Nerve growth factor action on 2-deoxy-D-glucose transport in dorsal root ganglionic dissociates from chick embryo

Survival of BSC-1 cells through the maintenance of cell volume brought about by epidermal growth factor depends on attachment to the substratum

Addition of epidermal growth factor to culture medium without calf serum suppressed the increase in cell volume and then enhanced the survival of BSC-1 cells attached to culture dishes. However, these effects of epidermal growth factor were not observed in the case of cells on dishes coated with heat-denatured bovine serum albumin.

Effect of nerve growth factor on glucose utilization and nucleotide content of pheochromocytoma cells (clone PC12)

The effect of nerve growth factor (NGF) on the utilization and fate of uniformly labeled 14C glucose and on the content of several pyridine and purine nucleotides has been tested in the clonal cell line PC12. After incubation for 72 h with NGF, PC12 cells exhibit a 2.7-fold increase in glucose utilization and a 4.7-fold increase in CO2 release. During the same incubation period, all the nucleotides tested (NAD+, AMP, GMP, UDP-glucose, UDP-galactose, UDP, ADP, GDP, UTP, CTP, ATP, and GTP) underwent significant increments, varying from a minimum of 27% for ADP to a maximum of 90-120% for AMP, GMP, UDP-glucose, and UDP-galactose. These findings are discussed in connection with the trophic and differentiative effects of NGF in PC12 cells, which, in the presence of this factor, shifted from a neoplastic to a neuronal-like cell population.

Regulation of deoxyglucose uptake by adrenocorticotropic hormone in cultured neurons

The influence of ACTH and some of its N-terminal related peptides was investigated on the uptake of (3H)-2-deoxy-D-glucose in pure cultures of neurons from chick embryo cerebral hemispheres. ACTH influences deoxyglucose uptake in a time and dose-dependent fashion. The stimulation of deoxyglucose uptake is observed after a delay of 6-8 h and requires active protein synthesis. ACTH does not affect deoxyglucose in non-neuronal cells (astroglial cells, hepatocytes, myoblasts, fibroblasts). The effect of various peptide hormones, neuropeptides and growth factors, active in the central nervous system or other tissues, has also been examined. None of these were able to stimulate deoxyglucose uptake, suggesting that the regulation of hexose uptake in neurons is specific for the ACTH-related peptides.

Effects of growth hormone and triiodothyronine administration of the localization of 14C-D-glucose on regenerating sciatic nerve in rabbits

In the present study the effect of the administration of GH and T3 on glucose distribution in the regenerating nerve was studied. The right sciatic nerve of 40 male rabbits was crushed at a specific site so that axonotmesis ensued. The animals were divided into two equal groups: one for the study of the effects of human growth hormone (hGH) and the other of triiodothyronine (T3). In all animals 14C-D-glucose a([14C]D-G) was injected iv as a tracer. The sciatic nerves from both sides were removed from all animals, divided into four equal segments and checked for radioactivity. In all cases an increased concentration of [14C]D-G appeared in the crushed nerve as compared with the intact one. GH administration caused a decrease in [14C]D-G uptake in both intact and injured nerves. T3 administration caused a significant decrease in [14C]D-G levels in the blood but did not substantially change [14C]D-G uptake in the crushed nerves as a whole. T3 administration appeared also to cause a peripheral displacement of the site of maximum [14C]D-G concentration in the injured nerve, indicating possibly an increased regeneration rate.

Interchangeability of nerve growth factor and high potassium in the long-term survival of chick sympathetic neurons in serum-free culture medium

The results of the present experiments demonstrate that embryonic sympathetic neurons initially selected in culture by nerve growth factor could be subsequently supported by raising potassium concentration of the medium to 35 mM. Alternatively, neurons initially selected by 35 mM potassium could be supported in a normal culture medium but supplemented with nerve growth factor. It is concluded that nerve growth factor and high concentrations of potassium act on the same subpopulation of chick embryonic sympathetic neurons to promote their long-term survival in a serum-free culture medium.

Nerve growth factor-induced stimulation of alpha-aminoisobutyric acid uptake in PC12 cells: relationship to plasma membrane receptor occupancy

Nerve growth factor (NGF) stimulates the uptake rate of the nonmetabolized amino acid alpha-aminoisobutyric acid (AIB) in the clonal PC12 pheochromocytoma cell line by 40-70%. This effect reaches a maximum after a 1-hour incubation with the hormone and then drops over 50%, reaching a minimum after 4 hours of NGF administration. Longer exposure to the hormone leads to a gradual rise in stimulation, and by 24 hours, the cells regain about 80% of the original 1-hour rate. Results of NGF-binding studies indicate that stimulation of AIB uptake follows closely behind the amount of NGF bound to the low-affinity NGF receptors. Dose-response experiments indicate that full stimulation occurs biphasically. Within the NGF concentration range of 0.1 ng/ml to 1 ng/ml, the AIB uptake rate is 30% of the maximum 1-hour response. At 2.5 ng/ml NGF, the stimulation jumps to about 75% maximal response while 100% response is reached between 5 ng/ml and 50 ng/ml NGF. We suggest that the two states of the NGF plasma membrane receptor on PC12 cells may both be involved in mediating NGF stimulation of AIB uptake.

