The transneuronal induction of sprouting and synapse formation in intact mouse muscles.

Abstract

SUMMARY1. The pattern of innervation to intact peroneal and extensor digitorum longus muscles of normal and experimental young adult mice was studied by light microscopy after staining neuromuscular junctions by a combined silver-cholinesterase stain.2. Spontaneous sprouting and synapse formation occur in intact muscles of normal mice. In about 7 % of the junctions, sprouts contribute to the innervation of muscle fibres already innervated by their parent axons. 3. Axotomy of the sciatic nerve in one hind limb is followed by an average 3-fold increase over normal in the incidence ofsprouting and synapse formation in the intact muscles of the opposite hind limb.4. The time to onset of sprouting and synapse formation becomes shorter as the site of the contralateral axotomy is placed closer to the spinal cord. A significant increase over normal in the incidence of sprouting is first observed 5 days after a proximal sciatic nerve cut and only 12 days after a distal sciatic nerve cut.5. The timing of sprouting is independent of the difference in the number of axons that are involved in the contralateral axotomies at different sites.6. These findings suggest that, in the intact muscles of normal mice, sprouting and synapse formation is an ongoing process which can be enhanced by contralateral axotomy. As in frogs (Rotshenker, 1979(Rotshenker, , 1982) the underlying mechanism may be the transneuronal induction of sprouting and synapse formation.

Segmental and propriospinal projection systems of frog lumbar interneurons

“…To the extent that this possibility may be true, the conclusions from the present studies must be qualified. Chronic axonal transections of the type used in the present study can have effects both on those neurons that have their axons cut and on those transynaptic to the affected neuron (Anderson and Flumerfelt 1986;Carlson et al 1976;Farel 1980;Rosenthal and Cruce 1984;Rotshenker and Tal 1985). Axotomy can induce both morphological (Cruce 1974;Rosenthal andCruce 1984) andphysiological (Carlson et al 1976;Farel 1980) changes in neurons.…”

Neuropeptide gene expression and capsaicin‐sensitive primary afferents: maintenance and spread of adjuvant arthritis in the rat.

“…The effect of nerve injury on contralateral motoneurons in rodents was initially reported by Rotschenker & Tal (1985), who suggested that motoneurons contralateral to an axotomized motor nerve sprouted in response to a transneuronal signal from the injured neurons mediated through the spinal cord. More recently, in models of unilateral nerve injury and neuropathic pain, bilateral changes have been reported in nociceptive thresholds (Kim & Chung, 1992), protein kinase C levels and spinal cord metabolic activity, as assessed by ['4C] 2-deoxyglucose uptake (Mao, Mayer, Hayes & Price, 1993), and opioid receptor binding (Stevens, Kajander, Bennett & Seybold, 1991).…”

Climbing Fibre Plasticity in the Cerebellum of the Adult Rat

“…In previous studies, these phenomena have been demonstrated either by changes in the pattern of the lamination of afferent systems at the light microscopic level, or by alterations in the distribution of synaptic contacts detected in the electron microscope (for reviews see Cotman er al., 1981;Cotman and Anderson, 1988;Goldberger and Murray, 1988). By contrast, the complete description of the emergence, the course, and the pattern of terminal branching of newly formed axons has never been provided in the adult brain, although such a picture is available for plastic phenomena in the peripheral nervous system (Edds, 1953;Slack et al, 1979;Rotshenker and Tal, 1985;Rotshenker, 1988) and the developing visual system (Robson et al, 1978). The olivocerebellar system provides a favourable model of investigation because of its stereotypic organization, which resembles that of the motor unit.…”