Bo Bjerre

A study of the de- and regenerative changes in the sympathetic nervous system of the adult mouse after treatment with the antiserum to nerve growth factor

In the adult mouse, the antiserum to nerve growth factor (NGF) induced marked atrophic changes of the ganglionic cell bodies in the superior cervical ganglion (SCG) and a disappearance of adrenergic nerve terminals in several peripheral tissues. By fluorescence histochemistry a lower-than-normal content of the noradrenaline (NA) transmitter was observed within the entire adrenergic neurone only 1 day after a single injection of NGF-antiserum (0.1 ml/g body weight). An atrophy of adrenergic nerve cell bodies and a disappearance of adrenergic nerve terminals were observed after 3 days, but the antiserum-induced effects did not appear maximally developed until 7 days after treatment. These fluorescence histochemical findings were paralleled by a gradual decrease of the endogenous NA levels in peripheral tissues and also of the weight of the SCG. A gradually proceeding restoration towards normal of the adrenergic innervation apparatus was observed fluorescence histochemically following a 5-day treatment with NGF-antiserum (0.1 ml/g body weight each dose), and after 6 weeks to 3 months a normal or close to normal fluorescence microscopical appearance was regained in the peripheral tissues and also in the SCG. These findings were parelleled by the results of the determinations of endogenous NA in peripheral tissues and by the results of weighing the SCG. We discuss some important differences between NGF-antiserum and 6-hydroxydopamine with respect to their mode of action on the mature sympathetic nervous system. Finally, we suggest that a decreased availability of NGF in a terminal area, due to an interference with endogenous NGF by NGF-antibodies, may temporarily result in an impaired function of the supplying adrenergic neurone, including a degeneration of nerve terminals.

Stimulation of growth of new axonal sprouts from lesioned monoamine neurones in adult rat brain by nerve growth factor

Abstract A strong stimulating effect of intraventricularly administered NGF proteins has been demonstrated on the growth of new axonal sprouts from lesioned central catecholamine and indolamine neurones in the adult rat. The effect was observed as an increase in the growth of the lesioned ascending noradrenaline, dopamine, and indolamine neurone systems into a denervated iris transplanted to the caudal diencephalon. The response was similar with high molecular (7S) and low molecular (2.5S and the β-subunit of 7S NGF) NGF preparations, and it was dose-dependent. The results suggest that NGF, given as a single injection at the time of transplantation and axonal lesioning, did not alter the time sequence of events in the growth process (i.e. the time necessary for the initiation of sprouting) but rather that it accelerated or potentiated the outgrowth of the new axonal sprouts during the time when it normally occurred. It is suggested that the NGF sensitivity of regenerating central noradrenaline, dopamine, and indolamine neurones might reflect a general dependence of these neurones on endogenous NGF during ontogenesis and regeneration.

Axonal regeneration of peripheral adrenergic neurons: Effects of antiserum to nerve growth factor in mouse

SummaryThe effect of the antiserum to Nerve Growth Factor (NGF) on the regrowth of adrenergic axons following 6-hydroxydopamine-(6-OH-DA)induced axotomy was investigated in the mouse using fluorescence histochemistry and determinations of endogenous NA. A single subcutaneous injection of 0.1 ml/g of anti-NGF serum, given one day after the 6-OH-DA-injection (60 mg/kg), caused a pronounced inhibition of the regeneration of the adrenergic axons in all peripheral tissues investigated (iris, salivary glands, heart, intestine, spleen and pancreas). The ganglionic cell bodies in the superior cervical ganglion underwent a marked atrophy, as observed 5 days and 3 weeks after the 6-OH-DA treatment, but they had regained normal appearance after 2 months. Furthermore, the fluorescence histochemistry revealed an antiserum-induced reduction of the NA content in all parts of the regenerating neurons, except for the most distal portions of the surviving axon stumps. At 5 days and 3 weeks after the 6-OH-DA-treatment the sprouting and regrowth of the adrenergic axons were much reduced in the anti-NGF serum-treated animals. When compared with those of the corresponding controls, the NA levels in the anti-NGF serum-treated specimens were only 20–40% at 3 weeks. The anti-NGF serum-induced inhibition was temporary, and between 3 weeks and 2 months after treatment the regeneration in the antiserum-treated animals started to catch up with the controls. The results indicate that endogenous NGF or NGF-like substances may play a role in the process of regeneration of lesioned sympathetic neurons in the adult animal. They also suggest that mature sympathetic neurons during regeneration resume the high sensitivity to, and dependence on, NGF, which otherwise are characteristic of sympathetic neurons during their ontogenetic growth and development.

