1. We have compared the effects of partial denervation with those colchicine‐induced block axoplasmic flow, on peripheral fields nerves innervating hind limb salamanders. 2. Acute application colchicine solution (0·03‐0·10 M ) to spinal nerve 16 results in a dose‐dependent increase skin and muscle adjacent (15 17). The time course, magnitude distribution response 0·10 is not distinguishable from that compensatory sprouting 15 17 occurs after section 16. 3. In contrast situation section,...

The expression of neuronal nicotinic ACh receptors (nAChRs) and the subunits that compose these by PC12 cells exposed to NGF has been studied. analysis total RNA reveals nAChR alpha 3, S, beta 2, 4, but not 2 are expressed in our cells. Within 48 hr adding cultures, corresponding 5, 4 is decreased, increases for up 6 d after treatment. To determine influence treatment on subunit protein expression, subunit-specific antisera were prepared. Immunocytochemistry detected antigen (but 4) both...

Programmed cell death is an ongoing process in both the developing and mature nervous system. The tumor suppressor gene, p53, can induce apoptosis a number of different types. Recently, enhanced expression p53 has been observed during acute neurological disease. To determine whether overexpression could influence neuronal survival, we used recombinant adenovirus vector carrying wild type to transduce postmitotic neurons. A control consisting same background but lacZ reporter cassette was...

Determining factors that control the expression of neurotransmitter receptors and mechanisms by which these operate is essential to understand how synapses form during development receptor numbers change in adult. In this study, we have investigated one such factor, influence innervation, on developmental nicotinic ACh (nAChRs) neonatal rat sympathetic neurons, both terms current densities, mRNA levels for transcripts encode receptors. To date, nine genes been cloned neuronal nAChRs subunits...

1. We have investigated the pharmacological properties of functional nicotinic acetylcholine receptors (nAChRs) on neonatal rat sympathetic neurons from superior cervical ganglion (SCG) to learn more about subunit composition these receptors. These express five nAChR transcripts: alpha 3, 5, 7, beta 2, and 4; this finding suggests that SCG may several different, physiologically distinct, subtypes nAChRs. 2. To identify potential subtypes, we characterized currents evoked by different...

Previous investigations showed that the morphological basis of low- threshold rapidly adapting mechanoreceptors in salamander skin is neurite-Merkel cell complex located epidermis. We have now examined whether sensory nerves are required for appearance Merkel cells, and these cells act as specific targets ingrowing axons. Electronmicroscopic examination denervated shows survive normal density epidermis at least six months without nerves. In addition, mechano­sensory function such restored...

1. We have characterized three voltage-gated potassium currents on neonatal rat nodose neurons: a rapidly inactivating current (IAf), slowly (IAs), and noninactivating (IK). 2. Most neurons expressed all currents. However, we found that significant number of had only one the two A-currents. 3. IAf activates (tau = 1.0-1.5 ms at -10 mV) inactivates in 10-30 ms. The activation steady-state inactivation curves were fit with Boltzmann distributions V' -21, k 12 mV -73, -8 mV, respectively. 4....

We have examined the regulation of neuronal nicotinic ACh receptor (nAChR) genes and ACh-evoked currents by neonatal rat sympathetic neurons developing in culture. These contain 5 nAChR transcripts: alpha 3, 5, 7, beta 2, 4. When culture, express 4 these transcripts, 4, at levels similar to those vivo: 3 mRNA increase two- threefold over first week, whereas for remain essentially constant. In contrast, 7 drop 60-75% within 48 hr low. show that during current densities on cultured twofold...

Vertebrate sensory neurons have a pseudo-unipolar morphology; their somata are covered by satellite cells and lack dendrites or synaptic contacts. However, when neonatal rat from the nodose ganglia develop in culture absence of with NGF, they form synapses among themselves. In this study, we investigated whether express under same conditions. We show Lucifer yellow injection that remain typically unipolar cocultured ganglionic cells. these cultured without cells, virtually all acquire...

External rectal prolapse is poorly understood, with controversy surrounding the ideal surgical approach. Anecdotal mentions of high and low take-off in literature hint at different pathological phenotypes prolapse. However there has been no effort to define characterise these terms, or discuss how might relate underlying pathophysiology We aimed determine if defaecation proctography (DPG) could reliably The study was a retrospective analysis prospectively collected data. A total 88 patients...

1. We have investigated the developmental expression of three voltage-gated K currents on neonatal rat superior cervical ganglion (SCG) neurons in vivo and culture: a rapidly inactivating current (IAf), slowly (IAs), noninactivating (IK). 2. On postnatal day 1 (P1), mean peak IAs is 67 +/- 4 (SE) pA/pF, IAf 27 3 IK 14 pA/pF. Over next wk, there switch these currents: drops by 40%, whereas increases greater than 100%; no change IK. P14 neurons, 38 2 64 5 12 3. The SCG over first wk unaffected...

Sensory neurones from new‐born rat nodose ganglia were grown in tissue culture, either with or without the ganglionic satellite cells, order to investigate influences of cells on sensory neurone development. To learn more about post‐natal development rats neuronal counts ganglion made at three different developmental stages. There no significant differences number rats, 3 weeks age, and adult rats. Up 60% formed synapses each other when they developed culture cells. Pharmacological...

Cultured sensory neurons from nodose ganglia were investigated with whole-cell patch-clamp techniques and single-channel recordings to characterize the A current. Membrane depolarization -40 mV holding potential activated delayed rectifier current (IK) at potentials positive -30 mV; this had a sigmoidal time course showed little or no inactivation. In most neurons, was completely inactivated required hyperpolarization remove inactivation; isolated by subtracting IK evoked depolarizations...

Single channels that underlie the fast transient potassium current (IA) were recorded, using patch‐clamp techniques, from cultured sensory neurones. The open channel conductance was approximately 22 pS, and constant over most of physiological voltage range; single‐channel decreased at more depolarized levels. Summing currents resulted in an average whose kinetics similar to macroscopic IA. inactivation these currents, potentials we studied, fitted with a single exponential time 30 ms. For...

1. Neurones of the nodose ganglion vagus nerve were dissociated from new‐born rats and grown in virtual absence non‐neuronal cells presence growth factor. 2. The resting potentials neurones ranged ‐40 to ‐80 mV. Action short duration, with no inflexion on falling phase; others longer duration a hump phase. 3. inward current action potential was carried either predominantly by Na+ or Ca2+. 4. Tetrodotoxin (1 microM) blocked channels some but other partially completely resistant tetrodotoxin...

We have shown that when one of the spinal nerves supplying salamander hind limb is cut or treated with colchicine, fields remaining enlarge in area; whereas nerve section produces Wallerian degeneration, colchicine-treated conducted action potentials normally and their peripheral remained unchanged area (Aguilar, Bisby, Cooper & Diamond, 1973). Since colchicine-treatment reduced neuronal transport, nerve-section eliminated it, we proposed sprouting regulated by factors conveyed to endings...