scholarly journals Photoperiod-dependent regulation of inhibin in Siberian hamsters: II. Regulation of inhibin production and secretion by pregnant mare serum gonadotropin

2002 ◽  
Vol 174 (1) ◽  
pp. 85-94 ◽  
Author(s):  
HA Kenny ◽  
DJ Bernard ◽  
TH Horton ◽  
TK Woodruff
Keyword(s):  
Follicle Stimulating Hormone ◽  
Phodopus Sungorus ◽  
Seasonal Differences ◽  
Siberian Hamsters ◽  
Pregnant Mare Serum Gonadotropin ◽  
Gonadotropin Stimulation ◽  
Serum Gonadotropin ◽  
Follicle Maturation ◽  
Ovarian Inhibin ◽  
Short Days

Inhibin production differs in ovaries of Siberian hamsters (Phodopus sungorus) exposed to long days (LD) or short days (SD). We believe that seasonal differences in serum follicle-stimulating hormone contribute to this difference. However, given the profound photoperiodic differences in follicle maturation, serum gonadotropins alone may not account for all of the observed differences in inhibin processing. To test this hypothesis, we challenged LD and SD female hamsters with exogenous gonadotropins. While both groups responded with increased inhibin expression, the effects were muted in ovaries of SD females and there was no evidence of ovulation in these animals. These data indicate that the ovaries of SD females are not immediately equipped to respond to gonadotropin stimulation. More generally, these data suggest that photoperiodic history affects ovarian inhibin production and secretion in response to gonadotropins.

Follicle stimulating hormone versus pregnant mare serum gonadotropin for superovulation of dairy goats

1992 ◽  
Vol 8 (3) ◽  
pp. 217-224 ◽  
Author(s):  
R.J. Pendleton ◽  
C.R. Youngs ◽  
R.W. Rorie ◽  
S.H. Pool ◽  
M.A. Memon ◽  
...  
Keyword(s):  
Follicle Stimulating Hormone ◽  
Dairy Goats ◽  
Pregnant Mare Serum Gonadotropin ◽  
Serum Gonadotropin ◽  
Stimulating Hormone

scholarly journals A proposed sequence of hormones controlling the induction of luteal 20α-hydroxy steroid dehydrogenase and progesterone withdrawal in the late-pregnant rat

1976 ◽  
Vol 160 (3) ◽  
pp. 663-670 ◽  
Author(s):  
D H Smith ◽  
N J Kuhn
Keyword(s):  
Follicle Stimulating Hormone ◽  
Late Pregnancy ◽  
Pregnant Rats ◽  
Pregnant Rat ◽  
Human Choriogonadotropin ◽  
Pregnant Mare Serum Gonadotropin ◽  
Progesterone Synthesis ◽  
Serum Gonadotropin ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

1. The previously reported induction of luteal 20α-hydroxy steroid dehydrogenase by administration of aminoglutethimide to late-pregnant rats was shown to be unaffected by prior removal of the foetuses. Aminoglutethimide therefore does not act via the foetuses in this context. 2. The ability of injected oestrogen to prevent the above induction was lost by delaying the injection for 12h after aminoglutethimide, although the increase in enzyme activity begins only after 24h. 3. Induction of 20α-hydroxy steroid dehydrogenase by foetoplacental removal on day 18 of pregnancy was inhibited by human choriogonadotropin, lutropin (luteinizing hormone) and pregnant-mare serum gonadotropin, but not by somatotropin (growth hormone), thyrotropin or follitropin (follicle-stimulating hormone) 4. Indomethacin blocked the normal induction of 20α-hydroxy steroid dehydrogenase in late pregnancy and that caused by aminoglutethimide. It partially blocked that caused by human choriogonadotropin given on days 19-20 and that caused by 2-bromo-α-ergocryptine on days 5-6, but failed to block that caused by human choriogonadotropin on days 15-16 or by foetoplacental removal on day 18 of pregnancy. 5. These findings, and the control of progesterone synthesis in late pregnancy, are interpreted in terms of a sequence of hormonal or enzymic syntheses, each of which is inhibited by the product of the preceding synthesis.

Photoperiod differentially affects energetics of immunity in pregnant and lactating Siberian hamsters (Phodopus sungorus)

2003 ◽  
Vol 81 (8) ◽  
pp. 1406-1413 ◽  
Author(s):  
Deborah L Drazen ◽  
Anjali Trasy ◽  
Randy J Nelson
Keyword(s):  
Humoral Immunity ◽  
Antibody Production ◽  
Keyhole Limpet Hemocyanin ◽  
Phodopus Sungorus ◽  
Siberian Hamsters ◽  
Long Day ◽  
Pregnancy And Lactation ◽  
Body Production ◽  
Reproductive Processes ◽  
Short Days

Both immune and reproductive (i.e., pregnancy and lactation) functions are energetically demanding processes that fluctuate seasonally. Winter is energetically demanding because energy availability is limited and energy demands are high. The goal of the present study was to assess the trade-off of resources between immunity and reproduction by examining antibody production during pregnancy and lactation, when energy requirements are high. Female Siberian hamsters (Phodopus sungorus) were held in either long or short days, and anti-keyhole limpet hemocyanin antibody production was assessed in pregnant, lactating, or nulliparous animals. Pregnancy and lactation both suppressed humoral immunity (primary antibody production) in long-day Siberian hamsters. However, although antibody production was reduced in short-day females compared with long-day animals, pregnancy and lactation did not reduce antibody body production any further. Interestingly, the size and mass of the litters produced by females in both long and short days did not differ. Taken together, these results suggest that the processes of pregnancy and lactation are costly enough to reduce humoral immunity, and they suggest that immunity may be compromised as a result of energy allocation to these reproductive processes.