Inhibition of the regenerative growth of central noradrenergic neurons by intracerebrally administered anti-NGF serum

The regenerative growth of central monoamine neurons in the adult rat brain, into an autologous iris transplant placed in the caudal diencephalon, was studied. One injection of 2 μl of anti-NGF serum, given intracerebrally close to the ascending noradrenergic axons from the locus coeruleus, caused a marked reduction in the regrowth of new axonal sprouts into the transplant, as observed 2 weeks after operation. The inhibitory effect was pronounced when the injection was given at the time of transplantation (which was also the time of axonal damage), and it was considerably less effective when given 4 days after the transplantation,i.e. at a time when the sprouting from the lesioned axons had already started. A similar inhibition of the regrowth of the lesioned noradrenergic locus coeruleus axons was also obtained after preincubation of the iris transplant in the anti-NGF serum. In contrast, the regrowth from the lesioned dopamine and indolamine fibers in the medial forebrain bundle system seemed unaffected. None of the inhibitory effects was seen in the control specimens treated with different types of control sera. This indicates that the observed impairment of the formation and regrowth of new axon sprouts from lesioned central noradrenergic neurons was the result of a specific action of the NGF-antibodies by an interference with NGF (or an NGF-like substance) in the brain tissue and/or in the transplanted iris tissue. These observations point to a possible role of endogenous NGF, or an NGF-like substance, in adult central noradrenergic neurons during regeneration.

A stimulatory effect by nerve growth factor on the regrowth of adrenergic nerve fibres in the mouse peripheral tissues after chemical sympathectomy with 6-hydroxydopamine

SummarySystemically administered Nerve Growth Factor (NGF) had a strong stimulating effect on the regeneration of fully developed adrenergic neurons in the peripheral tissues of the mouse after axotomy induced by 6-hydroxydopamine. The NGF stimulation was investigated at 9 and 21 days after the 6-hydroxydopamine injection, and was observed fluorescence histochemically as an increase in number, length, and thickness of the outgrowing adrenergic fibre bundles, in the extent and abundance of the terminal ramifications of the regrowing fibres, and in their fluorescence intensity. This increase in the regrowth of the lesioned adrenergic axons was paralleled by strong and significant increases in the recovery of endogenous noradrenaline in several peripheral tissues. The present findings demonstrate a sensitivity of fully developed adrenergic neurons to NGF during axonal regeneration, and it is suggested that NGF might play a normal physiological role in this process.

HAS NERVE GROWTH FACTOR A ROLE IN THE REGENERATION OF CENTRAL AND PERIPHERAL CATECHOLAMINE NEURONS

Publisher Summary This chapter describes the role of nerve growth factor (NGF) in the regeneration of central and peripheral catecholamine neurons. Axonal regeneration can be understood as the attempt of a neuron to re-establish axonal connections severed by a lesion. This process implies a series of complex events involving the reaction of the cell body to the injury, the formation of new axonal sprouts, the outgrowth of the new sprouts, and finally, the establishment of new synaptic connections. The effects of exogenous NGF and of anti-NGF serum were tested on the process of regeneration after axonal degeneration induced by 6-OH-DA. In the adult animal, 6-OH-DA in low to moderate doses is known to induce a selective degeneration of the terminal and paraterminal axon parts of the sympathetic neurons, and therefore this drug offers a very useful tool for reproducible and widespread lesioning of peripheral adrenergic axons. In most of the studied organs, the NGF treatment caused a marked stimulation of the axonal regeneration, as observed at both 9 and 21 days after the 6-OH-DA-induced axonal damage.

