RESUMO
INTRODUCTION: The potential correspondence of precursor cells isolated from different brain regions is partially unknown. Since models and culture conditions used in several studies vary, comparison of precursor characteristics has been limited. OBJECTIVE: In this paper epidermal growth factor (EGF)-responsive precursors from the striatum and septum were isolated and their growth pattern in vitro were determined. We also evaluated the influence of fibroblast growth factor (FGF) and nerve growth factor (NGF) on the proliferation of these cells. MATERIAL AND METHODS: Dissociated cells from rat septum and striatum were cultivated in suspension with 20 ng/ml of EGF. Total cells quantification, immunocytochemical staining and neuron counts were used to evaluate cell proliferation and cellular phenotypes produced by EGF-generated cells. RESULTS: Considering both culture evolution and cellular growth we demonstrated a similar growth pattern of septal and striatal EGF-responsive precursors. Furthermore, the proliferation of both cells populations was supported by FGF. On the contrary, NGF neither had a proliferative effect nor affected cell survival. Upon differentiation, a small proportion of precursor cells differentiated into neuronal phenotype.
Assuntos
Corpo Estriado/embriologia , Corpo Estriado/metabolismo , Fator de Crescimento Epidérmico/metabolismo , Septo Pelúcido/embriologia , Septo Pelúcido/metabolismo , Animais , Diferenciação Celular/fisiologia , Movimento Celular/fisiologia , Sobrevivência Celular/fisiologia , Feminino , Fatores de Crescimento de Fibroblastos/metabolismo , Imuno-Histoquímica , Fator de Crescimento Neural/metabolismo , Neurônios/citologia , Gravidez , Ratos , Ratos WistarRESUMO
The relationship between GABA dynamics and LH release was studied on day 2 after subcutaneous estrogen implant in short-term ovariectomized rats. GABA accumulation, used as an index of GABA turnover, was determined in the medial preoptic nucleus (MPN), medial (MS) and lateral (LS) septal nuclei, median eminence-mediobasal hypothalamus (MBH) and locus ceruleus (LC). Measurements of GABA were performed at two different times of day (11.00 and 15.00 h), 3 h after intraperitoneal administration of gamma-vinyl-GABA (GVG), an irreversible inhibitor of GABA transaminase. Either morning or afternoon ovariectomized rats (OVX) showed a significant increase in GABA accumulation after GVG treatment in all the areas studied. Estrogen-treated OVX rats showed in the morning a lower GABA accumulation in the MPN, MBH and LC, and GABA levels remained unchanged in the LS and MS. In the afternoon, the MPN and LS showed a lower rate of GABA accumulation whereas in the MBH and LC the GABA increase was not observed. In contrast the MS showed a rate of GABA accumulation similar as in the OVX rats. Local administration in the MPN of 20 micrograms GVG, or GABA-A receptor stimulation by muscimol (50 ng), prior to the increase in plasma LH levels, prevented the occurrence of the estradiol-induced LH surge. The effect of muscimol was reversed by bicuculline (30 ng), a GABA-A receptor antagonist. Bicuculline in low doses lacked effect by itself. In conclusion, these results strongly suggest that a decreased GABAergic activity in MPN, MBH and LC precedes the estradiol-evoked LH surges in ovariectomized rats. Moreover, that in septal nuclei, a low GABAergic activity takes place well before the occurrence of plasma LH increase.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Encéfalo/metabolismo , Estradiol/farmacologia , Hormônio Luteinizante/metabolismo , Área Pré-Óptica/metabolismo , Taxa Secretória/efeitos dos fármacos , Ácido gama-Aminobutírico/fisiologia , Animais , Feminino , Hipotálamo Médio/metabolismo , Locus Cerúleo/metabolismo , Ovário/fisiologia , Radioimunoensaio , Ratos , Ratos Endogâmicos , Receptores de GABA-A/efeitos dos fármacos , Septo Pelúcido/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
We have studied the binding of the synthetic antimineralocorticoid [3H]ZK 91587 to soluble receptors in brain of adrenalectomized rats. It was observed that [3H]ZK 91587 labeled a single receptor class with high affinity (Kd 1.3 nM) and low capacity (51.1 fmol/mg prot.) in cytosol of hippocampus (HIPPO). The ligand was efficiently displaced in vitro from the receptor by aldosterone (IC50 2.0 nM) and corticosterone (2.3), while dexamethasone showed less potency (IC50 5.1 nM) and the pure antiglucocorticoid RU 28362 competed weakly (161 nM). Furthermore, there was a widespread distribution of binding sites all over the brain for this compound, but with CA1 and CA3 regions of HIPPO, some amygdaloid nuclei and lateral septum containing most of the binding sites, as revealed by binding assays employing 16 different microdissected brain regions. Finally, the receptor labeled with [3H]ZK 91587 was readily displaced by administration of aldosterone in vivo in physiological amounts, from 5 whole brain regions examined, but preferentially from preoptic area, amygdala and HIPPO. It is concluded that [3H]ZK 91587 is a useful ligand for further studies on putative mineralocorticoid responsive cells in brain, due to its high affinity, stability and lack of cross reactivity with glucocorticoid receptors. Its brain distribution is similar to that previously obtained using [3H]aldosterone in the presence of RU 28362 to block ligand binding to the glucocorticoid receptor.
Assuntos
Encéfalo/metabolismo , Mineralocorticoides/antagonistas & inibidores , Receptores de Esteroides/metabolismo , Espironolactona/análogos & derivados , Adrenalectomia , Aldosterona/metabolismo , Tonsila do Cerebelo/metabolismo , Animais , Ligação Competitiva , Corticosterona/metabolismo , Hipocampo/metabolismo , Masculino , Antagonistas de Receptores de Mineralocorticoides , Ratos , Ratos Endogâmicos , Receptores de Mineralocorticoides , Receptores de Esteroides/antagonistas & inibidores , Septo Pelúcido/metabolismo , Espironolactona/metabolismo , Distribuição TecidualRESUMO
Stereoselective competition was used to determine (3H)-aldosterone binding to type I corticosteroid receptors, and (3H)-dexamethasone binding to type II receptors in punches obtained from 11 brain regions of short-term adrenalectomized (ADX) rats. It was observed that type I receptor binding was almost exclusive of the hippocampus (HIPPO), while type II receptor binding was more generally distributed among HIPPO, cerebral cortex, lateral septum, ventromedial and arcuate hypothalamic nuclei, with lower levels in 6 additional regions studies. We determined corticosterone (CORT) in brain punches from ADX rats, ADX rats receiving CORT for 5 days, intact rats and intact rats receiving ACTH for 5 days. We correlated (3H)-ligand binding with CORT content in punches obtained from identical brain regions and showed a significant positive correlation in the case of the ADX plus CORT group, for type II corticosteroid receptors. Similarly, a significant correlation emerged with type II sites, when binding capacity was correlated with percentage increases of CORT in brain areas of rats receiving ACTH. It is suggested that in situations where CORT levels are elevated, changes in CORT retention throughout the brain occur as a function of the type II glucocorticoid receptor, although at the level of the HIPPO, both receptors may provide appropriate control of the CNS-pituitary-adrenal axis, according to the physiological or stress levels of circulating hormone.