Reproduction in aging normal and neonatally androgenized female rats.

Gerall, Arnold A.; Dunlap, Janis L.; Sonntag, William E.

doi:10.1037/h0077690

Cited by 18 publications

(8 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In agreement with previous reports (Davis et al 1977;Gerall et al 1980), we found that the intromittent requirements for pregnancy were greater for aged compared with those for young rats. For those old/cyclic animals which received a low number of intromissions, reproductive failure was associated with an absence of nocturnal prolactin surges (such surges were detected in only one out of four animals at day 3).…”

Section: Discussionsupporting

confidence: 94%

“…In PVO, ovulation does not occur spontaneously despite the presence of well-developed follicles (Meites et al 1978). In contrast to the young female, rats of 9-10 months of age exposed to only one ejaculation during mating do not readily become pregnant and exhibit plasma concentrations of progesterone similar to those of unmated controls (Davis, Gray & Dewsbury, 1977;Gerall, Dunlap & Sonntag, 1980). However, reasonably high pregnancy rates and plasma levels of progesterone after mating are observed for those aged females mated until three or five ejaculations have occurred.…”

Section: Introductionmentioning

confidence: 56%

See 1 more Smart Citation

Plasma Prolactin and Progesterone Responses to Mating Are Altered in Aged Rats

Hendricks¹,

Blake²

1981

Journal of Endocrinology

View full text Add to dashboard Cite

The effects of varying amounts of copulatory stimulation on patterns of plasma concentrations of prolactin and progesterone were evaluated in 3- and 12-month-old female rats. The 12-month-old group included rats which still exhibited oestrous cycles and rats in persistent vaginal oestrus (PVO). The extent of copulatory stimulation was defined by the number of intromissions received during mating: less than or equal to 5, 15 or greater than 50. Blood samples were drawn over the 8 days after mating through a cannula inserted into the right external jugular vein. Plasma from the samples was assayed for prolactin and progesterone. In aged but still cyclic rats, pregnancy rates were positively correlated with the number of intromissions received during mating. Only one rat in PVO became pregnant. All animals which became pregnant and rats in PVO which, after mating, exhibited a disruption of the pattern of PVO, showed the nocturnal surge of plasma prolactin characteristic of pregnant and pseudopregnant rats. While these surges persisted until day 8 after mating in pregnant animals, they were absent by this time in the rats in PVO. Prolactin surges were present in some but not all of the aged rats which did not become pregnant. Progesterone concentrations were raised in all pregnant animals except the one pregnant rat in PVO and, while not related to the number of intromissions, concentrations were higher 8 days after mating in young compared with those in aged pregnant rats. Plasma progesterone was low in rats in PVO regardless of disruption of the pattern of PVO. We have concluded that the failure of limited copulatory stimulation to induce pregnancy in older rats results, at least in part, from its failure to initiate nocturnal prolactin surges. Nevertheless, our data suggest that matings which are not experimentally limited should provide ample stimulation to establish such surges. Although reduced plasma concentrations of prolactin and progesterone at pro-oestrus and reduced plasma progesterone through part of gestation may contribute to decreasing fertility in aged rats, other unidentified factors appear to be involved in mediating the capacity of extensive copulatory stimulation to induce pregnancy in these animals.

show abstract

Section: Discussionsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 56%

Plasma Prolactin and Progesterone Responses to Mating Are Altered in Aged Rats

Hendricks¹,

Blake²

1981

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…In social species, such as sheep, higher rank usually results in females gaining access to better or more food, and thereby allows the production of larger, healthier and perhaps more offspring, as has been documented in other ruminant species [39,40] and primates [41]. However, there may be an overall trade-off, in that prenatal exposure resulting in mild masculinization may cause an early decrease in fertility, as evidenced by studies in the androgenized female rat [42].…”

Section: Chronic Estradiol Exposure Effects On Reproductionmentioning

confidence: 92%

Long-Term Exposure of Female Sheep to Physiologic Concentrations of Estradiol: Effects on the Onset and Maintenance of Reproductive Function, Pregnancy, and Social Development in Female Offspring1

