Hexarelin · research summary

Enhanced Pulsatile Growth Hormone Secretion and Altered Metabolic Hormones by in Vivo Hexarelin Treatment in Streptozotocin-Induced Diabetic Rats.

International journal of molecular sciences · 2018. Summary drawn from the study's full text. Each statement is followed by the exact sentence it comes from. This is a research summary, not medical advice.

Study type

Animal study investigating the effect of hexarelin on growth hormone secretion in streptozotocin-induced diabetic rats
“Thus, we aim to investigate the effect of hexarelin, a synthetic GH secretagogue (GHS), on GH secretion in streptozotocin (STZ, 65 mg/kg)-induced diabetic rats.”

Subjects

Male Wistar rats
“Male Wistar rats (150–200 g, 6 weeks of age) were used in the study.”

Sample size

16 rats per group for GH secretion analysis, 8 rats per group for GTT/ITT, and 6 rats per group for IGF-1/FFA analysis
“n = 16, data are shown as the mean ± SEM.”

Duration

Two weeks of hexarelin treatment following four weeks of diabetes induction
“Daily hexarelin (100 μg/kg) treatment was performed for two weeks in four-week-long STZ-diabetic and vehicle control rats.”

Reported findings

Hexarelin treatment significantly increased total, pulsatile, and basal GH secretion in STZ-diabetic rats, but did not significantly increase the mass of GH secreted per burst.
“Hex treatment recovered GH release in STZ-diabetic animals significantly in total (826 ± 197 vs. 356 ± 75.3 ng/mL per 6 h, p < 0.05), pulsatile (524 ± 44.6 vs. 192 ± 24.6 ng/mL per 6 h, p < 0.001), and basal (159 ± 36.6 vs. 19.2 ± 9.67 ng/mL per 6 h, p < 0.01), but not in the mass of GH secreted per burst (178 ± 28.9 vs. 118 ± 23.0 ng/mL, p = 0.14) (Figure 2).”
Hexarelin treatment normalized elevated fasting free fatty acid levels in STZ-diabetic rats.
“In addition, hexarelin-treated STZ-rats showed a significant decrease in fasting level FFAs, whereas suppression of fasting level for IGF-1 was maintained.”
Hexarelin treatment did not restore plasma IGF-1 levels in STZ-diabetic rats.
“Hex treatment normalized the elevated FFA levels, but did not change plasma IGF-1 levels, indicating that circulating FFAs might be transported into fat tissue, facilitated by Hex.”

Limitations stated by the authors

The treatment duration may have been insufficient to alter plasma IGF-1 levels, and the mechanism by which hexarelin increases insulin sensitivity is not fully established.
“The treatment time in this experiment may not have be long enough to alter plasma IGF-1 levels, as previous studies used longer treatment times.”

Source: PubMed 30297647 · DOI 10.3390/ijms19103067 · all study summaries

Reported findings

Hexarelin treatment significantly increased total, pulsatile, and basal GH secretion in STZ-diabetic rats, but did not significantly increase the mass of GH secreted per burst.

“Hex treatment recovered GH release in STZ-diabetic animals significantly in total (826 ± 197 vs. 356 ± 75.3 ng/mL per 6 h, p < 0.05), pulsatile (524 ± 44.6 vs. 192 ± 24.6 ng/mL per 6 h, p < 0.001), and basal (159 ± 36.6 vs. 19.2 ± 9.67 ng/mL per 6 h, p < 0.01), but not in the mass of GH secreted per burst (178 ± 28.9 vs. 118 ± 23.0 ng/mL, p = 0.14) (Figure 2).”

Hexarelin treatment normalized elevated fasting free fatty acid levels in STZ-diabetic rats.

“In addition, hexarelin-treated STZ-rats showed a significant decrease in fasting level FFAs, whereas suppression of fasting level for IGF-1 was maintained.”

Hexarelin treatment did not restore plasma IGF-1 levels in STZ-diabetic rats.

“Hex treatment normalized the elevated FFA levels, but did not change plasma IGF-1 levels, indicating that circulating FFAs might be transported into fat tissue, facilitated by Hex.”

Limitations stated by the authors

The treatment duration may have been insufficient to alter plasma IGF-1 levels, and the mechanism by which hexarelin increases insulin sensitivity is not fully established.

“The treatment time in this experiment may not have be long enough to alter plasma IGF-1 levels, as previous studies used longer treatment times.”