Biomedical subjects

I A Hendry

Publications and source records attributed to I A Hendry.

At least 73 records · Page 4Linked to original sources

PubMed1988

Cutaneous stimuli releasing immunoreactive substance P in the dorsal horn of the cat.

In barbiturate-anaesthetized spinal cats, antibody microprobes were used to examine immunoreactive substance P (irSP) release at sites within the spinal cord following cutaneous stimuli. A basal level of irSP release was detected in the region of the substantia gelatinosa of the lumbar spinal cord. No increase in this irSP release was produced by non-noxious thermal or mechanical cutaneous stimulation. Noxious thermal, mechanical or chemical cutaneous stimuli all increased release of irSP in the region of the substantia gelatinosa and in the overlying pia mater. The results support a role for SP in the transmission of information from nociceptors to spinal neurones.

Animals↗

PubMed1988

Mammalian motoneuron development: effect of peripheral deprivation on motoneuron numbers in a marsupial.

In nonmammalian vertebrates, the survival of developing motoneurons is dependent on their contacting appropriate target cells. It is generally accepted that developing mammalian motoneurons have a similar dependency on their target, but as yet there is little experimental evidence to support this contention. This is mainly because of the difficulty of experimenting on eutherian embryos. We have, therefore, been studying neuronal development in the tammar (an Australian marsupial) as its nervous system is immature at birth. Radical or partial removal of hindlimb buds from newborn tammars resulted in an increased motoneuron cell death. The motoneurons which survived in the operated tammars did so by innervating muscle remnants. In the instances where a group of muscles was totally removed, the corresponding motonuclei appeared to be totally lost. This study supports the hypothesis that mammalian motoneurons must contact their appropriate muscle in order to survive through the period of natural neuronal cell death.

Age Factors↗

PubMed1988

Destruction by anti-NGF of autonomic, sudomotor neurones and subsequent hyperinnervation of the foot pad by sensory fibres.

Treatment of newborn rats with antiserum to nerve growth factor (NGF) for the first 6 postnatal days produced a loss of the sympathetic neurones that normally project to the sweat glands of the hind paws of the rat, indicating that cholinergic sympathetic neurones require NGF postnatally for their survival. Following this immunosympathectomy, there was an increase in the proportion of glands containing sensory fibres having substance-P-like immunoreactivity (SP-LI). This sensory sprouting was not as extensive as that after sympathectomy using 6-hydroxydopamine (6-OHDA). During normal development, fibres showing SP-LI are associated with the glands, particularly during the first and second postnatal weeks. Prolongation of the antibody treatment until the third postnatal week reduced the sensory fibre ingrowth from the region of the glands, suggesting that the basis of this growth is the increased availability of NGF following sympathetic denervation. Retrograde cell labelling using the fluorescent dye, fast blue, indicated that the anti-NGF treatment did not significantly decrease the number of sensory neurones projecting to an individual foot pad. These results support the hypothesis that sympathetic and sensory neurones compete for NGF produced by target tissues.

Adrenergic Fibers↗

PubMed1988

Absence of tonic supraspinal control of substance P release in the substantia gelatinosa of the anaesthetized cat.

Antibody microprobes were used to measure immunoreactive substance P (irSP) release in the substantia gelatinosa of the lower lumbar spinal cord of barbiturate-anaesthetized cats. Release of irSP was produced by noxious peripheral stimuli. Such release was not altered by blocking spinal conduction at the first lumbar segment by cooling or transecting the spinal cord. The results suggest that the release of irSP from the central terminals of nociceptors is not subject to tonic supraspinal inhibition.

Animals↗

PubMed1988

The preparation and use of antibody microprobes.

A new method of detecting release of neuropeptides in the central nervous system is described. Glass micropipettes are treated with gamma-aminopropyltriethoxysilane resulting in a fine outer coating of a siloxane polymer containing free amino groups. Glutaraldehyde is then used to covalently couple protein A which in turn binds antibodies to a particular peptide. Following use in the central nervous system, microprobes are incubated in a radiolabelled form of the peptide being studied and release is detected on autoradiographs as localized zones of inhibition of binding of the labelled peptide. The spatial resolution of the method is at least 100 micron. Necessary tests of the validity of the technique are also described.

Animals↗

PubMed1988

Analysis of antibody microprobe autoradiographs by computerized image processing.

A computerized digitizing method to analyze the autoradiographs derived from the antibody microprobe technique is described. The method enables the averaging of groups of microprobes that have been placed in similar locations in the central nervous system during the same physiological stimulation. Control and experimental groups of microprobes can be compared, and a level of significance for the release of a neuropeptide obtained. In addition estimates can be made of the concentration of peptide present in regions of release.

Animals↗

PubMed1987

Noxious heating of the skin releases immunoreactive substance P in the substantia gelatinosa of the cat: a study with antibody microprobes.

