Abstract
Objective We investigated direct effects of a therapeutic growth hormone dose on lipolysis,
glucose and amino acid metabolism.
Methods This crossover microdialysis trial involved six healthy male volunteers receiving
single subcutaneous injections of both growth hormone (0.035 mg/kg) and placebo (0.9%
sodium chloride). The investigation comprised three test days with standard diet.
The first day served for adaptation, the second and third one for determining study
data during 9 night hours with or without growth hormone. Abdominal subcutaneous microdialysate
and blood were continuously collected and forwarded to a separate room next door where
hourly taken samples were centrifuged and frozen until analysed.
Results Growth hormone achieved the peak serum level after 3 h followed by a plateau-like
course for the next 6 h. Glycerol in microdialysate started to rise 2 h following
growth hormone injection achieving significance compared to placebo after 9 h (P<0.05). Serum glycerol increased 4 h after growth hormone administration achieving
significance after 6 h (P<0.05). Glucose and amino acid concentrations showed neither in microdialysate nor
in serum significant differences between growth hormone and placebo. Serum values
of insulin and C-peptide revealed no significant difference between growth hormone
and placebo.
Summary and Conclusion As the result of a high single subcutaneous dose of GH, persistent lipolysis can
be shown in continuously collected microdialysate and blood, but no indication for
gluconeogenesis or protein anabolism.
Key words
growth hormone - metabolic effects - pharmacokinetics - microdialysis - glycerol
