Characteristics of labelled RNA from spinal ganglia of chick embryo and the action of a specific growth factor (NGF)

Expression of Nerve Growth Factor in Itchy Skins in Atopic NC/NgaTnd Mice

Although the possible involvement of neurotrophic factors in itchy skins of atopic dermatitis has been predicted, the exact mechanism by which itch is induced remains unclear. Since nerve growth factor (NGF) has crucial effects on development and functions of sensory nerves, we determined production of NGF and extension of nerve fibers in skins of NC/NgaTnd mice with or without atopic dermatitis. NC/NgaTnd mice spontaneously develop atopic dermatitis-like skin lesions when they are raised in air-unregulated conventional circumstances. We quantified scratching behavior of NC/NgaTnd mice during the development of dermatitis using a novel analytical system and compared to clinical skin severity scores. A significant correlation between the severity of dermatitis and the increase in the number of scratches was identified, indicating that scratching behavior may associate with clinical skin conditions. NGF contents in the skin lesions of conventional NC/NgaTnd mice were significantly higher than those in SPF mice. Positive reactions for NGF were observed in keratinocytes and fibroblasts in affected skins of conventional NC/NgaTnd mice. Immunohistochemical analysis showed the extension of protein gene product 9.5-positive nerve fibers from the dermis toward the epidermis at the skin lesions. These results suggest that sensory nerves induced by NGF may contribute to development of itch, and that NGF produced at the affected site may provide abnormal skin sensitivity in atopic dermatitis.

An autocrine function of nerve growth factor for cell cycle regulation of vascular endothelial cells

Nerve growth factor (NGF) regulates maintenance, survival, and function of not only neuronal cells but also various kinds of non-neuronal cells. Here we clearly demonstrated that mouse aortic endothelial cells (AEC) produced bioactive NGF, and the production was enhanced by a proinflammatory cytokine, interleukin (IL)-1beta. AEC expressed both high affinity (TrkA) and low affinity (p75(NGFR)) receptors for NGF. Exogenously added NGF induced rapid phosphorylation of TrkA tyrosine kinase. Addition of anti-NGF neutralizing antibody resulted in an increase in the proportion of AEC in S and G(2)/M phases and in a hypodiploid range. Since the vascular endothelium plays a pivotal role in inflammatory conditions, these results strongly suggest that NGF, whose production is enhanced at the affected site, may contribute to maintenance, survival, and function of vascular endothelial cells by autocrine and/or paracrine mechanisms.

Sterol-like compound from sensory ganglia. Effect of a nerve growth factor and insulin on its biosynthesis

1. Sensory ganglia from 8-day-old chick embryos were incubated with a specific nerve growth factor and with insulin. 2. From the total lipid extract of the ganglia a compound with steroid characteristics was isolated. 3. The synthesis of this compound, measured spectrophotometrically, diminished after addition of the nerve growth factor and insulin to the incubation medium. 4. The incorporation of sodium [2-(14)C]acetate and dl-[2-(14)C]mevalonic acid into total lipids of the sensory ganglia was stimulated by the nerve growth factor and insulin, but the radioactivity of the sterol-like compound was slightly lower. The incorporation of labelled mevalonic acid either into total lipids or into the sterol-like compound was about 25% lower. 5. About 20% of the acetate incorporated into total lipids and about 87% of the mevalonic acid were recovered in the sterol-like compound.