RESUMO
Three transgenic females from a first generation transgenic male were induced to lactate between 11 and 12 months of age using a series of estrogen and progesterone injections. The milk contained human longer acting tissue plasminogen activator (LAtPA) at comparable concentrations (1-3 mg/ml) as occurred in the original founder female. In addition, the transgenic male was induced with a hormonal regime and was shown to produce 0.85 mg/ml of LAtPA. Milk protein gels indicated that the milk products (casein, IgG) were essentially normal. These experiments show that expression data for this vector can be evaluated in a shorter period of time in dairy goats than would be required through normal gestation and lactation schedules and can be used to identify the relative expression of transgenes in mammary tissue that would occur during normal lactation.
Assuntos
Animais Geneticamente Modificados , Caseínas/genética , Expressão Gênica , Cabras , Lactação/genética , Glândulas Mamárias Animais/metabolismo , Ativador de Plasminogênio Tecidual/genética , Animais , DNA Complementar/genética , Estradiol/farmacologia , Feminino , Humanos , Masculino , Progesterona/farmacologia , Proteínas Recombinantes de FusãoRESUMO
Mating stimuli received by female rats activate a neuroendocrine mnemonic system which produces daily diurnal and nocturnal prolactin (PRL) surges for the first half of gestation, surges which help maintain corpora lutea function and a viable pregnancy. Since these PRL surges may be regulated in part by endogenous opioids and opioid sensitivity declines as a function of multiple births, we decided to investigate the possibility that prior parity might affect the post-coital diurnal and nocturnal PRL surges, reducing their magnitude and/or occurrence. Age-matched, nulliparous and primiparous rats were mated to males from our colony. On days 5 or 10 of pregnancy females received jugular catheters. Blood samples were collected at regular intervals from 1000 h on day 7 to 1000 h on day 8, and from 1000 h on day 12 to 1000 h on day 13 of gestation in separate sets of multigravid and primigravid rats. Measurement of plasma PRL by radioimmunoassay revealed that prior reproductive experience altered the patterns and levels of plasma PRL. Plasma PRL levels were significantly reduced during both the diurnal and nocturnal surges on days 7-8 in multigravid rats when compared with levels in primigravid rats. No differences in PRL levels were found between primigravid and multigravid groups on days 12 to 13 of gestation. The changes in diurnal and nocturnal PRL surges during early pregnancy indicate that prior parity reduces the subsequent secretion of PRL, possibly by altering the neuroendocrine regulation of this hormone.
