Number Of Horseradish Peroxidase Research Articles

Enhancement of rat hypoglossal nerve regeneration by chitin sheet plus gangliosides

The effects of chitin sheet interposition with and without brain gangliosides on the regeneration of hypoglossal nerve fibres was studied in the rat following resection of a 5mm length of the nerve. At 10 weeks after operation, the number of horseradish peroxidase (HRP)-labelled motor neurones, indicative of the axonal repair process, on the side treated with chitin and gangliosides was higher than on the control side (where 5mm of the nerve was simply resected). The ratios of HRP-positive neurones in the right hypoglossal nucleus (treated side)/left hypoglossal nucleus (intact side) was 0 in the 5mm-resected group, 53% in the chitin-grafted group, 88% in the ganglioside (0.2 microg)-injected group, 90% in the ganglioside (2 microg)-injected group, 91% in the chitin with ganglioside (0.2mg)-injected group, 91% in the chitin with ganglioside (2 microg)-injected group and 85% in the autograft group, respectively. There were significant differences between the 5 mm-resected group and chitin-grafted group, ganglioside-injected group, chitin with ganglioside group and autograft group, and between the chitin-grafted group and ganglioside-injected, chitin with ganglioside and autograft groups (P< 0.005, respectively). Our results indicated that the use of chitin and gangliosides stimulated the regeneration of severed motor nerve fibres. These findings suggest that chitin and gangliosides might be therapeutically useful for treatment of neuronal degeneration.

Low power laser irradiation alters the rate of regeneration of the rat facial nerve.

Low power laser irradiation has been reported to cause biological effects due to the photochemical and/or photophysical action of the radiation. This study determined quantitatively if transcutaneous low power laser irradiation can affect the regeneration of the rat facial nerve. The facial nerve was crushed unilaterally in anesthetized rats and transcutaneously irradiated daily with a laser beam directed at the area of the crush injury. Laser treatment began on the day of the crush injury and was continued daily for 7, 8, or 9 days. Preliminary experiments determined the most effective wavelength, laser power, length of irradiation, and treatment schedule. The wavelengths examined were 361, 457, 514, 633, 720, and 1064. The laser powers and lengths of irradiation examined ranged from 8.5 to 40 mW and 13 to 120 min. Irradiation treatment was done daily, on alternating days and on the first 4 days postcrush. The most effective laser parameters for the low power treatment included daily irradiation with a helium-neon (HeNe) or argon pumped tunable dye laser a wavelength of 633 nm, with a power of 8.5 mW for 90 minutes (45.9 J, 162.4 J/cm2). The number of horseradish peroxidase (HRP) labeled neurons in the facial motor nucleus was used as an assay of the degree of regeneration. In rats in which the facial nerve was crushed but not irradiated, the average number of HRP labeled neurons in the facial nucleus was 22 on day 7 postcrush, 54 on day 8, 116 on day 9, and 1,149 on day 10. After HeNe or argon pumped tunable dye laser irradiation, the average number of HRP-labeled neurons increased to 34 on day 7 postcrush, 148 on day 8, and 1,725 on day 9. There was a statistically significant difference between the control and irradiated rats on day 9 postcrush (P < 0.01). These data indicate that transcutaneous low power irradiation with the lasers and parameters involved in this study increased the rate of regeneration of rat facial nerve following crush injury.

Postnatal histogenetic death of rat forelimb motoneurons

Previous workers have reported a five fold decrease in motoneuron numbers occurring from birth to adulthood in the rat. It has also been reported that forelimb muscles receive connections from motoneurons in both ventral horns prior to day 14 of life in the rat and that the contralateral cells subsequently degenerate completely by day 21. In the present study, postnatal changes in motoneuron number and distribution within the ventral horn were studied in the rat using the technique of retrograde horseradish peroxidase (HRP) transport following intramuscular infusion of HRP into biceps brachii (BB). Peripheral nerves other than those to BB were sectioned and ligated to control for HRP diffusion. The spatial organization of BB motoneurons was compared in animals 9-14 days old and adult animals using computer 3-D reconstruction. This allowed observations of the BB motoneurons from a variety of perspectives in relationship to a number of spinal cord landmarks and avoided the necessity for transverse and horizontal sectioning of the cords in alternate animals. A decrease of 50-75% in the number of HRP filled motoneurons number was found from birth to adulthood (adults 98-150, neonates 172-243). The spatial arrangement of the BB motoneurons with regard to the root entry zones and other landmarks such as the dorsolateral convexity of the ventral horn, remains constant from birth to adulthood. No evidence was found to support the existence of inappropriate connections from motoneurons in either the ipsi or contralateral ventral horns of neonate rats. It is suggested that the comparatively small decreases in motoneurons postnatally could be a continuation of the histogenetic processes of cell death begun in utero and is related to the postnatal development of the central and peripheral connections of motoneurons.

Electron microscopic identification of mammillary body terminals in the rats AV thalamic nucleus by means of anterograde transport of HRP. A quantitative comparison with the EM degeneration and EM autoradiographic techniques

A comparison has been made between the number of horseradish peroxidase (HRP)-labeled mammillary body terminals in the antero-ventral (AV) nucleus and the number of such terminals labeled with the electron microscopic (EM) autoradiographic [6] and EM degeneration technique [6]. With the anterograde HRP technique less terminals were labeled than with the autoradiographic technique, but more than with the degeneration technique. Furthermore it may be concluded that the anterograde HRP technique is suitable for determining the type of terminal and does not require the long exposure time of the autoradiographic technique.

Olivocochlear and vestibular efferent neurons of the feline brain stem: their location, morphology and number determined by retrograde axonal transport and acetylcholinesterase histochemistry.

Anterograde degeneration studies have shown that the cochlear and vestibular receptor organs receive an efferent innervation from neurons in the brain stem. This pathway may provide a mechanism by which the CNS could modulate its own afferent input. The neurons which provide this innervation have so far escaped positive identification with methods which depend on retrograde cell changes after axotomy. In the present study, horseradish peroxidase (HRP) was injected into the labryinths of kittens and after allowing 24 hours for the retrograde axonal transport of this tracer, its presence in neurons of the brain stem was demonstrated histochemically. Because there is evidence that the efferent innervation of the labyrinth is cholinergic, acetylcholinesterase (AChE) was also demonstrated histochemically in the same or in adjacent tissue sections. Neurons labelled with HRP were found bilaterally in most periolivary cell groups of the superior olivary complex (cochlear efferents) and in the parvocellular reticular nucleus lateral to the abducens nucleus (vestibular efferents). Counts of labelled neurons yielded estimated totals of 1,700-1,800 cochlear and 400-500 vestibular efferent neurons. Approximately 60% of the neurons in each total were located on the side ipsilateral to the injection. The distribution of HRP-labelled neurons was virtually identical to that of AChE-positive neurons found in adjacent sections, and in those regions with predominantly ipsilateral or contralateral projections, there was an approximate correspondence in number of HRP- and AChE-positive neurons. In tissue sections processed successively for demonstration of HRP and AChE, virtually all HRP-labelled neurons were found to be AChE-positive. These findings suggest that a number of current conceptions regarding labyrinthine efferent systems may need revision.