Comparative electron histochemistry of thiamine monophosphatase and substance P in the upper dorsal horn

Effect of vinpocetine on retrograde axoplasmic transport

Vinpocetine, a derivate of vincamine, is widely used in the clinical pharmacotherapy of cerebral circulatory diseases. Herewith we report on a novel effect of vinpocetine: inhibition of retrograde axoplasmic transport of nerve growth factor (NGF) in the peripheral nerve. Blockade of retrograde transport of NGF results in transganglionic degenerative atrophy (TDA) in the segmentally related ipsilateral superficial spinal dorsal horn, which is characterized by depletion of the marker enzymes fluoride-resistant acid phosphatase (FRAP) and thiamine monophosphatase (TMP). At the same time, pain-related neuropeptides such as substance P (SP) and calcitonin gene-related peptide (CGRP), are depleted from lamina I-III from the segmentally related, ipsitateral Rolando substance of the spinal cord. On the basis of these experiments it is suggested that vinpocetine may result in a locally restricted decrease of nociception, that might be useful in clinical treatment of intractable pain. Pilot self-experiments support this assumption.

Interaction between substance P-immunoreactive central terminals and gamma-aminobutyric acid-immunoreactive elements in synaptic glomeruli in the lamina II of the chicken spinal cord

We investigated the interaction between gamma-aminobutyric acid (GABA)-immunoreactive (IR) elements and substance P (SP)-IR central terminals in synaptic glomeruli in lamina II of the chicken spinal cord in order to ascertain how pain information is modulated in the spinal dorsal horn. We combined the peroxidase-antiperoxidase (PAP) technique and the protein A-gold (PAG) technique to observe the synaptic relationship between these two components. At the light microscopic level, we observed both GABA-IR and SP-IR elements in the lamina II. GABA-IR elements were also observed in the lamina III. At the electron microscopic level, the following three GABA-IR elements formed synapses with the SP-IR central terminals in synaptic glomeruli: (1) elements which appeared to be axon terminals containing tightly-packed pleomorphic clear vesicles; (2) elements which appeared to be vesicle-containing dendrites with loosely-packed clear and dense-cored vesicles (DCVs); and (3) dendrites without synaptic vesicles. The first type of element was always presynaptic to the SP-IR central terminal. The second type was postsynaptic, presynaptic or in some cases reciprocal to the SP-IR central terminals. The third type was postsynaptic to the SP-IR central terminal. These results suggest that the SP-containing primary afferents activate GABA-containing dendrites and that the SP-containing primary afferents are inhibited presynaptically by GABA-containing neurons through axo-axonic and dendro-axonic synapses.

Coexistence and plasticity of neurotransmitters and neuropeptides in the rat iris

The presence, distribution and origin of substance P (SP), neuropeptide Y (NPY), and CGRP-immunoreactive axons in rat iris were investigated in whole mount preparations, with special respect to the localization of the "classical" adrenergic and cholinergic ground plexuses. SP-IR fibres are distributed parallel to the pupillary margin in the sphincter muscle, and in an irregular plexus in the dilator muscle. The distribution of CGRP-IR fibres was similar to this. Both SP- and CGRP-IR elements originated from the Gasserian ganglion. Following electrocoagulation of the ophthalmic nerve, both SP- and CGRP-IR nerves completely disappeared, while in the caudal nucleus of the trigeminal nerve a substantial decrease of the immunoreactivity was found. NPY-IR fibres have also been demonstrated in the anterior uvea, displaying a pattern similar to that of the adrenergic nerves. In the sympathectomized iris, there was a marked decreased in the density of NPY-IR fibres indicating that NPY most likely coexists with the classical sympathetic neurotransmitter, noradrenalin in the sympathetic nerve supply deriving from the superior cervical ganglion. 1 month after sympathectomy, there was an increase in the density (and possibly also in the number) of both SP- and CGRP-IR fibres in the denervated iris. Subsequent immuno-electron microscopic analysis has demonstrated that both SP- and CGRP-IR fibres are unmyelinated axons, embedded in a common Schwann cell cytoplasm together with a number of axons devoid of immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Substance P-immunoreactive elements in laminae I and II of the chicken spinal cord: a light- and electron-microscopic study

Substance P (SP)-immunoreactive (IR) elements were studied in laminae I and II of the chicken spinal cord in conjunction with an anti-SP monoclonal antibody at light- and electron-microscopic levels by means of the indirect antibody peroxidase-antiperoxidase technique. At the light-microscopic level, SP-IR elements were most intensely observed in the dorsolateral portion of the dorsal horn, laminae I and II. Electron-microscopically, SP-IR boutons contained large spherical dense-cored vesicles (diameter range: 60-125 nm) and spherical clear vesicles. They were subdivided into two groups: large SP-IR boutons, which were the central terminals in synaptic glomeruli, and small SP-IR boutons. In the synaptic glomerulus, two kinds of non-IR presynaptic profiles made axo-axonic synapses with the SP-IR central terminal: one was the presynaptic profile containing pleomorphic clear vesicles and the other was the presynaptic profile containing large dense-cored vesicles. A 'septate junction'-like structure was observed between large SP-IR boutons in synaptic glomeruli. The present results suggest that SP-containing primary afferents are modulated presynaptically by two different neurotransmitter or modulator systems.

Mapping the distribution of thiamine monophosphatase, fluoride-resistant acid phosphatase, and substance P in the spinal cord with a personal computer compatible program

Distribution of the marker enzymes fluoride-resistant acid phosphatase (FRAP) and thiamine monophosphatase (TMPase) as well as that of the marker neuropeptide substance P (SP) has been mapped by means of the semi-automatic computer program MUDH, in various experimental conditions, including degeneration, regeneration, and anti-Nerve Growth Hormone treatment of the sciatic nerve. The program is written in standard Pascal language; it is applicable to Commodore 64 and IBM compatible personal computers. Graphical illustration of values obtained in serial sections is a powerful and highly valuable contribution in the analysis of various biodynamic reactions related to transganglionic regulation of primary sensory neurons.