Plasma Levels of Prolactin, Growth Hormone, and Insulin in Sheep Following the Infusion of Arginine, Leucine and Phenylalanine

Davis, Steven

doi:10.1210/endo-91-2-549

Cited by 108 publications

(48 citation statements)

References 16 publications

(25 reference statements)

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“…&horbar; The increase in immunoreactive plasma insulin with BW is similar to the increased blood insulin level observed in cattle during the finishing period (lrvin and Trenkle, 1971 ;Trenkle and Topel, 1978) and in growing sheep (John and Bergen, 1976 (Freeman, Karoly and Adelman, 1973 ;Kelly et al, 1974 ;Olefsky and Reaven, 1975 ;Runyan et al, 1979 (Bassett, 1975 ;Trenkle, 1978 ;Davis, 1972 ;Oldham, Hart and Bines, 1978). Alternatively, insulin response to 0 cell stimuli could have been decreased (Atinmo et al, 1978 ;Turner and Bryant, 1976 Bergen, 1976) and non-ruminants (Edozien et al, 1978 ;Kabadi, Eisenstein and Strack, 1976), could also be caused by the energy restriction accompanying nitrogen restriction because the former is known to lower plasma insulin level (Grizard et al, 1979 (Wirth et al, 1980).…”

Section: Introductionsupporting

confidence: 53%

Plasma insulin and insulin kinetics in growing sheep. Influence of age and diet

Grizard¹,

Szczygiel²

1983

Reprod. Nutr. Dévelop.

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Section: Introductionsupporting

confidence: 53%

Plasma insulin and insulin kinetics in growing sheep. Influence of age and diet

Grizard¹,

Szczygiel²

1983

Reprod. Nutr. Dévelop.

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“…For the amounts of amino acid infused, the effect of L-tryptophan also appeared to be relatively limited to this amino acid, since the infusion of 17 other amino acids in equivalent concentration failed to elicit increased rates of prolactin secretion. Recently, it has been reported that infusion of much larger amounts of arginine, leucine, and phenylalanine (0.2-0.5 g/kg) into the carotid artery of the ewe induced significant increases in prolactin secretion (14), and it is possible that much larger amounts of other amino acids could cause significant increases in prolactin secretion in the human. The possibility should also be recognized that the activity of an individual amino acid may have been ob- scured by other amino acids in the infused mixtures, and that further analysis may reveal intrinsic prolactinreleasing activity, although of lesser degree than that of L-tryptophan, in other amino acids.…”

Section: Discussionmentioning

confidence: 99%

Stimulation of Human Prolactin Secretion by Intravenous Infusion of L-Tryptophan

MacIndoe¹,

Turkington²

1973

J. Clin. Invest.

196

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A B S T R A C T Previous studiesThese results support the concept that the effect of L-tryptophan on the secretion of human prolactin is mediated through its conversion to serotonin and are consistent with reported experimental observations that serotonin may participate in the reciprocal regulation of prolactin and gonadotropins. INTRODUCTIONRecent studies on human prolactin have indicated the primary importance of hypothalamic mechanisms in the regulation of secretion of this hormone by the pituitary (1-3). A large body of experimental observations in animals and of pharmacological studies in the human has indicated the presence of catecholaminergic mechanisms in the hypothalamic regulation of prolactin secretion. In these studies we report an additional substance that can reciprocally regulate the secretion of prolactin and gonadotropins, the amino acid L-tryptophan. Effects observed with the intravenous infusion of this amino acid appear to relate to the presence of a serotonergic pathway mediating neuroendocrine regulation of prolactin secretion (4, 5) and provide an additional means of probing the human hypothalamic-pituitary axis.

