg protein) were upregulated by GH (GH4+ rats; liver = 573 +/- 27, kidney = 360 +/- 86, adrenal = 721 +/- 78 fmol/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)

Nutrition and colostrum production in sheep. 1. Metabolic and hormonal responses to a high-energy supplement in the final stages of pregnancy

2004 ◽  
Vol 16 (6) ◽  
pp. 633 ◽  
Author(s):  
G. E. Banchero ◽  
G. Quintans ◽  
G. B. Martin ◽  
D. R. Lindsay ◽  
J. T. B. Milton
Keyword(s):  
Growth Hormone ◽  
Plasma Concentrations ◽  
High Energy ◽  
Hormonal Responses ◽  
Energy Supplement ◽  
Igf I

We tested the hypothesis that supplementation with cracked maize during the last week of pregnancy would provide ewes with a substrate for glucose and enhance the synthesis of lactose and, consequently, their production of colostrum. Thirty single- and 30 twin-bearing ewes were fed lucerne hay and half of each group was supplemented daily with 0.75 kg per head cracked maize during the last week of pregnancy. Colostrum production and the endocrine patterns in the animals were investigated. Supplementation with maize more than doubled the mass of colostrum available at birth in unsupplemented ewes: 339 v. 145 g in single-bearing ewes and 536 v. 197 g in twin-bearing ewes (P < 0.001). The total colostrum produced in the 10 h after birth was also significantly increased by supplementation: 730 v. 475 g in single-bearing ewes and 1259 v. 631 g in twin-bearing ewes (P < 0.01). The colostrum in the supplemented ewes was also more liquid with a viscosity score of 5.8 compared with 5.7 and 4.5 in unsupplemented single- and twin-bearing ewes (P < 0.01). Supplemented ewes had higher concentrations of lactose in their colostrum at parturition (2.6% v. 1.8% in single-bearing ewes and 2.5% v. 1.4% in twin-bearing ewes; P < 0.01). The plasma concentrations of progesterone and growth hormone in supplemented ewes were lower, whereas those of IGF-I and insulin were higher, all consistent with a higher capacity to produce colostrum. It is concluded that a high-energy supplement, like maize, fed to ewes in the last week of gestation increases their capacity to produce colostrum for their lambs, particularly for ewes bearing twins.

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