The Development of Gonadotropin and Steroid Hormone Patterns in Male and Female Hamsters from Birth to Puberty*

Abstract

Male (1--60 days old) and female (1--30 days old) hamsters were decapitated and serum levels of LH, FSH, PRL, progesterone, androgens (males), and estradiol (females) were measured by RIA. Males and females had similar levels of LH until 15 days of age and of FSH until 12 days of age, at which times gonadotropin levels increased significantly in females. Peak levels for females occurred on days 19--21 for LH and on days -2--24 for FSH, later than the times reported for female rats. Adjusting female gonadotropin peaks for gestation length places these peaks for hamsters and rats at the same time in postmating age. In female hamsters, large variations occur in LH between 16--25 days of age, as reported for female rats. Males reached peak serum levels of LH and FSH on day 40, just before the first motile epididymal sperm. Serum PRL levels were identical in male and female hamsters until at least day 30. PRL levels sharply increased in both sexes after day 18 and remained elevated until at least day 30. In males, serum androgens were low until 30 days of age, in contrast to high levels reported for infantile rats. Androgens rose sharply in male hamsters after day 30 to peak levels on day 50. Progesterone in males also remained low until after day 30. Serum estradiol in females did not attain the extremely high elevations seen in rats. Some fluctuations occurred between 10--30 days of age, which presumably represent maturational changes in the ovary. Serum progesterone in females followed a pattern of development similar to estradiol.

Follicular assembly: mechanisms of action

“…FSH is present in the serum of neonatal mice and hamsters (Vomachka & Greenwald 1979, Halpin et al 1986) and the FSH receptor is detected using RT-PCR in neonatal mouse ovaries (O'Shaughnessy et al 1994). Inactivation of FSH using an anti-FSH antibody results in the inhibition of primordial follicle formation in the hamster (Roy & Albee 2000), while addition of FSH to cultured ovaries results in acceleration of primordial follicle formation (Wang & Roy 2004).…”

Photoperiodic modulation of testicular LH receptors in the bank vole (Clethrionomys glareolus)

“…Experimentally induced supraphysiological prolactin levels have been observed to induce testicular atrophy in rats (Bartke et al, 1982). Earlier studies with bank voles and other rodent species indicate that inhibitory photoperiods induce a decline in the plasma concentrations of LH, FSH and prolactin whereas a sequential increase is observed during normal testicular maturation (Clarke, 1977;Vomachka & Greenwald, 1979;Craven & Clarke, 1982;Yellon & Goldman, 1984). This normal sequential pattern of trophic hormone secretion is disrupted when young are subjected from birth to an inhibitory photoperiod.…”

Differential responsiveness to fluoxetine during puberty.

“…In males, this time period is marked by an increase in testosterone levels, testicular development, and the emergence of sexual behaviors (Goldman & Swanson, 1975;Miller, Whitsett, Vandenbergh, & Colby, 1977;Vomachka & Greenwald, 1979;Wommack, Salinas, Melloni, & Delville, 2004). On the basis of these variables, puberty can be divided into three categories: early, mid, and late.…”