Building blocks of pain: the regulation of key molecules in spinal sensory neurones during development and following peripheral axotomy

Abstract

The pathways, synapses and molecules involved in pain processing in the newborn are not only required to trigger repair and recuperation but are also involved in the process of forming a mature nervous system. Sensory neurons in the dorsal root ganglion and dorsal horn express a phenomenal array of molecules which contribute to their structural and functional characteristics and many of these are developmentally regulated both pre- and postnatally. In order to understand nociceptive signalling and pain in the neonate we need a clear picture of that regulation. This review concentrates on the changing expression of selected key molecules, receptors and channels in the embryo, neonate and adult, which both characterise the sensory neuron and contribute to its response to painful stimuli in normal and pathological conditions.

Expression of Neurotrophic Factors in Neonatal Rats After Peripheral Inflammation

“…Later in the postnatal stage, neurotrophins regulate the primary afferent innervation density of both central and peripheral targets and influence the physiologic phenotype of peripheral sensory receptors. 1,9,47 In adults, neurotrophins play an important role as mediators of inflammatory hyperalgesia in both peripheral and central sensory nervous systems. 23,31,48 As a member of the neurotrophin family, NGF has been demonstrated to regulate the expression of other neurotransmitters and their receptors.…”

Characterization of μ Opioid Receptor Binding and G Protein Coupling in Rat Hypothalamus, Spinal Cord, and Primary Afferent Neurons during Inflammatory Pain

“…For human neuroblastoma cells it was shown recently that an increase in MOP receptor mRNA might be related to mediators of inflammation (e.g., interleukin-4, tumor necrosis factor) (Kraus et al, 2001). In addition, nerve growth factor is also thought to be critical for altered gene transcription and protein synthesis in DRG neurons (Lindsay and Harmar, 1989;Alvares and Fitzgerald, 1999).…”

Activation of Src-Family Kinases in Spinal Microglia Contributes to Mechanical Hypersensitivity after Nerve Injury

“…After nerve injury, plastic changes occur in the expression of ion channels, receptors, neuropeptides, and signal transduction-related molecules in the peripheral nervous system and CNS (Scholz and Woolf, 2002;Ji and Strichartz, 2004). In previous studies, much attention has been focused on the primary sensory neurons and their influence on the activity of spinal dorsal horn neurons (Hokfelt et al, 1994;Alvares and Fitzgerald, 1999). However, there is increasing evidence suggesting that glial cells in the spinal cord may also play a role in the pathogenesis of neuropathic pain (Tsuda et al, 2005;Marchand et al, 2005).…”