Growth hormone response to human pancreatic growth hormone releasing factor in cattle.

Johke, Tetsu; Hodate, Koichi; Ohashi, Satoshi; Shiraki, Masaru; Sawano, Shinji

doi:10.1507/endocrj1954.31.55

Cited by 30 publications

(16 citation statements)

References 15 publications

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“…On all the days of blood sampling a peak of endogenous GH was always registered, suggesting chronic GRF injections for 3 months did not cause any refractoriness of endogenous GH release. The GRF-induced GH response was also found to decrease with age in rats (Sonntag et al 1983, Ceda et al 1986, Cuttler et al 1986 and cattle (Johke et al 1984), and this decrease could be due to a decrease in sensitivity of somatotrophs to GRF with ageing (Ceda et al 1986), an increase in sensitivity of somatotrophs to somatostatin with ageing (Cuttler et al 1986) and/or to an age-related accumulation of somatostatin in somatotrophs (Brazeau et al 1986). …”

Section: Plasma Gh Changes Associated With Grf Administrationmentioning

confidence: 98%

Effects of long-term GH-releasing factor administration on patterns of GH and LH secretion in growing female buffaloes (Bubalus bubalis)

Mondal¹,

Prakash²

2004

Reproduction

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To investigate the effects of long-term GH-releasing factor (GRF) administration on the patterns of GH and LH secretion in growing female Murrah buffalo (Bubalus bubalis) calves, 12 buffaloes of 6-8 months of age were divided into two groups (treatment and control groups) of six each in such a way that average body weight between the groups did not differ significantly (P > 0.05). Both the groups were administered i.v. with either synthetic bovine GRF (bGRF(1 -44)-NH 2 ) at 10 mg/100 kg body weight (treatment group) or an equal volume of normal saline (control group) at intervals of 15 days until 18 injections had been completed (9 months). Blood samples collected prior to and after the first and last injection of GRF at 260, 245, 230, 215, 2 10, 2 5 min and 1 5, 1 10, 1 15, 1 30 min, and thereafter at intervals of 15 min up to 8 h post-injection, were assayed for plasma GH and LH. Plasma progesterone was also estimated in twice-a-week samples to assess whether either group had begun ovarian cyclicity. The body weight of all animals was recorded twice a week. In all animals, a peak of GH was recorded within 5-20 min and 5-30 min after the first and last GRF injections and post-injection mean values for plasma GH were significantly (P < 0.01) higher compared with the control group of animals. Although peak GH values after the first and last GRF injection did not differ (P > 0.05), GH levels were maintained at a higher level for a longer time after the last GRF injection compared with the first (240 vs 150 min). The area under the GH response curve after the last GRF injection was found to be significantly (P < 0.01) higher than after the first injection (9344 6 199.7 vs 7763 6 112.4 ng/ml 3 min). The mean post-injection plasma LH levels of the treatment group were significantly (P < 0.01) higher after both the first and last GRF injections than in the control group of animals. Interestingly, compared with the first GRF injection, the preinjection plasma LH level was found to be significantly higher (P < 0.01) at the last injection. The plasma LH concentrations around the last injection of GRF were significantly higher (P < 0.01) than those recorded at the time of the first injection in treated buffaloes. Correspondingly, the plasma LH concentrations in controls were also higher (P < 0.01) around the last injection of GRF vis-à-vis the first injection. The hormone concentration exhibited a higher pulsatility with greater amplitude after the last injection as compared with that recorded after the first injection. Although pulses of LH were also recorded in controls following the last injection, these were fewer and of lower magnitude than those seen in treated animals. No animal from either group reached puberty. GRF-treated buffaloes attained higher (P < 0.001) body weight than the controls. In conclusion, long-term administration of GRF induces and even enhances GH release without any sign of refractoriness, and significantly increases plasma LH also. Hence, long-term treatment with GRF may be used to mai...

