Our new finding shows that it also makes itch worse by activating GRPR
neurons through 5HT1A receptors.
We analyzed the immunohistochemical expression of GRPR in 238 lung cancer archival cases selected from the department of pathology files of Hospital das Clinicas from the University of Rio Grande do Sul (Porto Alegre, Brazil), based on the availability of formalin-fixed, paraffin-embedded tissue blocks from 2004 to 2008.
Immunohistochemical stain for GRPR (rabbit polyclonal antibody, OPA1-15619, 1:200 dilution; Affinity Bioreagents, Golden, Colorado) was performed on formalin-fixed, paraffin-embedded tissue blocks from all cases sectioned at 4-[micro]m thickness.
Five entire high-power fields (X40) containing clusters of malignant cells were identified per slide and scored for intensity and percentage of GRPR staining expression.
So this time, Chen's team injected the spinal cords of mice with a neurotoxin that seeks out the GRPR
receptor, sort of a docking site.
Among people who had smoked less than the equivalent of a pack of cigarettes a day over 25 years, 75 percent of the women and 20 percent of the men had active GRPR copies, she says.
The incidence of lung cancer was 12 times higher for women with an active GRPR gene than for women with inactive genes.
GRPR makes a receptor found in a very small population of nerve cells in the spinal cord.
We hypothesized that GRPR may be responsible for the itching but not involved in the pain response," Chen said.
Therefore, the researchers went back to the mice bred with and without GRPR and compared both scratching behaviours and pain-killing effects following spinal injections of morphine.