Glial cells execute essential functions in central nervous system (CNS) development and are also believed to play important roles during gliosis in response to trauma or disease. These developmental and pathological states have also been associated with elevated expression of opioid genes. Because levels of the cytokine interleukin-1 beta (IL-1 beta) increase following CNS lesions, we examined the possible influence of IL-1 beta on the expression of opioid genes in astrocytes cultured from rat cortex. Proenkephalin mRNA expression was stimulated by IL-1 beta in a time- and concentration-dependent manner, being maximal with 5 U/ml IL-1 beta at 4 h. Although the beta-adrenergic agonist isoproterenol was also active, interferon, glutamate, and carbachol were not. Unlike isoproterenol, the actions of IL-1 beta were not associated with a cyclic adenosine monophosphate (AMP)-dependent pathway. Interleukin-1 beta also regulated a proenkephalin-chloramphenicol acetyltransferase fusion gene transiently transfected into astrocytes, with a dose-response similar to that active in proenkephalin mRNA. These effects of IL-1 beta were region-specific, not being observed with either cerebellar or hippocampal astrocytes; however, isoproterenol was active in the latter cell populations. Proenkephalin mRNA in cortical astrocytes was stimulated following a temperature stress. These results suggest that enhanced proenkephalin gene expression in astrocytes by IL-1 beta may be important in neuroimmune interactions and in trauma-induced CNS injury or stress.
Rat brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) were engineered for expression in a baculovirus-infected Spodoptera frugiperda insect cell system . The BDNF and NT-3 from the culture supernatants were purified by ion-exchange and reverse-phase chromatography to apparent homogeneity . The purification procedure yielded^-2 mg of pure rat BDNF or NT-3 per liter of culture supernatant . A single N-terminus only was found for either secreted molecule and was analogous to that predicted from the corresponding cDNA sequence . The recombinant neurotrophins obtained were also homogeneous with regard to molecular weight and amino acid sequence . In their native conformation, the insect cell-produced rat BDNF and NT-3 molecules were homodimers consisting of 119 amino acid polypeptide chains . Thus, although the genes transfected into the S . irugiperda cells coded for proBDNF or proNT-3, the BDNF and NT-3 recovered after purification were >95% fully processed, mature protein . Mature recombinant rat BDNF and NT-3 were found not to be significantly glycosylated . Pure, recombinant rat BDNF and NT-3 promoted the survival of embryonic dorsal root ganglion neurons in the low picomolar range . Because recombinant rat BDNF and NT-3 can be obtained in large quantities, purified to near homogeneity, and are identical in amino acid sequence to the corresponding human proteins, they are suitable for evaluation in animal models . Key Words : Brain-derived neurotrophic factor-Neurotrophin-3-Baculovirus-Purification-Rat . J . Neurochem. 62, 471-478 (1994) .The development and maintenance of the vertebrate nervous system depends on neuronal survival proteins known as neurotrophic factors (Snider and Johnson, 1989) . Nerve growth factor (NGF) was the first neurotrophic molecule demonstrated to be required for normal development, particularly in the PNS (Levi-Montalcini, 1987) . That NGF maintains the survival of only certain neuronal subtypes suggests that there exist additional molecules with distinct specificities that fulfill the role of target-derived, retrogradely transported neurotrophic factors . Indeed, brain-derived neurotrophic factor (BDNF) 471
The ability of nitrilotriacetic acid (NTA) to induce aneuploidy was studied in the germ line of both Drosophilu and the mouse. The Free Inverted X Chromosomes (FIX) genetic system, adopting a brooding scheme, was used to detect induced aneuploidy in Drosophil~, and a cytogenetic method based on chromosomal counting in secondary spermatocytes was used in the mouse.In Drosophilu a highly significant (P < 0.001) increase of aneuploidies was produced by NTA (5 X M), which was greater than that produced by colchicine (7.5 X M) and 5-fluorodeoxyuridine M), which were used as positive controls. Brooding effects were observed with NTA, which produced a maximum induction of chromosomal gain in brood I, suggesting a possible stage-specific action during meiosis. The ability of NTA (275 mglkg body weight) to induce meiotic aneuploidy (hyperhaploidy) also was confirmed in the mouse (P < 0.001), where all the aneuploidies detected were attributable to treatment of the metaphase I stage.
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