Question

Soon after the discovery of nerve growth factor, researchers injected newborn mice with antibodies against NGF which bind NGF and block its cell receptors. They observed massive nerve cell death compared to appropriate control injections with no antibodies. What is the reason for the observed nerve cell death?

1) The antibodies caused an immune response that led to nerve cell death.
2) The antibodies prevented NGF from binding to its cell receptors, causing nerve cell death.
3) The antibodies directly caused the death of nerve cells.
4) The antibodies had no effect on nerve cell death.

Answer 1

Nerve cell death was most likely due to antibodies blocking NGF from binding to its cell receptors, which are essential for neuronal survival and maintenance, resulting in programmed cell death or apoptosis.

Step-by-step explanation:

The observed nerve cell death in the experiment is most likely due to the fact that the antibodies prevented nerve growth factor (NGF) from binding to its cell receptors. NGF is crucial for the survival and maintenance of certain types of neurons. When antibodies bind to NGF, they inhibit its action by blocking its interaction with the NGF receptors on the surface of nerve cells.

As a result, the nerve cells, unable to receive the necessary survival signals from NGF, undergo programmed cell death, known as apoptosis. This process of cell death can be compared to other instances where antibodies disrupt cell function, such as when antibodies produced by the body bind to acetylcholine receptors in myasthenia gravis, which prevents the neurotransmitter acetylcholine from stimulating muscle contraction, leading to muscle weakness.