Expression of CYP2A3 mRNA and its regulation by 3-methylcholanthrene, pyrazole, and ß-ionone in rat tissues

Cytochrome P450 (CYP) 2A enzymes are involved in the metabolism of numerous drugs and hormones and activate different carcinogens. Human CYP2A6, mouse CYP2A5 and rat CYP2A3 are orthologous enzymes that present high similarity in their amino acid sequence and share substrate specificities. However, different from the human and mouse enzyme, CYP2A3 is not expressed in the rat liver. There are limited data about expression of CYP2A3 in extrahepatic tissues and its regulation by typical CYP inducers. Therefore, the objective of the present study was to analyze CYP2A3 mRNA expression in different rat tissues by RT-PCR, and to study the influence of 3-methylcholanthrene, pyrazole and ß-ionone treatment on its expression. Male Wistar rats were divided into four groups of 5 rats each, and were treated ip for 4 days with 3-methylcholanthrene (25 mg/kg body weight), pyrazole (150 mg/kg body weight), ß-ionone (1 g/kg body weight), or vehicle. Total RNA was extracted from tissues and CYP2A3 mRNA levels were analyzed by semiquantitative RT-PCR. CYP2A3 mRNA was constitutively expressed in the esophagus, lung and nasal epithelium, but not along the intestine, liver, or kidney. CYP2A3 mRNA levels were increased in the esophagus by treatment with 3-methylcholanthrene and pyrazole (17- and 7-fold, respectively), in lung by pyrazole and ß-ionone (3- and 4-fold, respectively, although not statistically significant), in the distal part of the intestine and kidney by 3-methylcholanthrene and pyrazole, and in the proximal part of the intestine by pyrazole. CYP2A3 mRNA was not induced in nasal epithelium, liver or in the middle part of the intestine. These data show that, in the rat, CYP2A3 is constitutively expressed in several extrahepatic tissues and its regulation occurs through a complex mechanism that is essentially tissue specific

Caracterizaçäo do leite de cabras mestiças no Brejo Paraibano, durante o período de lactaçäo / Caracterization of goat milk in Paraíba during days of lactation

Objetiva determinar alguns caracteres físicos e químicos do leite de cabra das raças Anglo Nubiana, Parda Alpina e Saanen, mestiçadas com animais SRD (Sem Raça Definida), no Brejo Paraibano. O experimento foi conduzido durante 195 dias de lactaçäo, realizando-se coletas nos turnos da manhä e da tarde, com intervalo de 15 dias entre as coletas. Dentre as raças estudadas, foram observadas as seguintes variaçöes médias: proteína 3,09 a 3,25 g/100g; lipídios 4,6 a 5,5 g/ 100ml; lactose 4,11 a 4,26 g/100ml; extrato seco total 12,75 a 13,90 g/100g e cinzas 0,682 a 0,744 g/100g. As concentraçöes de lipídios e extrato seco total foram influenciadas significativamente (P<0,05) pelo turno de ordenha e grupo genético, enquanto que os teores médios de cinzas variaram em funçäo do grupo genético. As concentraçöes médias de lactose e proteína mantiveram-se estáveis durante o período estudado, em funçäo dos parâmetros analisados.