PubMed · 1735663
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E Kole, A Pugliese, B A Cunha. 1992. Meningococcal conjunctivitis.. https://pubmed.ncbi.nlm.nih.gov/1735663/
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Neurocircuit inhibition of hypothalamic paraventricular nucleus (PVN) neurons controlling hypothalamo-pituitary-adrenocortical (HPA) activity prominently involves GABAergic cell groups of the hypothalamus and basal forebrain. In the present study, stress responsiveness of GABAergic regions implicated in HPA inhibition was assessed by in situ hybridization, using probes recognizing the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD65 and GAD67 isoforms). Acute restraint preferentially increased GAD67 mRNA expression in several stress-relevant brain regions, including the arcuate nucleus, dorsomedial hypothalamic nucleus, medial preoptic area, bed nucleus of the stria terminalis (BST) and hippocampus (CA1 and dentate gyrus). In all cases GAD67 mRNA peaked at 1 hr after stress and returned to unstimulated levels by 2 hr. GAD65 mRNA upregulation was only observed in the BST and dentate gyrus. In contrast, chronic intermittent stress increased GAD65 mRNA in the anterior hypothalamic area, dorsomedial nucleus, medial preoptic area, suprachiasmatic nucleus, anterior BST, perifornical nucleus, and periparaventricular nucleus region. GAD67 mRNA increases were only observed in the medial preoptic area, anterior BST, and hippocampus. Acute and chronic stress did not affect GAD65 or GAD67 mRNA expression in the caudate nucleus, reticular thalamus, or parietal cortex. Overall, the results indicate preferential upregulation of GAD in central circuitry responsible for direct (hypothalamus, BST) or multisynaptic (hippocampus) control of HPA activity. The distinct patterns of GAD65 and GAD67 by acute versus chronic stress suggest stimulus duration-dependent control of GAD biosynthesis. Chronic stress-induced increases in GAD65 mRNA expression predict enhanced availability of GAD65 apoenzyme after prolonged stimulation, whereas acute stress-specific GAD67 upregulation is consistent with de novo synthesis of active enzyme by discrete stressful stimuli.
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Azathioprine is used as an immunosuppressant in a variety of clinical situations, and its prolonged use is associated with an increased risk of solid malignancies. Three patients (one with rheumatoid arthritis and two with systemic lupus erythematosus) treated with azathioprine for 3 to 7 years developed acute myeloid leukemia (AML). The total cumulative doses of azathioprine varied from 89-260 g. An antecedent prolonged pancytopenic phase suggestive of myelodysplasia developed in all the cases. Morphological analysis showed AML with trilineage myelodysplastic features in residual marrow cells in all the cases. Karyotypic analysis showed deletion of the long arm of chromosome 7 (7q-) in one case and monosomy 7 (-7) in two cases. These were chromosomal aberrations typically associated with mutagen- or therapy-related AML. Fluorescence in situ hybridization with a chromosome-7-specific DNA probe was used to investigate the distribution of the monosomy 7 clone in two cases. Monosomy 7 was demonstrated in both the leukemic blasts and the residual myeloid cells of various stages of differentiation. This finding indicated that the leukemia had evolved from a mutated clone that was capable of terminal differentiation, which was consistent with the biological characteristics of the myelodysplastic syndromes. These cases represented therapy-related AML, as evidenced by clincopathological features, karyotypic aberrations of 7q-/-7, and demonstration of leukemic evolution from an underlying clonal myeloid disorder. The data support the hypothesis that azathioprine might be directly mutagenic.