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Section: Plasma Gh Changes Associated With Grf Administrationmentioning

confidence: 98%

Effects of long-term GH-releasing factor administration on patterns of GH and LH secretion in growing female buffaloes (Bubalus bubalis)

Mondal¹,

Prakash²

2004

Reproduction

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“…These results demonstrated that both TRH and GRF could stimulate GH secretion in cattle, but nobody had studied the influence of these peptides on GH and IGF, release during the postnatal period in calves. It has been demonstrated that plasma GH response to GRF 1-44 in bovines decreases with age : the response observed in 4-month old calves was more intense than that measured in heifers or cows (Johke et al, 1984). In these animals as well as in our calves, GRF induced a marked rise in plasma GH concentration at all the doses studied (20 to 200 nmoles.kg-1 of body wt), and this elevation occurred within 10 min after injection (Johke et a/., 1984) (figs.…”

Section: Introductionmentioning

confidence: 94%

“…In these 10-day old animals, GRF GRF has been used to stimulate GH secretion in farm animals (Johke et al, 1984 ;McCutcheon et al, 1984 ;Moseley et al, 1984 ;Hodate, Johke and Ohaschi, 1985) so as to increase milk yield in cows (Enright et al, 1985 ; and ewes (Hart et al, 1985). Similarly, when GRF 1-29 was injected intravenously (0.2 nmoles.kg-' of body wt) six times per day for 10 days, cow milk yield increased by 16.1 % .…”

Section: Introductionmentioning

confidence: 99%

Plasma somatotropin and somatomedin C concentrations following GRF or TRH injections in newborn calves

Coxam¹,

Davicco²,

Opmeer³

et al. 1987

Reprod. Nutr. Dévelop.

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“…On the other hand, exogenous human growth hormone-releasing factor (hGRF) specifically stimulates GH release in cattle (Johke et al, 1984;Moseley et al, 1984). Furthermore, it has been reported that exogenous hGRF (Enright et al, 1986;Pelletier et al, 1987;Lapierre et al, 1988) or bovine GRF (bGRF; Enright et al, 1988) increased milk production in dairy cows, and these increases in milk production are thought to be mediated by increased endogenous GH via hGRF or bGRF.…”

mentioning

confidence: 99%

Plasma Growth Hormone, Insulin-Like Growth Factor-I, and Milk Production Responses to Exogenous Human Growth Hormone-Releasing Factor Analogs in Dairy Cows.

et al. 1990

Self Cite

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Responses of plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I), and milk production to subcutaneous (sc) injection(s) of two synthetic human growth hormone-releasing factor (hGRF) analogs were studied in dairy cows. Two mg of each hGRF analog dissolved in 5ml saline per cow were injected into the shoulder area of each experimental animal, and jugular venous blood samples were collected via an indwelling catheter or by venipuncture. Plasma GH and IGF-I concentrations were measured by radioimmnoassay methods.In dry cows, the mean concentration of plasma GH after a single sc injection of hGRF analogs rose to 22.0-28.3ng/ml at about 5h from 1.4-1.7ng/ml at 0h (just before injection), and returned to the level before injection after 10-12h. On the other hand, the plasma IGF-I began to increase after a lag of 4-6h following a single injection of hGRF analogs, and reached maximum values of 71.1-89.4ng/ml at 20h from 43.7-46.4ng/ml at 0h. The IGF-I concentration at 24h after a single injection of hGRF analogs was still higher than the value for the dry cows given saline.In lactating cows, the plasma concentration of GH at 2h after daily sc injections of hGRF analogs during 14 consecutive days (an injection period) was higher than those for the lactating cows which received saline. Also, during the injection period, the concentration of IGF-I was higher in the lactating cows which received hGRF analog injections than in the cows which received saline injections. During the last 7 days of the injection period, the administration of hGRF analogs increased the mean milk yield by 11-19% in comparison with those for the saline in jected cows. A positive correlation was observed between the mean plasma IGF-I concentration and the mean milk yield in the lactating cows treated with hGRF analogs throughout the injection and a postinjection (11 consecutive days after cessation of hGRF analog injection) periods.The results demonstrate that a single sc injection of hGRF analogs stimulates both GH release and the circulating level of IGF-I in dry cows, and that daily sc injections of hGRF analogs over 14 days enhance milk production, and plasma GH and IGF-I levels in lactating cows.

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Growth hormone response to human pancreatic growth hormone releasing factor in cattle.

Abstract: The

Cited by 30 publications

References 15 publications

Effects of long-term GH-releasing factor administration on patterns of GH and LH secretion in growing female buffaloes (Bubalus bubalis)

Effects of long-term GH-releasing factor administration on patterns of GH and LH secretion in growing female buffaloes (Bubalus bubalis)

Plasma somatotropin and somatomedin C concentrations following GRF or TRH injections in newborn calves

Plasma Growth Hormone, Insulin-Like Growth Factor-I, and Milk Production Responses to Exogenous Human Growth Hormone-Releasing Factor Analogs in Dairy Cows.

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