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“…Arginine has been shown to elevate ST levels in sheep (40), cows (41) and pigs (42). Since GRFi cows did not respond to arginine, it would seem that the mechanism of action of arginine-induced ST secretion involves release of hypothalamic GRF.…”

Section: Discussionmentioning

confidence: 99%

Effect of active immunization against growth hormone releasing factor on concentrations of somatotropin and insulin-like growth factor I in lactating beef cows

Moore

Armstrong

Harvey

et al. 1992

Domestic Animal Endocrinology

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Two experiments were conducted to determine the effects of immunoneutralization of growth hormone-releasing factor [GRF(1-29)-NH 2 ] on concentrations of somatotropin (ST) and insulin-like growth factor I (IGF-I) in lactating beef cows. In Experiment 1, mUltiparous Hereford cows were immunized against 2 mg GRF(l-29)-(GlY)4-Cys-NH2 conjugated to human serum albumin (GRFi, n=3) or 2 mg human serum albumin (HSAi, n=3) at 52 ± 1 d prior to parturition. Boosters (1 mg) were administered on days 12,40 and 114 postpartum (pp). Serum samples were collected at IS-min intervals for 5 hr on days 18,46 and 120 pp, followed by administration CIV) of an opioid agonist (FK33-824; 10 J..lg/kg) and an antagonist (naloxone; .5 mg/kg) at hours 5 and 7, respectively. A GRF analog ([desamino-Tyrl, D-Ala 2 , Ala l5 ] GRF (l-29)-NH 2 ; 3.5 ~lkg) and arginine (.5 glkg) were administered at hour 10 on days 47 and 121, respectively. Percentage binding of [ 125 I]GRF (1:100 dilution of serum) 28 d after primary immunization was greater in GRFi (14.3 ± 4.9) than in HSAi (.7 ± .3) cows. Binding increased to 29.3 ± 6.5% after first booster in GRFi cows. Episodic release of ST was abolished by immunization against GRF; concentration and frequency of release of ST were lower (P<.05) in GRFi than in HSAi cows on all days pp. Concentrations of IGF-I were lower in GRFi than in HSAi cows throughout lactation. Serum ST failed to increase following FK33-824 or arginine in GRFi; however, ST increased after both compounds in HSAi cows. Concentrations of ST following GRF-analog were greater (P<.05) in HSAi than in GRFi cows. Experiment 2 was con ducted to determine if a lower dose of antigen and a single booster would be sufficient to lower ST and IGF-I in lactating cows. Multiparous Hereford and Angus cows were assigned to GRFi (n=6) or HSAi (n=6). Primary (1.2 mg) and booster (.5 mg) immunizations were administered -14 and 8 d from calving, respectively. Cows were restricted to 60% of recommended intake of energy dur ing lactation in order to elevate concentrations of ST. Serum samples were collected at IS-min in tervals for 6 hr on days 26, 50, 73, 90 and 109 pp. Two of six GRFi cows had binding less than 10% (1 : 1 ,000 dilution of serum) and were omitted from further analyses. Percentage binding at a I: 1,000 dilution was greater in GRFi (17.0 ± 4.7) than in HSAi (1.4 ± .4) cows at 89 d pp. Consequently, frequency of release, and concentration of ST and IGF-I were lower (P < .05) in GRFi than in HSAi cows. Concentrations of ST increased following FK33-824 in HSAi, but not in GRFi cows. Across experiments, interval from calving to ovulation (estimated from weekly progesterone concentrations) was greater in HSAi than in GRFi cows. In conclusion, gestating-lactating beef cows were effec , tively immunized against GRF as evidenced by antibody binding of [ 125 I]GRF, absence of pulsatile release of ST, low concentrations of ST and IGF-I and failure of ST to increase after IV opioid ago nist or arginine.

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Plasma Levels of Prolactin, Growth Hormone, and Insulin in Sheep Following the Infusion of Arginine, Leucine and Phenylalanine

Cited by 108 publications

References 16 publications

Plasma insulin and insulin kinetics in growing sheep. Influence of age and diet

Plasma insulin and insulin kinetics in growing sheep. Influence of age and diet

Stimulation of Human Prolactin Secretion by Intravenous Infusion of L-Tryptophan

Effect of active immunization against growth hormone releasing factor on concentrations of somatotropin and insulin-like growth factor I in lactating beef cows

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