Limits...
Repetitive stimulation of the pituitary with growth-hormone-releasing hormone alters the proportion of 22 and 20 kilodalton human-growth hormone released.

Webb EA, Pringle PJ, Robinson IC, Hindmarsh PC - Int J Pediatr Endocrinol (2010)

Bottom Line: Results.Half-life of 20 and 22 K-hGH were not significantly different (P = .55).Conclusions.

View Article: PubMed Central - PubMed

Affiliation: Developmental Endocrinology Research Group, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.

ABSTRACT
Background/Aims. 20 Kilodalton-hGH (20 K-hGH) is the second most abundant pituitary GH variant after 22 K-hGH. In the steady state the proportion of 20 : 22 K-hGH appears constant; does this proportion change with repetitive somatotroph stimulation? Methods. Forty adult males were randomised to receive a GHRH(1-29)NH(2) bolus (0.5 mug/kg (n = 20) or 1.0 mug/kg (n = 20)), preceded or followed by a saline bolus, 1 week apart. Four to six weeks later, 10 subjects received 0.5 mug/kg GHRH(1-29)NH(2) at 0, 60, 120, and 180 minutes. Clearance rate of 22 and 20 K-hGH was measured in 10 subjects. Results. Total amount/proportion of 22 K-hGH/20 K-hGH secreted was similar for both GHRH(1-29)NH(2) doses. Repetitive stimulation reduced the amount of 22 K-hGH released whereas the amount of 20 K-hGH did not change significantly leading to an increase in the proportion of 20 K-hGH (P = .05). Half-life of 20 and 22 K-hGH were not significantly different (P = .55). Conclusions. Repetitive stimulation of the somatotroph may alter the proportion of GH variant released.

No MeSH data available.


Percentage Serum 20 kDa Growth-Hormone concentration after repeat bolus intravenous administration of 0.5 μg GHRH(1–29)NH2. Data shown as mean and SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2902052&req=5

fig2: Percentage Serum 20 kDa Growth-Hormone concentration after repeat bolus intravenous administration of 0.5 μg GHRH(1–29)NH2. Data shown as mean and SEM.

Mentions: We tested the effects of the GHRH(1–29)NH2 dose administered as a single and then further bolus injections and determined, the amounts and proportion of 20 K-hGH released. With more frequent stimulation the amount of 22 K-hGH released decreased significantly (One way ANOVA F = 16.4; P < .001) whereas the amount of 20 K-hGH did not change significantly, resulting in a net increase in percentage of 20 K-hGH present (F = 3.10; P = .05) (Figure 1, Table 2 and Figure 2). By multiple regression analysis (R = 0.29; P = .04) the intensity of response to GHRH(1–29)NH2 was the major determinant of the percentage of 20 K-hGH present (B = 3.89, P = .02) with a much lesser contribution from the total amount of hGH released (B = 0.11, P = .11).


Repetitive stimulation of the pituitary with growth-hormone-releasing hormone alters the proportion of 22 and 20 kilodalton human-growth hormone released.

Webb EA, Pringle PJ, Robinson IC, Hindmarsh PC - Int J Pediatr Endocrinol (2010)

Percentage Serum 20 kDa Growth-Hormone concentration after repeat bolus intravenous administration of 0.5 μg GHRH(1–29)NH2. Data shown as mean and SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2902052&req=5

fig2: Percentage Serum 20 kDa Growth-Hormone concentration after repeat bolus intravenous administration of 0.5 μg GHRH(1–29)NH2. Data shown as mean and SEM.
Mentions: We tested the effects of the GHRH(1–29)NH2 dose administered as a single and then further bolus injections and determined, the amounts and proportion of 20 K-hGH released. With more frequent stimulation the amount of 22 K-hGH released decreased significantly (One way ANOVA F = 16.4; P < .001) whereas the amount of 20 K-hGH did not change significantly, resulting in a net increase in percentage of 20 K-hGH present (F = 3.10; P = .05) (Figure 1, Table 2 and Figure 2). By multiple regression analysis (R = 0.29; P = .04) the intensity of response to GHRH(1–29)NH2 was the major determinant of the percentage of 20 K-hGH present (B = 3.89, P = .02) with a much lesser contribution from the total amount of hGH released (B = 0.11, P = .11).

Bottom Line: Results.Half-life of 20 and 22 K-hGH were not significantly different (P = .55).Conclusions.

View Article: PubMed Central - PubMed

Affiliation: Developmental Endocrinology Research Group, Institute of Child Health, University College London, 30 Guilford Street, London WC1N 1EH, UK.

ABSTRACT
Background/Aims. 20 Kilodalton-hGH (20 K-hGH) is the second most abundant pituitary GH variant after 22 K-hGH. In the steady state the proportion of 20 : 22 K-hGH appears constant; does this proportion change with repetitive somatotroph stimulation? Methods. Forty adult males were randomised to receive a GHRH(1-29)NH(2) bolus (0.5 mug/kg (n = 20) or 1.0 mug/kg (n = 20)), preceded or followed by a saline bolus, 1 week apart. Four to six weeks later, 10 subjects received 0.5 mug/kg GHRH(1-29)NH(2) at 0, 60, 120, and 180 minutes. Clearance rate of 22 and 20 K-hGH was measured in 10 subjects. Results. Total amount/proportion of 22 K-hGH/20 K-hGH secreted was similar for both GHRH(1-29)NH(2) doses. Repetitive stimulation reduced the amount of 22 K-hGH released whereas the amount of 20 K-hGH did not change significantly leading to an increase in the proportion of 20 K-hGH (P = .05). Half-life of 20 and 22 K-hGH were not significantly different (P = .55). Conclusions. Repetitive stimulation of the somatotroph may alter the proportion of GH variant released.

No MeSH data available.