Back pain, a global health issue affecting people of all ages, often remains a mystery to doctors, making long-term treatment a challenge. However, a groundbreaking study published in Bone Research suggests a potential solution. Hormone therapy, specifically parathyroid hormone (PTH), may be the key to alleviating chronic back pain by curbing abnormal nerve growth in damaged spinal tissue.
Led by Dr. Janet L. Crane, this study offers a fresh perspective on how bone cells influence pain signals in degenerating spines. "Pain-sensing nerves grow where they shouldn't during spinal degeneration, but PTH can reverse this by sending signals to keep these nerves at bay," explains Dr. Crane.
The research team investigated three mouse models mimicking common causes of spinal degeneration: aging, surgical instability, and genetic susceptibility. Over periods ranging from two weeks to two months, mice received daily PTH injections, while control mice received inactive solutions. The results were remarkable.
After treatment, the mice showed improved vertebral endplate structure, becoming less porous and more stable. They also tolerated pressure better, reacted less to heat, and were more active. The team's analysis of nerve fibers revealed a significant reduction in the number of pain-sensing nerves in abnormal locations, as indicated by markers like PGP9.5 and CGRP.
But here's where it gets interesting: PTH stimulates osteoblasts, bone-building cells, to produce a protein called Slit3. This protein acts as a guide, repelling growing nerve fibers and preventing them from invading sensitive areas. Laboratory tests confirmed this, showing that Slit3 directly inhibits nerve growth. Additionally, the researchers identified a regulatory protein, FoxA2, which helps activate Slit3 production in response to PTH, providing further insight into hormone signaling.
While these findings are based on animal models, they may explain why some osteoporosis patients receiving PTH treatments report reduced back pain. Dr. Crane concludes, "Our study suggests that PTH treatment for low back pain during spinal degeneration may reduce abnormal nerve growth, paving the way for clinical trials exploring PTH as a potential treatment for spinal degeneration."