Butyric acid suppresses palatable food consumption in Siberian hamsters (Phodopus sungorus) housed in short, but not long, photoperiods

2009 ◽  
Vol 87 (9) ◽  
pp. 749-754
Author(s):  
Joanna L. Workman ◽  
Eric M. Johnson ◽  
Lynn B. Martin ◽  
Randy J. Nelson
Keyword(s):  
Food Consumption ◽  
Butyric Acid ◽  
Food Restriction ◽  
Skim Milk ◽  
Phodopus Sungorus ◽  
Milk Consumption ◽  
Palatable Food ◽  
Short Day ◽  
Siberian Hamsters ◽  
Short Days

Short days induce winter-like adaptations in small mammals such as Siberian hamsters ( Phodopus sungorus (Pallas, 1773)). Specifically, hamsters adjust food consumption, metabolic processes, and immune function to optimize energetic needs and promote winter survival. One potentially inexpensive behavioral adaptation to increase survival is avoidance of infection. We tested the hypothesis that photoperiod affects avoidance of potentially infected food. In experiment 1, hamsters were weaned into either short or long days with ad libitum food. Three weeks later, hamsters were presented with either skim milk treated with butyric acid (2%), a bacterial product that serves as a potent cue of spoilage, or unadulterated skim milk; consumption was measured. After milk presentation, blood samples were obtained to assess cortisol. In experiment 2, skim-milk consumption was again assessed after 3 weeks in either short or long days. In experiment 3, we tested the hypothesis that food avoidance was due to photoperiod-induced differential neophobia. Short-day hamsters increased milk consumption, which was blocked by butyric acid. Short days increased cortisol concentrations; neither food restriction nor butyric acid affected cortisol concentrations. Photoperiod did not alter neophobic responses. These experiments suggest that short-day hamsters avoid food treated with butyric acid possibly as an adaptive trait to avoid costly winter infections.

Rapid photoperiod-induced increase in detectable GnRH mRNA-containing cells in Siberian hamster

1997 ◽  
Vol 273 (6) ◽  
pp. R2032-R2039 ◽  
Author(s):  
Tarja Porkka-Heiskanen ◽  
Naherin Khoshaba ◽  
Kathryn Scarbrough ◽  
Janice H. Urban ◽  
Martha H. Vitaterna ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Follicle Stimulating Hormone ◽  
Hormone Secretion ◽  
Gonadotropin Releasing Hormone ◽  
Early Step ◽  
Siberian Hamsters ◽  
Long Day ◽  
Long Photoperiod ◽  
Short Days

To determine whether changes in gonadotropin-releasing hormone (GnRH) neurons are early indicators of photostimulation, Siberian hamsters were placed in short days (6:18-h light-dark) at 3 ( experiment 1) or 6 ( experiment 2) wk of age where they were held for 3 ( experiment 1) or 4 ( experiment 2) wk. Hamsters were then moved to long photoperiod (16:8-h light-dark). In experiment 1, brains were collected 1–21 days after transfer from short to long days. In experiment 2, brains were collected only on the second morning of long day exposure. Long and short day controls were included in both experiments. Cells containing GnRH mRNA, as visualized by in situ hybridization, were counted. As expected, there were no differences in the number of detectable GnRH mRNA-containing cells among animals chronically exposed to long or short photoperiods. However, on the second morning after transfer from short to long photoperiod, a positive shift in the distribution of GnRH mRNA-containing cells occurred relative to the respective controls in the two experiments. Increases in follicle-stimulating hormone secretion and gonadal growth occurred days later. In conclusion, a rapid but transient increase in the distribution of detectable GnRH mRNA-containing cells is an early step in the photostimulation of the hypothalamic-pituitary-gonadal axis.

scholarly journals Superovulation of Cows Using a Follicle Stimulating Hormone or Pregnant Mare Serum Gonadotropin

1992 ◽  
Vol 45 (7) ◽  
pp. 471-475 ◽  
Author(s):  
NORIYUKI OHISA ◽  
NAOKAZU TAKADA ◽  
TAKASHI NUMABE ◽  
ITARU YOSHIURA ◽  
YUSHI ISHIKAWA
Keyword(s):  
Follicle Stimulating Hormone ◽  
Pregnant Mare Serum Gonadotropin ◽  
Serum Gonadotropin ◽  
Stimulating Hormone
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