Nerve growth factor-induced stimulation of alpha-aminoisobutyric acid uptake in PC 12 cells: evaluation of its biological significance

In the clonal PC12 pheochromocytoma cell line, the observed effects of nerve growth factor (NGF) on the uptake rates of alpha-aminoisobutyric acid (AIB) depend upon the assay conditions employed. In orthodox uptake assays calling for serum removal prior to the addition of AIB, 50 ng/ml NGF causes a stimulation of uptake of 62% after 40 minutes and 46% after 24-hours exposure. However, serum stimulates AIB uptake to a similar extent and the effects of serum and NGF are not additive. An uptake assay which directly measures the AIB uptake experienced by PC12 cells undergoing NGF-induced morphological differentiation was therefore employed. When compared with control cells growing in serum-containing medium, NGF-induced differentiating PC12 calls experience (1) only a transient and modest increase in AIB uptake, and (2) a significant long-term decrease in AIB uptake under conditions optimal for differentiation. It is concluded that NGF-directed neurite outgrowth is not mediated by NGF effects on amino acid uptake via the A-system.

Maintenance by nerve growth factor of the intracellular sodium environment in spinal sensory and sympathetic ganglionic cells

A promising advance in our understanding of the mode of action of nerve growth factor (NGF) has been provided by our recent finding that dissociated cells from 8-day embryonic chick dorsal root ganglia (DRG) lose their competence to maintain a low intracellular Na+ when incubated without NGF for 6 h, and promptly recover it on delayed presentation of NGF. To ascertain whether control of intracellular Na+ is a general feature of the NGF action on its target neurons, we have now tested several NGF-sensitive tissues, both as intact ganglia and dissociates, for their ability to (i) accumulate large amounts of 22Na+ over a period of hours in the absence of NGF, and (ii) rapidly extrude the accumulated radioactivity upon delayed presentation of NGF. Intact and dissociated chick embryo DRG and sympathetic ganglia, as well as dissociated mouse DRG, displayed the expected Na+ responses to the lack or the administration of NGF. No such responses were observed with intact mouse DRG, which do not require NGF in explant cultures for neuritic outgrowth, or with intact and dissociated chick embryo ciliary ganglia, which are not sensitive to NGF in either explant or dissociated cell cultures. Thus, in all ganglionic preparations examined, the occurrence of Na+ responses to exogenous NGF correlated with traditional responses to NGF in culture. This together with other recent data, reinforces the view that ionic control may be a critical element in the mechanism of action of NGF.

Sodium dependence of the nerve growth factor--regulated hexose uptake in chick embryo ganglionic cells

Embryonic dorsal root ganglionic cells, when incubated in vitro in the absence of nerve growth factor (NGF) undergo a general metabolic degeneration which is preceded by certain changes in permeation properties. Previous studies demonstrated that NGF can rapidly modulate permeation properties which regulate the availability to the cell of an important energy source, glucose. Hexose uptake was determined by measuring the ability of the cells to accumulate [3H]labeled 2-deoxy-D-glucose. The work reported here shows that the NGF-dependent portion (about one-third) of the total specific hexose uptake was also dependent on the presence of Na+, with the apparent uptake constant (Kt) for deoxyglucose varying inversely with an external Na+ concentration of 70-140 mM; Vmax was unaffected in this range. Preincubation of ganglionic cells with 10 mM ouabain for 15-60 min, followed by a pulse with [3H]-deoxyglucose, also resulted in 50-95% reduction of the NGF-sensitive uptake. A similar pretreatment of cells with veratridine gave a 25-50% reduction in uptake. The NGF-controlled hexose uptake was also energy dependent, being diminished 50-95% after a 30-90 min preincubation with 2 mM 2,4-dinitrophenol. Uptake activities for other substrates (alpha-aminoisobutyric acid, uridine) which exhibited NGF regulation were likewise Na+-sensitive. These results indicate that availability of major energy substrates to NGF-dependent dorsal root ganglionic neurons is controlled by sodium gradients across their membranes. It is conceivable that NGF provides for maintenance and development of its target neurons by acting on such sodium gradients and, consequently, regulating the intake of essential nutrients.