Malcolm

Jackson

Bergeon

et al. 2006

Biology of Reproduction

View full text Add to dashboard Cite

As steroids and steroid-like compounds accumulate in the environment, it has become important to understand how low-dose exposure affects reproductive function. Ovary-intact sheep were used in a multigenerational study, to determine whether chronic exposure to low levels of estrogen disrupts reproductive function and behavior. We assessed parameters of reproductive performance in control and postnatally estradiol-treated females (Generation 1, G1), and their offspring (Generation 2, G2). In the G1 animals, 17beta-estradiol (E) was administered continuously from 4 wk of age at two doses via subcutaneous implants (ultralow E [<1 pg/ml in circulation, n = 8] or low E [1-3 pg/ml, n = 8]). Both doses delayed puberty; low E also produced pronounced prepubertal and seasonal anestrus hypogonadotropism, and delayed the onset of the second breeding season. All G1 animals conceived and produced offspring (G2), the treatment of which resulted from continuous maternal exposure during pregnancy and lactation. Behavioral observations of G2 females revealed that low prenatal E modestly masculinized play behavior and increased the frequency of attempts to displace competitors relative to ultralow E and control animals. The timing and magnitude of the LH surge also differed in prepubertal low prenatal E females relative to the controls, although these differences were not evident when retested at one year of age. These findings support the hypothesis that chronic exposure to physiologic amounts of exogenous estrogens has multigenerational effects on behavior and neuroendocrine function. Despite these disruptive steroid actions, ovarian cyclicity and fertility are not invariably compromised, pointing to an impressive resiliency of the reproductive axis to insult by exogenous estrogenic compounds.

show abstract

“…Both the SDN and AVPV are thought to play a role in the display of male sex behaviors (Rhees et al, 1999; Roselli et al, 2004), and lesion studies have demonstrated the critical importance of the AVPV in generating the preovulatory gonadatropin surge in females (Gerall et al, 1980; Wiegand and Terasawa, 1982). Although still highly controversial, in humans and sheep, a smaller SDN volume has been linked to the defeminization of sexual behavior and mate choice in males (Roselli et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Sex specific impact of perinatal bisphenol A (BPA) exposure over a range of orally administered doses on rat hypothalamic sexual differentiation

et al. 2013

View full text Add to dashboard Cite

Bisphenol A (BPA) is a high volume production chemical used in polycarbonate plastics, epoxy resins, thermal paper receipts, and other household products. The neural effects of early life BPA exposure, particularly to low doses administered orally, remain unclear. Thus, to better characterize the dose range over which BPA alters sex specific neuroanatomy, we examined the impact of perinatal BPA exposure on two sexually dimorphic regions in the anterior hypothalamus, the sexually dimorphic nucleus of the preoptic area (SDN-POA) and the anterioventral periventricular (AVPV) nucleus. Both are sexually differentiated by estradiol and play a role in sex specific reproductive physiology and behavior. Long Evans rats were prenatally exposed to 10, 100, 1000, 10,000 mg/kg bw/day BPA through daily, noninvasive oral administration of dosed-cookies to the dams. Offspring were reared to adulthood. Their brains were collected and immunolabeled for tyrosine hydroxylase (TH) in the AVPV and calbindin (CALB) in the SDN-POA. We observed decreased TH-ir cell numbers in the female AVPV across all exposure groups, an effect indicative of masculinization. In males, AVPV TH-ir cell numbers were significantly reduced in only the BPA 10 and BPA 10,000 groups. SDN-POA endpoints were unaltered in females but in males SDN-POA volume was significantly lower in all BPA exposure groups. CALB-ir was significantly lower in all but the BPA 1000 group. These effects are consistent with demasculinization. Collectively these data demonstrate that early life oral exposure to BPA at levels well below the current No Observed Adverse Effect Level (NOAEL) of 50 mg/kg/day can alter sex specific hypothalamic morphology in the rat.

show abstract

Reproduction in aging normal and neonatally androgenized female rats.

Cited by 18 publications

References 16 publications

Plasma Prolactin and Progesterone Responses to Mating Are Altered in Aged Rats

Plasma Prolactin and Progesterone Responses to Mating Are Altered in Aged Rats

Long-Term Exposure of Female Sheep to Physiologic Concentrations of Estradiol: Effects on the Onset and Maintenance of Reproductive Function, Pregnancy, and Social Development in Female Offspring1

Sex specific impact of perinatal bisphenol A (BPA) exposure over a range of orally administered doses on rat hypothalamic sexual differentiation

Contact Info

Product

Resources

About