Using a new method, the antibody microprobe technique, the release of immunoreactive substance P (SPiR) in the dorsal horn in response to noxious heating of the skin, was studied in barbiturate anaesthetized spinal cats. Release of SPiR was not produced by immersing the ipsilateral hind paw in water at 37 degrees C. With water at 50 and 52 degrees C, however release was consistently detected in the region of the substantia gelatinosa. These results directly show a central release of SPiR with excitation of nociceptors by heat.

Action Potentials↗

PubMed1987

RU38486 blocks the steroid regulation of transmitter choice in cultured rat sympathetic ganglia.

Sympathetic neurones grown in tissue culture change phenotype from adrenergic to cholinergic due to a factor released by non-neuronal cells. Glucocorticosteroids prevent the production of this factor by non-neuronal cells and hence prevent the change in phenotype. Conventional steroid antagonists, however, fail to block this effect. We report here that the steroid antagonist RU38486 is effective in preventing the action of corticosterone on cultured sympathetic ganglia and hence may be a useful in vivo tool to study the steroid regulation of development.

Animals↗

PubMed1987

Morphine dependence in the rat: the appearance in the spinal cord of a dorsal root ganglion cell neurotrophic factor.

An increase in neurotrophic activity for the survival of dissociated sensory neurones has been found in the spinal cord of morphine dependent rats. This activity is not due to morphine itself and is not due to an increase in the nerve growth factor as antibodies to nerve growth factor fail to block the response. A new hypothesis is presented that some of the spinal effects of morphine dependence may be due to an increase in the level of neurotrophic factors as a response to an apparent denervation of the target cells in the spinal cord.

Animals↗

PubMed1987

Use of the fluorescent dye, fast blue, to label sympathetic postganglionic neurones supplying mesenteric arteries and enteric neurones of the rat.

Neuronal pathways in the peripheral nervous system have been traced using the fluorescent dye, Fast blue. Following implantation of a gelatin pellet containing the dye, or direct injection of the dye into the mesentery beside an artery, Fast blue is taken up by both nerve terminals and axons of passage, retrogradely transported by large numbers of sympathetic neurones and retained within the neurones for long periods of time without diffusion. Neurones projecting to both blood vessels of the mesentery and submucosa and to enteric ganglia of the segment supplied by the artery were found labelled in prevertebral and paravertebral ganglia as well as in ganglia lying along the major splanchnic nerves. Attempts to separate the vascular component from those neurones innervating enteric ganglia suggest that the latter are located in the prevertebral, coeliac and superior mesenteric ganglia and to a lesser extent in the splanchnic ganglia, while the vasomotor neurones are located in prevertebral, paravertebral and splanchnic ganglia.

Adrenergic Fibers↗

PubMed1987

Developmental time course of the sympathetic postganglionic innervation of the rat eye.

The time course of the innervation of the rat iris by sympathetic postganglionic axons from the superior cervical ganglion (SCG) has been studied in postnatal rats. A retrogradely transported fluorescent dye, Fast blue (FB) was injected bilaterally into the anterior eye chamber of rats within 3 h of birth or at 7 or 14 days postnatal. Littermates were killed at 24 h intervals, both SCG removed, fixed and sectioned. A substantial number of sympathetic neurones were labelled retrogradely from the eye at birth. The number of labelled cells tripled over the first postnatal week to reach proportions equivalent to those labelled in 3-week-old rats. The degree of sympathetic fibre ingrowth to the iris was examined at 3 postnatal ages, using fluorescence histochemistry. This method showed a small proportion of catecholamine-containing fibres in the iris at birth with a more extensive fibre density over the iris by 7 days after birth. A further increase in fibre density had occurred by the end of the 3rd postnatal week even though the number of cells projecting to the iris at these two ages was similar. This difference in fibre density may arise from ramification of fibres which have reached the iris by 7 days postbirth.

Adrenergic Fibers↗

PubMed1987

Purification of a ciliary neurotrophic factor from bovine heart.

A neurotrophic factor that promotes the survival of cholinergic parasympathetic ciliary neurons has been purified approximately 20,000-fold from bovine cardiac tissue under nondenaturing conditions using heparin-affinity chromatography. Up to 22 micrograms of purified factor having a specific activity of 4 X 10(5) trophic units/mg can be obtained from 250 g of heart muscle. Sodium dodecyl sulfate (SDS)-polyacrylamide gels of the purified material show a broad band that is sometimes resolvable into a closely spaced pair of bands of 22 and 23 kilodaltons. Partially purified factor can be resolved into two peaks of activity (pI 5.6 and 5.0) by high-resolution anion-exchange chromatography and chromatofocusing, although these procedures have not proved useful as purification methods because of the large losses of activity incurred. It is likely that these two peaks represent the two bands seen on SDS-polyacrylamide gels. The bovine cardiac factor(s) differs from similar factors purified from chick optic tissues and pig brain in that it is irreversibly denatured by SDS.