Effects of nerve growth factor and its antiserum on axonal regeneration of short adrenergic neurons in the male mouse

SummarySystemically administered Nerve Growth Factor (NGF) had a weak stimulatory effect and the antiserum to NGF a marked inhibitory effect on the regeneration of so-called short adrenergic neurons in the accessory genital organs of 5-week old male mice after chemical sympathectomy induced by 6-hydroxydopamine. The NGF-induced effect was investigated 9 days after the 6-hydroxydopamine-injection and was observed fluorescence histochemically, particularly in the accessory genital glands, but not biochemically in the vas deferens. The strong impairment of the regrowth of the short adrenergic neurons caused by anti-NGF serum-treatment was observed fluorescence microscopically as an almost complete inhibition of the regeneration in the different accessory genital organs up to 3 weeks after the 6-hydroxydopamine-treatment. The inhibition was only temporary, however, and 2 months after 6-hydroxydopamine, the extent of the regrowth of the short adrenergic neurons was in all respects similar in anti-NGF serum-treated and control animals. These microscopical observations were paralleled by the fluorometric determinations of the endogenous NA levels in the vas deferens. Compared with the effects of NGF and its antiserum on the regeneration of the so-called long adrenergic neurons, similar, but overall less pronounced effects were noted on the regrowth process of the short adrenergic neurons. Possible explanations for the different reactions of the two types of neurons to NGF and its antibody are discussed. The present findings may suggest, that NGF has a normal physiological role during regeneration—when the neurons resume ontogenetic features—of short adrenergic neurons, although it has not been proved that NGF is of importance during the ontogenetic growth and development of this type of neurons.

NGF IN MAINTENANCE AND REGENERATION OF ADRENERGIC AXONS

Publisher Summary This chapter discusses the role of nerve growth factor (NGF) in maintenance and regeneration of adrenergic axons. There is considerable evidence that nerve growth factor plays an important role in the ontogenetic growth and the development of sympathetic adrenergic neurons. The morphological alterations induced by the anti-NGF serum treatment in the adrenergic terminals, and the time course of these changes, strongly suggest that besides a reduction in neuronal NA content, the antiserum treatment causes an actual degeneration of nerve terminals. There is much to indicate that the NGF-sensitivity of adrenergic neurons changes quantitatively and also qualitatively during the first few weeks of life, which coincides with the time of maturation of the sympathetic nervous system in the mouse. Whereas in the chick embryo and the newborn mouse, NGF has been reported to induce an increase both in size and number of adrenergic ganglion cell bodies, there is probably only a hypertrophic response of the adrenergic cell bodies in the adult. In most of the peripheral tissues, innervated by both para- and prevertebral sympathetic chain ganglia, the NGF treatment caused a marked stimulation of the axonal regeneration, as observed at both 9 and 21 days after the 6-OH-DA induced axonal damage.

Effect of mouse submaxillary gland and NGF preparations on competent chick ectodermin vitro, studied by the immunofluorescence method

SummaryThe submaxillary gland of the male mouse, but not the female, was shown to act strongly neuralizing on competent chick ectoderm, recorded as frequency of neural antigen producing cultures. NGF preparations from mouse submaxillary gland were shown to cause a high frequency of neural antigen producing cultures. The effect of the NGF preparations diminished with time and ceased after storage at −90° C for 17 days. The possible role of NGF in the present system is discussed; but the possibility could not be excluded that factors other than NGF present in the submaxillary gland and the NGF preparations cause the competent ectoderm to neuralize.