Polyploidization of rat liver following sex hormone administration to castrate and intact rats

Abstract

This study was initiated to clarify and extend our previously reported investigation of the effect of castration on development of polyploid nuclei in the rat liver (Swartz, Sams and Barton, '60). It was then observed that lack of sex hormone was associated with a 50% or greater loss of octaploid nuclei in both sexes while diploid and tetraploid percentages remained unaltered. This relative decrease of octaploid ( 8 N ) population appeared to be superimposed upon the more generalized and widely recognized growth response of the two sexes to hormonal deprivation, in which males show a decreased, and females an increased, growth rate. The observations suggested that the liver, in addition to adherence to general bodily growth pattern, exhibits a specific response to estrogen and testosterone manifested by cytological shifts in particular cell populations. In this sense the liver appeared to exhibit a growth pattern similar to that of the sex accessories under hormonal stimulation.The apparent dependency of the 8N class of liver nuclei on sex hormones led us to initiate the following three experiments: {a) study of polyploidization following sex hormone administration to castrate weanling rats; (b) study of effect on polyploidization of sex hormone administration to intact newborn rats; (c) polyploidization following sex steroid administration to hypophysectomized castrate weanling rats. The results of the first two studies will be reported and discussed here, and the third, not yet complete, will be the subject of a separate paper. For the sake of clarity the two investigations will be reported individually, the first under the heading "(a) sex hormone-castrate'' and the second under the heading "(b) sex hormone-intact ." MATERIAL AND METHODSSex hormone-castrate. Animals comprising this study represent all surviving males and females from 3 litters of Sprague-Dawley rats castrated at time of weaning. Hadf the castrate females were given 0.08 mg of estrone (Parke, Davis and Co. Theelin, aqueous suspension) subcutaneously three times per week and half the castrate males 0.5 mg testosterone (Schering Oreton, aqueous suspension) daily (except Sunday) until 80 days of age, after which they received 1.0 mg injections on the same schedule. Littermate controls were given an equal number of 0.9% saline injections of equal volume. The animals were maintained on and ad libitum diet of Purina Laboratory Chow and weighed weekly. 4t 130 -t-3 days of age all were killed by stunning and decapitation. Liver cubes, approximately 2 mm, were fixed overnight in Lavdowsky's fluid and cut at 10 LI following routine ethyl alcohol-paraffin processing. Liver weight, tail length and humerus length were obtained. Percentages of polyploid nuclei were determined both by microdensitometry and visual classification on Feulgen-stained sections, as previously described (Swartz and Ford, '60). P values and standard errors were derived from the t test for small samples as described by Bancroft ('57).Sex hormone-intact. These animals represent the sur...

Hepatic nuclear ploidy distribution of dietary-restricted mice.

“…Whether this effect is a result of hormones is not known. However, estrogens have been reported to affect the distribution of octaploid nuclei during the estrous cycle in mice (37), with major changes seen in the octaploid nuclei (38). DR is known to decrease estrous cycling and associated hormones in mice (18,20).…”

The Effect of Neonatal Administration of Sex Hormones on Ribonucleic Acid Metabolism in the Liver of Male and Female Rats

“…From the findings in the experiments on rats gonadectomized at 4 weeks of age, the levels of sex hormones at the actual time of measurement of the incorporation of 3 2p into liver nuclear RNA seem to be relatively unimportant. It seems probable that the sex-linked difference in nuclear RNA metabolism is to be correlated with the high DNA content (Li et al, 1965) and the large number of big, polyploid nuclei (Swartz and Sams, 1961;Toh, 1971b) in the liver of male rats as compared with females and, like the difference in RNA metabolism, the occurrence of polyploidy is due rather to the neonatal hormonal pattern than to the genetic sex differences or the hormonal background in adult life (Toh, 1971b).…”