Pain in osteoarthritis (OA) results from erosion of joint cartilage, resulting in bone contacting bone without an intervening cushion. The periosteum, including its nociceptive innervation, ends at the border of the cartilage meaning that there is no extrinsic neuronal pathway between the opposing denuded bone surfaces to carry a bone-on-bone pain signal to the brain. The pain signaling pathway must therefore originate in nociceptive sensory endings within the subchondral bone itself. Selective ablation of this intrinsic nerve pathway, using any of a variety of approaches, is expected to permanently eliminate OA pain.

Women are at higher risk of cognitive impairment and Alzheimer’s disease (AD) after menopause when the estrous cycle becomes irregular and begins to taper off. Numerous studies have shown that estrogen deficiency, especially estradiol (E2), has been shown to play a key role in this phenomenon. Recently, a novel polymeric drug, hyaluronic acid-17β-Estradiol conjugate (HA-E2), has been developed which has the ability to cross the blood-brain barrier (BBB), facilitate a longer E2 release profile and lower risk of estrogen supplement related side effects. In this study, we used an ovariohysterectomy (OHE) rat model of postmenopausal cognitive deficits and explore whether HA-E2 treatment can improve the cholinergic septo-hippocampal innervation system, synaptic transmission in the hippocampal pyramidal neuron and cognitive impairment. Our results show that OHE rats after HA-E2 administration have increased expression of choline acetyltransferase (ChAT) in the medial septal nucleus (MS nucleus) and the hippocampus, increased spine density in hippocampal pyramidal neurons, and improved spatial learning and memory. Therefore, HA-E2 has great potential as a new novel class of drugs for estrogen-deficiency-induced cognitive impairment and AD.

Nociceptive innervation of the thoracolumbar fascia (TLF) has been investigated over decades, however these studies have not been compiled or collectively appraised. The purpose of this scoping review was to assess current knowledge regarding nociceptive innervation of the TLF to better inform future mechanistic and clinical TLF research targeting low back pain (LBP) treatment. PubMed, ScienceDirect, Cochrane and Embase databases were searched in January 2021 using relevant descriptors encompassing fascia and pain. Eligible studies were: (a) published in English; (b) preclinical and clinical (in vivo and ex vivo) studies; (c) original data; (d) included quantification of at least one TLF nociceptive component. Two-phase screening procedures were conducted by a pair of independent reviewers, data were extracted and summarized from eligible studies. The search resulted in 257 articles of which 10 met inclusion criteria. Studies showed histological evidence of nociceptive nerve fibers terminating in low back fascia, suggesting a TLF contribution to LBP. Noxious chemical injection or electrical stimulation into fascia resulted in longer pain duration and higher pain intensities than injections into subcutaneous tissue or muscle. Pre-clinical and clinical research provides histological and functional evidence of nociceptive innervation of TLF. Greater knowledge of fascial neurological components could impact LBP treatment.