Tissue and plasma distribution of exogenous growth hormone-releasing factor analogue (GRF1-29NH2) after intravenous, subcutaneous and intraperitoneal injection in the rat.
Fernandez-Gonzalez. M A MA; Barrios. V V; Sancho. J I JI; Arilla. E E; Carmena. M J MJ; Tresguerres. J A JA; Prieto. J C JC
Key Findings
- IV injection causes a rapid spike in blood levels; SC and IP injections produce a slower, more prolonged increase.
- The peptide is quickly degraded in the bloodstream.
- Gut tissues (antrum, duodenum, ileum) take up the peptide via VIP receptors, while the pituitary shows specific uptake but the thyroid and parathyroid do not.
Practical Outcomes
- For self‑experimenters, sermorelin has a short half‑life, so frequent dosing or a slow‑release method may be needed for sustained effects. Subcutaneous injection may give a gentler, longer‑lasting rise in hormone levels compared to IV. The peptide appears to act mainly on the pituitary and gut, with little direct impact on thyroid or parathyroid function.
Summary
When you inject the growth‑hormone‑releasing factor analogue (sermorelin) into rats, it shows up in the blood quickly if given IV, but more slowly if given under the skin or into the belly. The peptide breaks down fast, and it mainly ends up in the gut and the pituitary gland, not in the thyroid or parathyroid.
Abstract
1. The administration of 125I-labelled growth hormone-releasing factor (GRF) analogue 1-29NH2 by intravenous, subcutaneous or intraperitoneal injection to rats leads to rapid (i.v.) or slow (s.c. and i.p.) increases in plasma radioactivity followed by extensive breakdown of the peptide. 2. Tissues possessing GRF-like immunoreactivity such as gastric antrum (but not fundus), duodenum and ileum showed in vitro specific uptake of 125I-GRF probably mediated by vasoactive intestinal peptide (VIP) receptors. 3. Pituitary (the primary target organ for GRF) but neither thyroid nor parathyroid exhibited specific uptake of 125I-GRF.
Study Information
pubmed
1987
10.1016/0306-3623(87)90079-6
3
16