Characterization of afferent and efferent galanin-containing nerve fibres in the porcine ovary

Double-labelling immunofluorescence combined with retrograde tracing revealed three subpopulations of galanin-immunoreactive nerve fibres innervating the porcine ovary. The first group originated in ipsilateral dorsal root ganglia Th11-L5 and exhibited colocalization with substance P-, but not with tyrosine-hydroxylase- or dopamine-beta-hydroxylase-immunoreactivity. These fibres supplied primordial follicles and large arteries of the ovarian hilus. The second group, arising from the sympathetic inferior mesenteric ganglion, was galanin-immunoreactive, but non-reactive to substance P-, dopamine-beta-hydroxylase- or tyrosine-hydroxylase-antisera. Fibres of this type were sparsely distributed in the ovarian cortex. They were observed in connection with small cortical arterioles or in the ovarian cortical stroma. The third group of galanin-containing nerve terminals originated from postganglionic neurons located in sympathetic chain ganglia Th15-L3 and S1. Most of them contained tyrosine-hydroxylase- and dopamine-beta-hydroxylase-immunoreactivity. This subset of galanin-positive nerve fibres was the least frequent and was almost exclusively associated with cortical arterioles. The findings are indicative of an involvement of galanin in autonomic and sensory neuronal functions in the ovaries, possibly control of follicle maturation and blood flow.     

Group conduction velocities and nerve fibre diameters of alpha and gamma-motoneurons from lower sacral nerve roots of the dog and humans.

Single action potentials and their conduction times were recorded extracellularly from dog and human lower sacral nerve roots. Conduction velocity frequency distribution histograms were constructed and peaks of single extrafusal and intrafusal motoneuron distributions were identified. The electrophysiologically measured roots were removed and morphometrically analysed. Nerve fibre diameter frequency distribution histograms were constructed with respect to 3 myelin sheath thickness ranges, and peaks of single motoneuron group distributions were identified. The identified motoneuron classes, characterized by their group peak values of conduction velocity at about 36 degrees C and fibre diameter were: dog: intrafusal: gamma 22(23ms-1/4.8 microns),gamma 21(33/5.7), gamma 1 (43/6.7),gamma beta?(54/10.1) extrafusal: alpha 3(61ms-1/11.7 microns),alpha 2(72/13.6), alpha 11 (81/15.2), alpha 12(86/16.8),alpha 13(95/19) human: intrafusal: gamma 21(15ms-1/5.8 microns), gamma 1(20/6.8), gamma beta?(27/7.2) extrafusal: alpha 3(37ms-1/8.3 microns),alpha 2(50/10.2), alpha 1(60/13.1) The 60 (alpha 3) to 30% (alpha 1-motoneurons) higher conduction velocities in dogs as compared to humans seem to originate in the 40 (alpha 3) to 30% (alpha 1-motoneurons) larger nerve fibre diameters. However, the myelin sheath seemed to be 0.1 to 0.2 microns thinner in dogs than in humans. The pair-values "conduction velocity-fibre diameter" of the alpha and gamma-motoneuron groups were lying on different correlation curves in the velocity-diameter plane indicating structural and/or geometrical differences between alpha and gamma-motoneurons.     

Renorenal reflexes: interaction between efferent and afferent renal nerve activity.

In rats, stimulation of renal mechanoreceptors by increasing ureteral pressure results in a contralateral inhibitory renorenal reflex response consisting of increases in ipsilateral afferent renal nerve activity, decreases in contralateral efferent renal nerve activity, and increases in contralateral urine flow rate and urinary sodium excretion. Mean arterial pressure is unchanged. To study possible functional central interaction among the afferent renal nerves and the aortic and carotid sinus nerves, the responses to renal mechanoreceptor stimulation were compared in sinoaortic denervated rats and sham-denervated rats before and after vagotomy. In contrast to sham-denervated rats, there was an increase in mean arterial pressure in response to renal mechanoreceptor stimulation in sinoaortic-denervated rats. However, there were no differences in the renorenal reflex responses among the groups. Thus, our data failed to support a functional central interaction among the renal, carotid sinus, and aortic afferent nerves in the renorenal reflex response to renal mechanoreceptor stimulation. Studies to examine peripheral interaction between efferent and afferent renal nerves showed that marked reduction in efferent renal nerve activity produced by spinal cord section at T6, ganglionic blockade, volume expansion, or stretch of the junction of superior vena cava and right atrium abolished the responses in afferent renal nerve activity and contralateral renal function to renal mechanoreceptor stimulation. Conversely, increases in efferent renal nerve activity caused by thermal cutaneous stimulation increased basal afferent renal nerve activity and its responses to renal mechanoreceptor stimulation. These data suggest a facilitatory role of efferent renal nerves on renal sensory receptors.     

