Recently, we have shown that the interaction between NGF and sensory neurons in early postnatal periods is restricted to nociceptive afferents (Ritter et al., 1991; Lewin 1992a; Ritter Mendell, 1992). Here show administration of excess neonatal or mature animals can lead a profound behavioral hyperalgesia. Neonatal treatment (postnatal day 0-14) resulted mechanical hyperalgesia persisted until had reached maturity (6 weeks age). This could be explained by an NGF-mediated sensitization A...

Mechanisms underlying the hyperalgesia induced by a single systemic injection of nerve growth factor (NGF) in adult rats were studied vivo. A dose NGF initiated prolonged thermal to radiant heat source within minutes that lasted for days. Animals which had been pretreated with mast cell degranulating compound 48/80 or either one two specific 5-hydroxytryptamine receptor antagonists (ICS 205-930 and methiothepin) also developed an NGF-induced hyperalgesia, but onset was delayed more than 3 h....

Nerve growth factor (NGF) was originally discovered as a neurotrophic essential for the survival of sensory and sympathetic neurons during development. However, in adult NGF has been found to play an important role nociceptor sensitization after tissue injury. The authors outline mechanisms by which activation its cognate receptor, tropomyosin-related kinase A regulates host ion channels, receptors, signaling molecules enhance acute chronic pain. also document that peripherally restricted...

1. Intracellular recordings were made in situ from physiologically identified dorsal root ganglion (DRG) cells untreated rats aged 5-8 wk and treated birth to 5 of age with nerve growth factor (NGF) or antisera against NGF (anti-NGF). 2. As demonstrated cats, the shape somal action potential (AP) DRG normal is correlated peripheral receptor type. Cells that innervate high-threshold mechanoreceptors (HTMRs) thus respond noxious stimulation skin deep tissue periphery have long-duration APs...

1. The individual EPSPs evoked by the action of single Ia fibers from cat triceps surae (MG, LG, SOL) were recorded in homonymous and heteronymous motoneurons innervating these same three muscles. 2. In general, projected to a greater percentage than motoneurons. One class afferent virtually all motoneurons; other had substantially lower projection frequency. Possible difficulties introduced limited resolution averaging technique are discussed. 3. Individual larger on average if a) SOL...

1. Intracellular recordings were made in the somata of dorsal root ganglion cells L7 or S1 DRG cats anesthetized with alpha-chloralose. The properties action potentials (amplitude, duration, peak rate rise), duration afterhyperpolarization (AHP), magnitude inward rectification, and axonal conduction velocity measured. adequate stimulus was determined, extent to which these are correlated investigated. 2. All receptive fields could be classified as mechanoreceptors. Most A-beta-axons (greater...

Three physiologically characterized spindle (group Ia) afferents were labeled by the intracellular injection of HRP and processed for light-level reconstruction. Thirty-five boutons in ventral horn then selected analysis. They serially thin sectioned terms volume, total surface area apposition to postsynaptic neurons (apposed area), mitochondrial vesicle active zone features, relation presynaptic contacts, profile size, position within terminal arbor. Virtually all these characteristics...

Excitatory postsynaptic potentials (EPSPs) were recorded in medial gastrocnemius (MG) motoneurons following intraaxonal electrical stimulation of single spindle afferent fibers anesthetized cats. High-frequency bursts 32 shocks delivered to the axon and EPSPs averaged motoneuron. EPSP amplitude generally changed during burst, some cases increasing other decreasing, depending on connection. Interpretation these changes was complicated by potentiation initial burst that occurred with repeated...

Abstract We compared the effect of viral administration brain‐derived neurotrophic factor (BDNF) or neurotrophin 3 (NT‐3) on locomotor recovery in adult rats with complete thoracic (T10) spinal cord transection injuries, order to determine chronic expression plasticity. At time injury, BDNF, NT‐3 green fluorescent protein (GFP) (control) was delivered lesion via adeno‐associated virus (AAV) constructs. AAV–BDNF significantly more effective than AAV–NT‐3 eliciting locomotion. In fact,...

We investigated acute sensitization by nerve growth factor (NGF) of the response small-diameter (<30 microm) dissociated dorsal root ganglion (DRG) cells to brief repeated puffs capsaicin as a model for thermal hyperalgesia induced NGF. have previously shown that placing NGF in bath after an initial puff can completely overcome tachyphylaxis normally observed second 10 min later, and this is often substantially larger than first. If abolished carrying out experiment Ca2+-free solution, still...

A combination of neuroanatomical and electrophysiological techniques was used to study the effects peripheral axotomy regeneration primary afferents on their central projections in spinal cord. Individual regenerated afferent fibers were impaled with HRP-filled electrodes dorsal columns alpha-chloralose-anesthetized cats activated by current pulses delivered via intracellular electrode. The resulting cord dorsum potentials (CDPs) recorded at four rostrocaudal locations HRP iontophoretically...