The electrical activity of neurons is known to play a role in neuronal development, as well as repair of adult nervous tissue. For example, the extension of neurites and motility of growth cones can be modulated by changes in the electrical firing of neurons. The vitamin A metabolite retinoic acid also plays a critical role during nervous system development and is also known to elicit regenerat...

Several recent studies have shown that retinoic acid signalling is required for correct patterning of the hindbrain. However, the data from these studies are disparate and the precise role of retinoic acid signalling in patterning the anteroposterior axis of the neural tube remains uncertain. To help clarify this issue, we have cultured a staged series of chick embryos in the presence of an ant...

The discovery of the biological activity of 9-cis-retinoic acid raises questions as to its mode of biosynthesis. A simple mechanism involves the direct isomerization of all-trans-retinoic acid to 9-cis-retinoic acid. It is shown here that bovine liver membranes, but not supernatant fractions, can isomerize all-trans-retinoic acid into 9-cis-retinoic acid and 13-cis-retinoic acid. The concentrat...

Binding affinities of retinoic acid and its synthetic analogues to intracellular retinoic acid-binding protein, which is a possible candidate for mediating their biological function, and to serum albumin, the plasma transport protein, were evaluated. A quantitative method involving elimination of interfering serum albumin by immunoprecipitation was developed to measure the binding efficiency of...

BACKGROUND Retinoic acid is implicated in the induction of the gene encoding Sonic hedgehog (Shh) that specifies anteroposterior positional values and promotes growth of the developing limb bud. However, because retinoic acid is involved in limb initiation, it has been difficult to determine if it could have additional roles in anteroposterior patterning. To investigate this, we implanted retin...

In the chick limb bud, the zone of polarizing activity controls limb patterning along the anteroposterior and proximodistal axes. Since retinoic acid can induce ectopic polarizing activity, we examined whether this molecule plays a role in the establishment of the endogenous zone of polarizing activity. Grafts of wing bud mesenchyme treated with physiologic doses of retinoic acid had weak polar...

Retinoic acid, retinol, retinyl acetate, and retinal induced activities of lysosomal enzymes, such as lysozyme, acid protease, and acid phosphatase, in mouse myeloid leukemia cells (M1), while the pyridyl analog of retinoic acid had no effect. Retinoic acid was the most potent inducer of lysosomal enzyme activities. The induction of lysozyme activity by retinoic acid was inhibited by treatment ...

1. The formation in vivo of retinoic acid from microgram quantities of intrajugularly administered [15-(14)C]retinol was demonstrated in the rat. 2. Endogenously formed retinoic acid (about 0.1mug./rat) was found in liver, and to a much smaller extent in intestine, 12hr. after retinol administration. 3. Excretion of some of the endogenously formed retinoic acid occurred in the bile of bile-duct...

A retinoic acid epoxidase is present in rat kidney homogenates. It is found in the particulate fraction, and is dependent on ATP, NADPH, and oxygen. It is stimulated by Fe2+ and inhibited by Mn2+, Zn2+, Cu2+, EDTA, and N,N'-diphenyl-para-phenylenediamine. Its properties are closest to those of microsomal lipid peroxidases previously studied. Epoxidase activity is not affected by the rat's vitam...

The metabolism of C3H]retinoic acid, both in uiuo and in vitro in a 10,000 X g supernatant preparation of small intestinal mucosa and liver of vitamin A-deficient hamsters, has been shown to be dependent upon pretreatment of the hamsters with retinoic acid. A proportional increase in both the in uiuo and the in vitro metabolism in the intestine and liv’er was found with inducing levels of retin...