Immunohistochemical correlation of human adrenal nerve fibres and thoracic dorsal root neurons with special reference to substance P

Applying a double-labelling immunofluorescence technique, six types of substance P-containing nerve fibres were distinguished in the human adrenal gland according to the immunohistochemical colocalization of (I) calcitonin gene-related peptide (CGRP), (II) cholecystokinin, (III) nitric oxide synthase, (IV) dynorphin, (V) somatostatin, and (VI) vasoactive intestinal polypeptide. Fibre populations I to IV in their mediator content resembled the respective subpopulations of primary sensory neurons in human thoracic dorsal root ganglia, while populations V and VI revealed no correspondence with dorsal root neurochemical coding. Nerve fibres with the combination substance P/nitric oxide synthase occurred only in the adrenal cortex, whereas all other fibre types were present in both cortex and medulla. As revealed by immuno-electron microscopy, substance P-immunolabelled axon varicosities (a) exhibited synaptic contacts with medullary chromaffin cells or with neuronal dendrites, (b) were directly apposed to cortical steroid cells and (c) were separated from fenestrated capillaries only by the interstitial space. These findings provide immunochemical support for an assumed sensory innervation of the human adrenal gland, and additionally suggest participation of substance P in efferent autonomic pathways. Furthermore, the results are indicative for a differentiated involvement of substance P in the direct and indirect regulation of neuroneuronal and neuroendocrine interactions.     

Peptide immunoreactivity of unmyelinated primary afferent axons in rat lumbar dorsal roots

The present study demonstrates calcitonin gene-related peptide (CGRP), somatostatin (SOM), bombesin (BOM), and substance P (SP) at the electron microscopic level in lumbar dorsal root axons of normal rats. The highest percentages of labeled axons were for CGRP (14%) and then, in descending order, for SP (8.6%), SOM (6.8%), and BOM (3.1%). The labeled axons were exclusively unmyelinated for SP, SOM, and BOM, and predominantly unmyelinated for CGRP. These data are consistent with the data for labeled sensory cell bodies for these same compounds. We emphasize that these peptides were immunocytochemically visualized in the dorsal roots without experimental manipulation, such as colchicine or dorsal root ligation. Quantitative sampling of this type can be used to assay changes in response to physiological stimuli in numbers of sensory axons that contain identifiable concentrations of these peptides.     

Routing of transported materials in the dorsal root and nerve fiber branches of the dorsal root ganglion

After injection of the L7 dorsal root ganglion with ³H-leucine, fast axoplasmic transport carries some 3–5 × more labeled materials down the sensory fibers branches entering the sciatic nerve as compared to the dorsal root fiber branches of the neurons. Freeze-substitution preparations taken from the two sides of the lumbar seventh dorsal root ganglia of cats and monkeys showed little difference in the histograms of nerve fiber diameters of the sensory nerve fiber branch of these neurons as compared to the dorsal root fiber branches. A similar density of microtubules and of neurofilaments in the dorsal root and sensory nerve fiber branches over a wide range of fiber diameters was found in electron micrograph preparations. In the absence of an anatomical difference in the fibers to account for the asymmetrical outflow, a functional explanation based on the transport filament model was advanced.     

Mucopolysaccharides in the dog spinal cord and dorsal root ganglia. A histochemical study.

A histochemical study of mucopolysaccharides in the dog spinal cord and dorsal root ganglia is reported in this paper. The histochemical techniques used were the following: PAS, colloidal iron, toluidine blue (pH 5.4 and 3.5), thionine (pH 5.4 and 3.5) and alcian blue 8GX (pH 1 and 2.5). Some histological stains were used also. Two types of neurons could be observed in spinal cord sections stained with colloidal iron techniques. In some neuron a border line of mucosubstances could be seen. In the dorsal root ganglia, different patterns of Nissl bodies distribution in neurons were described. This different distribution of Nissl bodies is associated with different metachromatic colorations of neurons. By using the colloidal iron method, two types of neurons were also revealed in the dorsal root ganglia: some neurons are of a yellow, small-sized and star-shaped type and others are of a light green, larger and round-shaped type. Mucosubstances in the endoneurium and perineurium of nerve fibers, in the Ranvier nodules and in the Schmidt-Lantermann incisures were observed. The possibility that the functional rhythm in some cases might be responsible for the difference in coloration between the dorsal root ganglia neurons is suggested.     

