Estrogen plays an important role in determining how sensitive a person is to pain, and the estrogen receptor known as ER-beta is particularly significant in this context. These are the conclusions of a study from the Swedish medical university Karolinska Institutet.

"This may mark the beginning of the production of a new class of analgesic drugs", says Professor Jan-Åke Gustafsson, Department of Biosciences and Nutrition.

Earlier studies have shown that estrogen affects how we experience pain, but the mechanisms behind this have been unclear. Estrogen can bind to two different receptors, known as ER-alpha and ER-beta, and the new study describes results obtained concerning the expression of these two receptors in the spinal cord.



The results show that ER-beta plays an important role in the development of the part of the spinal cord that contains nerve fibres that carry information to the brain. These nerves are important in several functions, including determining how sensitive a person is to pain, and response to sensation in general.

ER-beta is the dominant estrogen receptor during the development of the embryo. The researchers also showed that neuronal development occurs later in mice that lack ER-beta, and that ER-beta is important in the spinal cord of the adult animal for the survival of nerve cells and for the transmission of pain and sensation.

"These results are particularly interesting in the light of preliminary results from pre-clinical studies that suggest that substances that stimulate ER-beta can give pain relief", says Jan-Åke Gustafsson.