Inhibition of preovulatory gonadotropin secretion and stimulation of prolactin secretion by 7,12-dimethylbenz(a)anthracene in Sprague-Dawley rats.

摘要: Abstract Serum luteinizing hormone, follicle-stimulating prolactin, thyroid-stimulating and growth hormone hypothalamic luliberin thyroliberin contents were measured at given times of the estrous cycle in a dimethylbenz( )anthracene (DMBA)-susceptible strain rat (Sprague-Dawley) DMBA-resistant (Wistar) for periods up to appearance first mammary tumors DMBA-susceptible animals. Tumors usually appeared with ≃100% incidence around 14th 15th after DMBA treatment Sprague-Dawley rats. Hormonal determinations done by using groups 4-day cycling rats both strains which or vehicle (sesame oil) on single diestrus I 55 days life. Animals sacrificed decapitation without previous anesthesia morning afternoon proestrus estrus during 5th 11th cycles treatment. In female rats, significantly inhibited surges stimulated prolactin surge any (the timing preovulatory was same treatment); no difference found other cycle. contrast, Wistar did not show deranged basal gonadotropin release carcinogen; addition, time tested. These results that there is specific transient hormonal deregulation DMBA-susceptive Inasmuch as imbalance essentially throughout induction period, an early persistent alteration centers implicated cyclicity hypothalamopituitary axis must result from