Photoperiodic Regulation of Reproduction in Postpartum Peromyscus leucopus

Beasley, Laura J.; Johnston, Phyllis G.; Zucker, Irving H.

doi:10.1095/biolreprod24.5.962

Cited by 20 publications

(12 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is possible that the lack of difference in progesterone concentrations can be attributed to diestrus II-specific tissue collection, as progesterone concentrations are low at this point in the estrous cycle (Wynne-Edwards et al 1987, Reburn et al 1996. Diestrus II was selected since the vaginal cytology of acyclic photoperiod-sensitive rodents exposed to prolonged SD lengths is characteristic of diestrus II (Beasley et al 1981). Had tissues been collected on diestrus I, when progesterone reaches a maximum, differences in plasma progesterone concentrations may have been observed between basal SD and peak LD concentrations.…”

Section: Discussionmentioning

confidence: 99%

“…The following cellular characteristics were used to stage estrous cycles: estrus (many nonnucleated squamous cells, few endonucleated epithelial cells, no leukocytes), diestrus I (few nonnucleated squamous cells, many leukocytes), diestrus II (few endonucleated epithelial cells, many leukocytes) and proestrus (few nonnucleated epithelial cells, few leukocytes, many endonucleated epithelial cells). For a more accurate comparison among cycling individuals, tissues were collected from all hamsters only when their vaginal cytology revealed they were in diestrus II, as prolonged SD exposure induces vaginal 772 C S Moffatt-Blue and others cytology typical of this stage in photo-sensitive rodents (Beasley et al 1981). If it was determined that a hamster was not in diestrus II, vaginal smears were conducted on subsequent days until diestrus II was reached; the maximal number of additional days was fewer than 3 for all weeks of tissue collection.…”

Section: Animals and Tissue Processingmentioning

confidence: 99%

See 1 more Smart Citation

Short photoperiod-induced ovarian regression is mediated by apoptosis in Siberian hamsters (Phodopus sungorus)

Moffatt-Blue

Sury²,

Young³

2006

Reproduction

View full text Add to dashboard Cite

Siberian hamster reproduction is mediated by photoperiod-induced changes in gonadal activity. However, little is known about how photoperiod induces cellular changes in ovarian function. We hypothesized that exposing female hamsters to short (inhibitory) as opposed to long (control) photoperiods would induce an apoptosis-mediated disruption of ovarian function. Ovaries and plasma from hamsters exposed to either long (LD, 16 h light:8 h darkness) or short (SD, 8 h light:16 h darkness) days were collected during diestrus II after 3, 6, 9 and 12 weeks and processed for histology or RIA respectively. Apoptosis was assessed by in situ TUNEL and active caspase-3 protein immunolabeling. No significant differences were observed among LD hamsters for any parameter; therefore, these control data were pooled. SD exposure induced a decline in preantral follicles (P < 0.05), early antral/antral follicles (P < 0.01) and corpora lutea (P < 0.01) by week 12 as compared with LD. Terminal atretic follicles appeared by SD week 9; by week 12, these had become the predominant ovarian structures. Estradiol concentrations decreased by weeks 9 and 12 SD when compared with both LD and week-3 SD hamsters (P < 0.05); however, no changes were observed for progesterone. TUNEL-positive follicles in SD ovaries increased at week 3 and subsequently declined by week 12 as compared with LD ovaries (P < 0.01). Active capsase-3 protein immunostaining peaked at SD week 3 as compared with all other groups (P < 0.01). TUNEL and capsase-3 immunolabeling were localized to granulosa cells of late-preantral and early-antral/antral follicles. These data indicate that SD exposure rapidly induces follicular apoptosis in Siberian hamsters, which ultimately disrupts both estradiol secretion and folliculogenesis, resulting in the seasonal loss of ovarian function. IntroductionTo maximize survival when environmental resources are reduced, individuals of many temperate species limit reproductive function seasonally. In mammals, this adaptation is cued primarily by photoperiod-induced alterations in melatonin secretion from the pineal gland. For long-day (LD) seasonal breeders, such as Siberian hamsters (Phodopus sungorus), exposure to long photoperiods (. 12.5 h of light per day; short duration of melatonin release) induces and maintains reproductive function, whereas exposure to short photoperiods (, 12.5 h of light per day; long duration of melatonin release) results in the cessation of reproductive function (Hoffmann 1986, Bronson 1989, Knopper & Boily 2000, Prendergast & Nelson 2001. Extended periods of melatonin secretion negatively affect reproductive activity via inhibition of the hypothalamic-pituitary-gonadal (HPG) axis. In both males and females, short-day (SD) exposure reduces hypothalamic synthesis and secretion of gonadotropin-releasing hormone (GnRH) and, subsequently, the pituitary gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) (Glass 1986, Buchanan & Yellon 1991. Eventually, these endocrine alterations resu...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Animals and Tissue Processingmentioning

confidence: 99%

Short photoperiod-induced ovarian regression is mediated by apoptosis in Siberian hamsters (Phodopus sungorus)

