Synergism and diurnal variations of human growth hormone-releasing factor (1-29)NH2 and thyrotropin-releasing factor on growth hormone release in dairy calves.
Lapierre. H H; Petitclerc. D D; Pelletier. G G; Dubreuil. P P; Morisset. J J; Gaudreau. P P; Couture. Y Y; Brazeau. P P
Key Findings
- Sermorelin‑like peptide alone raised GH modestly (~50 ng/ml peak).
- Combining it with thyrotropin‑releasing factor raised GH peaks up to ~226 ng/ml during daylight.
- GH responses were far lower at night regardless of the combination.
- Light exposure (day‑night cycle) strongly modulated the hormone surge.
Practical Outcomes
- For biohackers, take sermorelin in the morning or early afternoon (when it’s light) to get the biggest GH lift, and consider adding a TRH‑type peptide if you want an extra boost. Night‑time dosing is far less effective for GH release.
Summary
In a calf study, giving the growth‑hormone‑releasing peptide (similar to sermorelin) together with a thyroid‑releasing peptide caused a big boost in growth‑hormone spikes, but only when the shots were taken during the light part of the day. When given at night, the boost was much smaller. This shows that timing and possibly pairing with a TRH‑type peptide matter for getting the strongest GH response.
Abstract
Sixteen male Holstein calves averaging 168 kg body weight (BW) were used to determine the effects of human growth hormone-releasing factor (1-29)NH2 (hGRF (1-29)NH2; .22 micrograms/kg BW), thyrotropin-releasing factor (TRF; .165 micrograms/kg BW) or hGRF (1-29)NH2 plus TRF (.22 and .165 micrograms/kg BW, respectively) on growth hormone (GH) release in animals exposed to 16 hr of light (L): 8 hr of dark (D) (lights on at 0100 hr) and hGRF plus TRF (.22 and .165 micrograms/kg BW, respectively) in animals exposed to 8L:16D (lights on at 0900 hr). For each treatment, times of iv injection were 0400, 1000, 1600 and 2200 hr. In animals exposed to 16L:8D, average GH peaks reached after hGRF (1-29)NH2 or TRF injections were 49.7 and 32.0 ng/ml while the area under the GH response curve (AUC) were 1247 and 1019 ng/ml.min, respectively. There was no significant effect of times of injection on GH release following the separate injection of hGRF(1-29)NH2 or TRF. In animals exposed to 16L:8D, GH peaks and AUC after hGRF plus TRF injections were 226.4, 189.2 and 116.8 ng/ml, and 4340, 3660 and 2415 ng/ml.min at 0400, 1000 and 1600 hr (lights on), respectively but only 42.3 ng/ml and 1692 ng/ml.min at 2200 hr (lights off). In animals exposed to 8L:16D, GH levels and AUC after hGRF plus TRF injections reached 177.5 and 180.5 ng/ml, and 2759 and 3704 ng/ml.min at 1000 and 1600 hr (lights on) but only 84.0 and 72.7 ng/ml, and 1544 and 1501 ng/ml.min at 0400 and 2200 hr (lights off), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Study Information
pubmed
1987
1987-10-01T00:00:00.000Z
10.1016/0739-7240(87)90017-8
12
32