Animals↗

PubMed1986

Laminar localization of the sites of release of immunoreactive substance P in the dorsal horn with antibody-coated microelectrodes.

The localization of the sites of release of immunoreactive substance P (SP) in the spinal cord after peripheral nerve stimulation has been examined in the anaesthetized cat. A new technique using antibodies bound to the outside of glass microelectrodes has allowed the identification of these sites with a spatial precision previously unobtainable. A basal release of SP was detected and this was not increased by electrical stimulation of large myelinated primary afferent fibres. Excitation of unmyelinated primary afferents resulted in the release of high concentrations of SP confined to the region of the substantia gelatinosa and lamina V-VI.

Animals↗

PubMed1986

Long-term retention of Fast Blue in sympathetic neurones after axotomy and regeneration--demonstration of incorrect reconnections.

Using the fluorescent dyes Fast Blue and Diamidino Yellow to trace neuronal connections, the regeneration of the superior cervical ganglionic neurones after axotomy has been examined. Fast Blue has the property of remaining within the neuronal perikaryon for many months after its retrograde axonal transport, even after transection of the axon. Thus, Fast Blue can be used to label neurones as to their original target and Diamidino Yellow subsequently used to demonstrate the specificity of reconnection. The results suggest that apparent return of appropriate function occurs in the presence of a large component of inappropriate reconnections.

Amidines↗

PubMed1986

Binding sites for glycosaminoglycans on developing sympathetic neurones.

Recent studies have suggested that cell to cell communication in the immune system is mediated by cell surface receptors for glycosaminoglycans (GAGs) [Parish et al, 1984]. The intention of this study was to see whether similar recognition molecules for GAGs are present on sympathetic neurones. A mechanical dissociation technique was used to isolate neurones from superior cervical ganglia (SCG) of rats aged between gestational day 19 and postnatal day 21. Receptors for GAGs on sympathetic neurones were detected by the ability of neurones to form rosettes with sheep red blood cells coupled with one of 12 different GAGs. It was found that SCG cells bind to all the GAGs tested. In addition, a range of developmental binding patterns for the various GAGs was found.

Animals↗

PubMed1985

An analysis of peripheral neuronal survival factors present in muscle.

Extracts of bovine heart, rat heart, and rat skeletal muscle were chromatographically separated and the fractions tested for their ability to maintain the survival of dissociated sympathetic, parasympathetic, and sensory neurones. Bovine heart contained at least five, rat heart at least six, and rat skeletal muscle at least four active components differing in their physicochemical properties and their target selectivity. Bovine and rat heart appeared to contain at least two components in common. The differences in active components found in the three tissues are consistent with a complex and perhaps tissue-specific system regulating neuronal survival.

Animals↗

PubMed1985

Subpopulations of sympathetic neurones differ in their sensitivity to nerve growth factor antiserum.

Sympathetic postganglionic nerve fibres supplying mesenteric arteries and intrinsic ileal neurones differ in their characteristics of regeneration. Since the latter population of neurones occurs predominantly in prevertebral ganglia, which have been reported to be spared to some extent after treatment with antiserum to nerve growth factor (anti-NGF), we have investigated whether the two populations were differentially sensitive to anti-NGF. Newborn rats were treated daily for the first postnatal week with either anti-NGF or 154 mM NaCl solution. At 4 and 8 weeks of age, the presence of a functional sympathetic innervation to the mesenteric arteries and the gut was determined and correlated with the fluorescence histochemical demonstration of noradrenergic fibres. At both ages, stimulation of extrinsic sympathetic fibres caused an inhibition of gut motility, while the mesenteric arteries completely lacked a sympathetic innervation. Retrograde labelling of nerve cell bodies in control and antiserum treated rats confirmed that the sympathetic neurones supplying the ileal neurones were located in the prevertebral, superior mesenteric and coeliac ganglia and in the splanchnic ganglia lying along the greater splanchnic nerves. By interference from retrograde labelling in control animals, sympathetic neurones supplying the mesenteric arteries were present in all these ganglia, as well as in the thoracic and lumbar paravertebral sympathetic chains. The results suggest that two functionally distinct populations of sympathetic neurones, which overlap considerably in their distributions, are differentially sensitive to the immunological postnatal removal of NGF.

Animals↗

PubMed1985

Sympathetic neuronal survival factors change after denervation.

The increase in sympathetic neuronal survival factors in the hearts of rats chemically denervated with 6-hydroxydopamine has been examined after biochemical fractionation techniques. Affinity chromatography and gel filtration of extracts of control hearts have demonstrated the existence of two major components, neither of which is nerve growth factor (NGF). The concentrations of both of these components and of NGF are increased significantly after denervation.

Animals↗