In vivo measurement of conduction velocities in afferent and efferent nerve fibre groups in mice

Electrophysiological investigations in mice, particularly with altered myelination, require reference data of the nerve conduction velocity (CV). CVs of different fibre groups were determined in the hindlimb of anaesthetized adult mice. Differentiation between afferent and efferent fibres was performed by recording at dorsal roots and stimulating at ventral roots, respectively. Correspondingly, recording or stimulation was performed at peripheral hindlimb nerves. Stimulation was performed with graded strength to differentiate between fibre groups. CVs of the same fibre groups were different in different nerves of the hindlimb. CVs for motor fibres were for the tibial nerve (Tib) 38.5±4.0 m/s (Agamma: 16.7±3.0 m/s), the sural nerve (Sur) 39.3±3.1 m/s (12.0±0.8 m/s) and the common peroneal nerve (Per) 46.7±4.7 m/s (22.2±4.4 m/s). CVs for group I afferents were 47.4±3.1 m/s (Tib), 43.8±3.8 m/s (Sur), 55.2±6.1 m/s (Per) and 42.9±4.3 m/s for the posterior biceps (PB). CVs of higher threshold afferents, presumably muscle and cutaneous, cover a broad range and do not really exhibit nerve specific differences. Ranges are for group II 22-38 m/s, for group III 9-19 m/s, and for group IV 0.8-0.9 m/s. Incontrovertible evidence was found for the presence of motor fibres in the sural nerve. The results are useful as references for further electrophysiological investigations particularly in genetically modified mice with myelination changes.     

Histochemically demonstrable catecholamines and cholinesterases in nerve fibres of rat dorsal skin

Summary Histochemically demonstrable cholinesterases of rat skin and cutaneous nerves hydrolyze acetylthiocholine iodide and butyrylthiocholine iodide. Cholinesterase activity of the skin was located in the epidermis, in the hair follicles at the level of the sebaceous glands, in adjacent parts of the sebaceous glands, in erector pili muscles and their nerves, in cutaneous and subcutaneous nerves and nerve trunks, including some nerves accompanying cutaneous blood vessels, and in the membranes of fat cells. No encapsulated nerve endings were found. In the nerves of erector pili muscles there was some neurilemmal non-specific cholinesterase activity, demonstrated in the presence of 10^–5 M BW 284C 51, and specific acetylcholinesterase activity resistant to 10^–5 M iso-OMPA. The cholinesterase activity in other cutaneous nerves was inhibited by 10^–5 M iso-OMPA but was resistant to 10^–5 M BW284 C 51, thus representing mainly non-specifc cholinesterase (nsChE) activity.The adrenergic nerves of the dorsal skin, as revealed by glyoxylic acid-induced fluorescence (GIF), were located in association with erector pili muscles and surrounded arteries and arterioles. Small fluorescent nerves were situated in subcutaneous nsChE-positive nerve trunks.Using GIF and cholinesterase techniques performed either simultaneously or consecutively, it was found that the nsChE-positive, probably sensory, nerves accompanying blood vessels were fewer in number than the fluorescent adrenergic nerves and ran a course independent of them. No cholinesterase reaction was seen in the fluorescent adrenergic nerves when short incubation times were used. When the incubation time was prolonged overnight, the nsChE reaction closely followed the course of fluorescent adrenergic nerves.     

Structural basis of sympathetic-sensory coupling in rat and human dorsal root ganglia following peripheral nerve injury

Tyrosine hydroxylase immunocytochemistry was used to reveal the sympathetic postganglionic axons that sprout to form basket-like skeins around the somata of some primary sensory neurons in dorsal root ganglia (DRGs) following sciatic nerve injury. Ultrastructural observations in rats revealed that these sprouts grow on the surface of glial lamellae that form on the neurons. Sciatic nerve injury triggers glial cell proliferation in the DRG, and the formation of multilamellar pericellular onion bulb sheaths, primarily around large diameter DRG neurons. We infer that these glia participate in the sprouting process by releasing neurotrophins and expressing growth supportive cell surface molecules. Many DRG cell somata, and their axons in intact nerves and nerve end neuromas, express α2A adrenoreceptors intracytoplasmically and on their membrane surface. However, sympathetic axons never make direct contacts with the soma membrane. The functional coupling known to occur between sympathetic efferents and DRG neurons must therefore be mediated by the diffusion of neurotransmitter molecules in the extracellular space. Sympathetic basket-skeins were observed in DRGs removed from human neuropathic pain patients, but the possibility of a functional relation between these structures and sensory symptoms remains speculative.     

