RESUMO
The objective of this study was to evaluate the effects of a single intramammary infusion of Panax ginseng extract (GS) on insulin-like growth factors (IGF) in bovine mammary gland during early involution. Eight mammary quarters from six nonpregnant cows in late lactation were infused with 10 mL of ginseng extract solution (3 mg/mL), six quarters were treated with 10 mL of placebo (vehicle alone) and six quarters were maintained as uninoculated controls. Milking was interrupted after infusion. Concentrations of IGF1 in mammary secretions were higher in GS-treated quarters than in placebo and uninoculated control quarters at 24, 48 and 72 h post-treatment (p<0.05). Treatment with GS did not affect mammary secretion of IGF2 (p=0.942). At 7 d of post-lactational involution, a decrease of immunostained area and mRNA expression for IGF1 was observed in mammary tissue of GS-treated quarters compared with placebo-treated quarters and uninoculated controls (p<0.05). The IGF2 immunostained area and mRNA expression for this growth factor were not affected by GS treatment (p=0.216 and p=0.785, respectively). An increase in protein levels and mRNA expression in mammary tissue of IGFBP3, IGFBP4 and IGFBP5 was observed in GS-treated quarters compared with placebo-treated quarters and uninoculated controls (p<0.05). These results provide evidence that intramammary inoculation of GS extract at cessation of milking may promote early mammary involution through the inhibition of IGF1 local production and bioavailability.
Assuntos
Glândulas Mamárias Animais/efeitos dos fármacos , Panax , Extratos Vegetais/farmacologia , Somatomedinas/efeitos dos fármacos , Animais , Bovinos , Feminino , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/análise , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , Proteína 3 de Ligação a Fator de Crescimento Semelhante à Insulina/efeitos dos fármacos , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/análise , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/efeitos dos fármacos , Proteína 5 de Ligação a Fator de Crescimento Semelhante à Insulina/análise , Proteína 5 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , Proteína 5 de Ligação a Fator de Crescimento Semelhante à Insulina/efeitos dos fármacos , Fator de Crescimento Insulin-Like I/análise , Fator de Crescimento Insulin-Like I/biossíntese , Fator de Crescimento Insulin-Like I/efeitos dos fármacos , Fator de Crescimento Insulin-Like II/análise , Fator de Crescimento Insulin-Like II/biossíntese , Fator de Crescimento Insulin-Like II/efeitos dos fármacos , Lactação/efeitos dos fármacos , Glândulas Mamárias Animais/química , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Somatomedinas/análise , Somatomedinas/biossínteseRESUMO
Estrogen receptors (ERs) are nuclear transcription factors that regulate gene expression in response to estrogen and estrogen-like compounds. Identification of estrogen-regulated genes in target cells is an essential step toward understanding the molecular mechanisms of estrogen action. Using cDNA microarray examinations, 19 genes were identified as induced by 17 beta-estradiol in MCF-7 cells, 10 of which have been reported previously to be estrogen responsive or to be linked with ER status. Five known estrogen-regulated genes, E2IG4, IGFBP4, SLC2A1, XBP1 and B4GALT1, and AFG3L1, responded quickly to estrogen treatment. A novel estrogen-responsive gene was identified and named EEIG1for early estrogen-induced gene 1. EEIG1 was clearly induced by 17 beta-estradiol within 2 h of treatment, and was widely responsive to a group of estrogenic compounds including natural and synthetic estrogens and estrogenic environmental compounds. EEIG1 was expressed in ER-positive but not in ER-negative breast cancer cell lines. EEIG1 expression was repressed by antiestrogens 4-OH-tamoxifen and ICI 182,780 but not by protein synthesis inhibitors cycloheximide and puromycin. These results provide evidence that some estrogenic compounds differentially enhance the transcription of estrogen-regulated genes and suggest a role for EEIG1 in estrogen action.