We all need growth hormone – but in the right amounts
Growth hormone is a small soluble protein made in the pituitary gland in the brain and released into the bloodstream. Like insulin and other peptide hormones, it works by triggering a ‘second messenger’, which is released inside a cell when the hormone binds to a receptor on the outside of the cell membrane. Steroid hormones are smaller, fat-soluble molecules that can pass through cell membranes and usually transmit their message directly.
Growth hormone stimulates cell division in tissues sensitive to it. Most obviously, it promotes bone growth, and too little or too much of it leads to extremes of stature. Children who don’t make enough growth hormone can be given more until they reach an acceptable height. Like insulin, growth hormone has many other metabolic effects. Both of these hormones are now made by genetically engineered bacteria.
Humans naturally produce less growth hormone as they age. Some people think growth hormone can delay ageing, and some anti-ageing products such as face creams now include growth hormone. Some people go as far as injecting the hormone, either to slow ageing or to boost their fitness, even though it is not licensed for this kind of use in the UK.
In some countries outside of the European Union, cow growth hormone (bovine somatropin) is used to boost milk production in cows.
Questions for discussion
- What is an ‘acceptable height’ for children who require human growth hormone? Who should decide?
- What are the potential benefits and risks for someone injecting themselves with human growth hormone to slow down ageing?
- What are the arguments for and against the use of cow growth hormone in dairy farming?