Moffatt-Blue

Sury²,

Young³

2006

Reproduction

View full text Add to dashboard Cite

show abstract

“…Also, pairing with reproductively intact (as opposed to ovariectomized) females may be necessary to block reproductive regression in short days as it has been demonstrated in Siberian hamsters and juvenile P. maniculatus (14,35). This seems unlikely, however, because exposure to short days inhibits female P. leucopus reproductive status, behavior, and fecundity (1,34) and reduces reproductive tract mass and estradiol concentrations in P. maniculatus (deer mice; an ecologically similar related species; Refs. 9, 36), resulting in functional ovariectomy of females.…”

Section: Discussionmentioning

confidence: 99%

Social environment modulates photoperiodic immune and reproductive responses in adult male white-footed mice(Peromyscus leucopus)

Pyter¹,

Neigh²,

Nelson³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

Social cues may interact with photoperiod to regulate seasonal adaptations in photoperiod-responsive rodents. Specifically, photoperiod-induced adjustments (e.g., reproduction and immune function) may differ among individuals in heterosexual pairs, same-sex pairs, or isolation. Heterosexual cues may be more influential, based on their potential fitness value, than same-sex cues or no social cues. The present study examined the effects of pair (with a male or female) or individual housing on reproductive and immune responses in male white-footed mice ( Peromyscus leucopus) maintained in long or short photoperiods. Female pairing did not affect reproductive responses in short-day males. In long days, however, the presence of a female increased both testosterone concentrations and testes mass compared with individually housed and male-paired mice, respectively. Short-day, individually housed males enhanced delayed-type hypersensitivity (DTH) responses compared with single-housed mice in long days, but all paired groups decreased DTH responses regardless of photoperiod. The lack of enhanced DTH response in male mice paired with females coincided with reduced circulating corticosterone concentrations in both photoperiod treatments. Together, these results suggest that social environment may have important modulatory effects on photoperiod-regulated immune responses in male white-footed mice.

show abstract

“…It is likely that in voles, as in other rodents (Goldman & Darrow, 1983) (Johnston & Zucker, 1980;Beasley et al, 1981). It is more appropriate to consider indi¬ vidual traits as subject to photoperiodic regulation.…”

Section: Introductionmentioning

confidence: 99%

Daylength influences pelage and plasma prolactin concentrations but not reproduction in the prairie vole, Microtus ochrogaster

Smale¹,

Nelson²,

Zucker³

1988

Reproduction

View full text Add to dashboard Cite

Summary. Short daylengths did not affect testes weight or spermatogenic index in male voles or uterine weight in female voles. Short daylengths did stimulate the growth of a winter pelage in both sexes; short-day voles had longer underhairs and guard hairs and a thicker, more dense pelage than did long-day voles. Plasma prolactin concentrations were five times higher in long-day than in short-day females and 25% higher in l ong\ x=req-\ day males than in short-day males. The effect of short daylength on pelage was prevented by pinealectomy. We suggest that the growth of a winter coat is an obligate adaptation for winter survival, stimulated by exposure to short daylengths, but that changes in breeding activity are facultative and dependent to a greater extent on other cues for seasonal synchronization.

show abstract

Photoperiodic Regulation of Reproduction in Postpartum Peromyscus leucopus

Abstract: Many,if not most, successful matings in natural populations of rodents occur during postpartum estrus.

Cited by 20 publications

References 0 publications

Short photoperiod-induced ovarian regression is mediated by apoptosis in Siberian hamsters (Phodopus sungorus)

Short photoperiod-induced ovarian regression is mediated by apoptosis in Siberian hamsters (Phodopus sungorus)

Social environment modulates photoperiodic immune and reproductive responses in adult male white-footed mice(Peromyscus leucopus)

Daylength influences pelage and plasma prolactin concentrations but not reproduction in the prairie vole, Microtus ochrogaster

Contact Info

Product

Resources

About