Stimulation of DNA synthesis in Balb/c 3T3 cells by peripheral nerve degenerating in vitro

Cell proliferation inhibition in remitting multiple sclerosis CSF

Sixty percent of the CSF samples from 21 multiple sclerosis (MS) patients in remission inhibited cellular proliferation of a variety of neuronal and glial cell lines. No inhibition was observed with CSF from relapsing or progressive MS patients (0/19). Two of 82 samples from stationary MS patients were positive. No inhibition was found in MS sera. The CSF samples had no effect on myelination of mouse organotypic cerebellar cultures. Like MS cellular proliferation and subsequent lesion formation, the 'deactivation' of the lesion also is an active defined process, rather than just the cessation of the immunological events. Furthermore, approximately 20% of samples from Huntington's, Alzheimer's and Parkinson's disease patients were also positive. However, no inhibition was seen in CSF from amyotrophic lateral sclerosis patients or controls.

Effects of growth hormone treatment on the regeneration of rat sciatic nerve

The effect of human growth hormone (hGH) on regeneration of neuronal tissue have been studied in rats. A crush lesion was made on the sciatic nerve at the thigh level in intact or hypophysectomized rats. The hGH was administered systemically via subcutaneously implanted miniosmotic pumps. Regeneration was evaluated by the 'pinch-test' after 3, 4 and 6 days. Regeneration was significantly (P less than 0.05) impaired in hypophysectomized rats, but restored to normal after treatment with hGH (200 mIU/day). In intact rats treatment with 400 mIU/day hGH significantly (P less than 0.05) stimulated regeneration, whereas no effect was observed at 200 mIU/day. Immunoreactive insulin-like growth factor 1 (IGF-1) decreased in hypophysectomized rats, but rose again after hGH treatment. However, no consistent correlation between circulating IGF-1 and the rate of regeneration was found. Our results show that hGH can increase the rate of regeneration in peripheral nerves after injury. This can be due either to direct effects of hGH or to indirect effects via locally produced growth factors (e.g. somatomedins).

A new method for studies of the effects of locally applied drugs on peripheral nerve regeneration in vivo

An in vivo technique which allows local application of drugs to the regenerating rat sciatic nerve for several days is presented. The sciatic nerve was transected at the knee level and a crush lesion was made proximal to the transection. The crush lesion and the nerve segment distal to it was enclosed in a chamber made of silicone tubing (STC). The STC was perfused via a catheter connected to a miniosmotic pump. Regeneration was evaluated with the 'pinch-test' at 3, 4 and 6 days after the enclosure of the nerve. The rate of regeneration in the STC-surrounded nerve segment was 3.5 mm/day after an initial delay of 1.6 days which are values similar to those in uncovered nerves with crush lesions. Perfusion of the STC with either vinblastine, cycloheximide, actinomycin D or mitomycin C inhibited regeneration. The effects were confined to the STC-covered region. Leakage of drugs was too small to affect the nerve outside the chamber. The results suggest that regeneration requires proliferation and protein synthesis in the cells surrounding the growing axons. This technique could be useful for studies of the local effects of various drugs, specific antibodies, potential growth factors etc. on regeneration of peripheral nerves.

Distribution of fibroblast growth factor in the central and peripheral nervous systems of various mammals

Fibroblast growth factor (FGF) is a potent, mesodermal cell mitogen which has been identified throughout the central nervous system of various mammals and shown to display no regional concentration differences within the brain. An FGF-like mitogen of similar specific activity is also identified in the peripheral nervous system. Although not myelin-derived, these factors may arise from some component, of neuronal or glial origin, common to the central and peripheral nervous systems.

Serotonin binding sites. I. Structures of sites on myelin basic protein, LHRH, MSH, ACTH, interferon, serum albumin, ovalbumin and red pigment concentrating hormone

We report the results of nuclear magnetic resonance spectroscopy studies of combinations of serotonin (5-hydroxytryptamine) with the tryptophan peptide sequence and similar peptides from myelin basic protein. The binding site appears to consist of the sequence Arg Phe Ser Trp. Similar serotonin binding sites were found to exist on LHRH (Tyr Ser Trp) and MSH-ACTH tetrapeptide (Phe Arg Trp). These binding sites are specific to serotonin as is demonstrated by lack of binding by dopamine, histamine, acetylcholine and a dozen other pharmacologically active amines and indoles. Drugs known to affect serotonin levels, e.g., fenfluramine and L-DOPA, bind weakly to these sites. Structural and functional similarities between the tryptophan peptide, LHRH, and MSH-ACTH with an ACTH-like peptide of human leukocyte interferon, with human and bovine serum albumin, hen ovalbumin, and with red pigment concentrating hormone suggest that the latter peptides may also contain similar serotonin binding sites. The elucidation of serotonin binding sites on these peptides and proteins has implications for understanding various aspects of cancer, autoimmunity, neurological disease, and peptide hormone control.

Injury to nerves and the initiation of amphibian limb regeneration

The possibility has been investigated that nerves, which promote mitotic activity during the growth phase of limb regeneration, may also release factors upon injury to stimulate the cellular events during the initiation of regeneration. These events have been compared in control, innervated limb stumps and in limbs denervated for various periods before amputation. Wound closure occurred in an essentially normal manner in limbs denervated at the time of amputation but frequently occurred at reduced rates or not at all in limb stumps denervated 5 days before amputation. Tissue loss and various degrees of morphological regression were seen in many of the predenervated limb stumps, including all of those denervated for 6 days or more before amputation. Evidence is presented which suggests that regression may result from a combination of the denervated state and disturbance to the limb's vascular system. Limbs predenervated 2-10 days before amputation were fixed 7 days after amputation and examined histologically. All limb stumps, including those involved in regression, showed tissue dissociation and cellular dedifferentiation. Autoradiography revealed that the dedifferentiation involved DNA synthesis in both denervated and innervated limbs. Seven days after amputation, DNA-labeling indices in limb stumps predenervated 2 or 4 days were similar to those of control limbs, but labeling indices were significantly reduced in limbs predenervated 6 or more days. The results are assessed in light of the state of nerve degeneration in the limbs at the time of amputation and are discussed in terms of what is known regarding nerve-derived growth-promoting substances.

Cancer basic protein: a cellular growth factor in cancer cells?

Cancer basic protein possesses amazingly similar, but not identical, properties to myelin basic protein. Because of these similarities a theory is presented that cancer basic protein is a cellular growth factor and is intricately involved in the abnormal growth processes occurring in cancer cells.

Mitogenic effect of myelinated vs unmyelinated garfish nerve extracts

Mitogenic activities in crude extracts of unmyelinated olfactory nerves and myelinated trigeminal nerves of the garfish Lepisosteus osseus were compared. Extracts of each nerve type were added in a range of protein concentrations to serum-starved, subconfluent cultures of BALB/c 3T3 cells. At low protein concentrations (50-250 micrograms/ml) myelinated nerve extracts produced more [3H]thymidine incorporation in the cultured cells than unmyelinated nerve extracts, while at higher concentrations (500-1000 micrograms/ml), the latter caused as much DNA synthesis as the myelinated nerve extracts, surpassing them at the highest concentrations tested. The results suggest that both axonal and myelin components contribute to the growth-promoting activity in nerve tissue.