A new hypoprolactinemic rat strain. Prolactin, luteinizing hormone, follicle-stimulating hormone, testosterone and corticosterone levels in males and effects of two anesthetics

Abstract

A new strain of rat, the IPL nude rat, derived by spontaneous mutation from the Sprague-Dawley strain, is characterized by a lack of hair, delayed puberty and a total lack of lactation. To characterize partially the endocrine system in this rat, serum levels of prolactin (Prl), luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone and corticosterone were quantified. The content of gonadotropins and Prl in the pituitary gland was also measured. Blood samples were collected following decapitation or by cardiac puncture after ether or ketamine anesthesia. Serum levels of Prl were decreased by approximately 50% in IPL nude compared to normal Sprague-Dawley rats, regardless of the method used for collection of the samples. There were also significantly reduced levels of testosterone, LH and FSH in the serum collected from IPL nude rats. Levels of corticosterone in serum were similar in IPL nude and normal rats. There was the same relative response to anesthesia in the levels of all the hormones measured when the data from IPL nude and normal rats were compared. The quantities of LH, FSH and Prl contained in the pituitary of the IPL nude rats were not significantly different from those observed in normal rats. These data suggest that the serum hormone deficiencies observed in the nude IPL rat may be due to an altered regulation of hormone production by hypothalamic factors.