Control of defecation in patients with spinal injuries by stimulation of sacral anterior nerve roots.

OBJECTIVE--To observe the effects of stimulation of the sacral anterior roots on anorectal and low colonic pressures and to programme implanted stimulators to produce defecation. DESIGN--Prospective study of 12 consecutive patients. SETTING--Spinal injuries unit and university gastrointestinal physiology department. PATIENTS--12 Patients with complete supraconal spinal cord lesions. Their injuries had been sustained at least two years before the study. INTERVENTIONS--A Brindley-Finetech intradural sacral anterior root stimulator was implanted in all patients. Three months postoperatively the stimulator settings were adjusted after measurement of simultaneous anorectal and low colonic pressures. MAIN OUTCOME MEASURES--Full defecation. RESULTS--Six patients achieved complete rectal evacuation of faeces using the implant and subsequently did not require manual help for defecation. For all but one of the patients the total time taken to complete defecation was reduced, and all were free from constipation, the most prevalent gastrointestinal symptom in patients with spinal injuries. CONCLUSIONS--Sacral anterior root stimulators can be programmed to achieve complete unassisted defecation and can considerably improve the quality of life of patients with spinal injuries.     

Glutamate-immunoreactivity in the trigeminal and dorsal root ganglia, and intraspinal neurons and fibres in the dorsal horn of the rat

Summary Putative aspartergic and glutamatergic sensory neurons in the rat were identified by autoradiography and immunocytochemistry respectively. Approximately 3% of large L₄ dorsal root ganglion neurons (diameter 18–52 m) accumulated radiolabelled aspartate, whereas all satellite glia had high affinity for the amino acid. Glutamate-immunofluorescent (Glu-FITC) dorsal root ganglia neurons comprised 38.3% at S₁, 35.6% at L₂ 33.9% at C₅ and 28.8% at T₆. Numbers of immunoreactive neurons were higher with the more sensitive peroxidase-anti-peroxidase (Glu-PAP) method; and the cell counts totalled 42% (S₁), 41.2% (L₄), 35% (C₅) and 34.6% (T₆). The trigeminal ganglion (TG) contained 24% Glu-FITC and 32.3% Glu-PAP positive cells. The majority of glutamate-immunoreactive sensory neurons were small, ranging from 10–35 m with median diameters of 17.5m (C₅), 21m (S₁), 24.2m (TG) and 28.5 m (L₂). It is evident therefore, that a subgroup of class B cells are glutamatergic. Glutamate immunoreactivity in the spinal cord was similar in all segments and was localized in the superficial lamina and substantia gelatinosa of the dorsal horn. Stained interneurons were located among the immunoreactive fibres. The dorsolateral funiculus contained dense plexus of immunoreactive fibres which increased in prominence after intraperitoneal injection of L-glutamate, but penetration of exogenous glutamate into the grey matter was limited. Instead, the meninges and basal layers of the spinal blood vessels were intensely immunoreactive. The studies describe the subtypes of acidic amino acidergic neurons and relates the immunohistochemistry to a functional subclass.     

Electrotonic and chemical EPSPs evoked in lamprey motoneurons by descending tract and dorsal root afferent stimulation

Postsynaptic responses evoked by stimulation of the descending tract and dorsal roots were investigated by means of intracellular microelectrodes in experiments on preparation of the isolated lamprey spinal cord. Besides giant reticulospinal (Mullerian) axons, a broad spectrum of descending fibers and dorsal-root afferents were shown to form synaptic inputs with both chemical and electrical mechanisms of transmission with motoneurons, as revealed by the sensitivity of the corresponding PSPs to absence of calcium ions and excess of magnesium ions in the external medium. During combined stimulation electrotonic PSPs may have a rapid temporal course characteristic of elementary responses, but they may also lead to smooth and slow depolarization of the postsynaptic membrane, evidence that they may perform not only a mediator but also an integrative function.I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 9, No. 5, pp. 512–517, September–October, 1977.