scholarly journals Timing of Maternal Immunization Affects Immunological and Behavioral Outcomes of Adult Offspring in Siberian Hamsters (Phodopus sungorus )

2016 ◽  
Vol 325 (6) ◽  
pp. 377-389 ◽  
Author(s):  
Susannah S. French ◽  
Emily M. Chester ◽  
Gregory E. Demas
Keyword(s):  
Behavioral Outcomes ◽  
Phodopus Sungorus ◽  
Adult Offspring ◽  
Maternal Immunization ◽  
Siberian Hamsters

Energy intake and fur in summer- and winter-acclimated Siberian hamsters (Phodopus sungorus)

2001 ◽  
Vol 281 (2) ◽  
pp. R519-R527 ◽  
Author(s):  
Alexander S. Kauffman ◽  
Alessandra Cabrera ◽  
Irving Zucker
Keyword(s):  
Food Intake ◽  
Energy Intake ◽  
Ventral Surface ◽  
Phodopus Sungorus ◽  
Ambient Temperatures ◽  
Siberian Hamsters ◽  
Daily Food ◽  
Brown Adipose ◽  
Wide Range ◽  
The Impact

Few studies have directly addressed the impact of fur on seasonal changes in energy intake. The daily food intake of Siberian hamsters ( Phodopus sungorus) was measured under simulated summer and winter conditions in intact animals and those with varying amounts of pelage removed. Energy intake increased up to 44% above baseline control values for approximately 2–3 wk after complete shaving. Increases in food intake varied with condition and were greater in hamsters housed in short than long day lengths and at low (5°C) than moderate (23°C) ambient temperatures. Removal of 8 cm2 of dorsal fur, equivalent to 30% of the total dorsal fur surface, increased food intake, but removal of 4 cm2 had no effect. An 8-cm2 fur extirpation from the ventral surface did not increase food consumption. Food intake was not influenced differentially by fur removal from above brown adipose tissue hot spots. Fur plays a greater role in energy balance in winter- than summer-acclimated hamsters and conserves energy under a wide range of environmental conditions.

scholarly journals Peripubertal Immune Challenges Attenuate Reproductive Development in Male Siberian Hamsters (Phodopus sungorus)1

2004 ◽  
Vol 70 (3) ◽  
pp. 813-820 ◽  
Author(s):  
Brian J. Prendergast ◽  
Andrew K. Hotchkiss ◽  
Staci D. Bilbo ◽  
Randy J. Nelson
Keyword(s):  
Reproductive Development ◽  
Phodopus Sungorus ◽  
Siberian Hamsters ◽  
Immune Challenges

scholarly journals Photoperiod and Testosterone Interact to Drive Seasonal Changes in Kisspeptin Expression in Siberian Hamsters (Phodopus sungorus )

2008 ◽  
Vol 20 (12) ◽  
pp. 1339-1347 ◽  
Author(s):  
T. J. Greives ◽  
S. A. Humber ◽  
A. N. Goldstein ◽  
M.-A. L. Scotti ◽  
G. E. Demas ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Phodopus Sungorus ◽  
Siberian Hamsters

NPY Y1 receptor antagonist prevents NPY-induced torporlike hypothermia in cold-acclimated Siberian hamsters

2008 ◽  
Vol 294 (1) ◽  
pp. R236-R245 ◽  
Author(s):  
John Dark ◽  
Kimberly M. Pelz
Keyword(s):  
Body Temperature ◽  
Receptor Antagonist ◽  
Receptor Agonist ◽  
Phodopus Sungorus ◽  
Food Ingestion ◽  
Research Groups ◽  
Ambient Temperatures ◽  
Y1 Receptor ◽  
Siberian Hamsters ◽  
Intracerebroventricular Injections

Siberian hamsters ( Phodopus sungorus) undergo bouts of daily torpor during which body temperature decreases by as much as 20°C and provides a significant savings in energy expenditure. Natural torpor in this species is normally triggered by winterlike photoperiods and low ambient temperatures. Intracerebroventricular injection of neuropeptide Y (NPY) reliably induces torporlike hypothermia that resembles natural torpor. NPY-induced torporlike hypothermia is also produced by intracerebroventricular injections of an NPY Y1 receptor agonist but not by injections of an NPY Y5 receptor agonist. In this research, groups of cold-acclimated Siberian hamsters were either coinjected with a Y1 receptor antagonist (1229U91) and NPY or were coinjected with a Y5 receptor antagonist ( CGP71683 ) and NPY in counterbalanced designs. Paired vehicle + NPY induced torporlike hypothermia in 92% of the hamsters, whereas coinjection of Y1 antagonist + NPY induced torporlike hypothermia in 4% of the hamsters. In contrast, paired injections of vehicle + NPY and Y5 antagonist + NPY induced torporlike hypothermia in 100% and 91% of the hamsters, respectively. Although Y5 antagonist treatment alone had no effect on body temperature, Y1 antagonist injections produced hyperthermia compared with controls. Both Y1 antagonist and Y5 antagonist injections significantly reduced food ingestion 24 h after treatment. We conclude that activation of NPY 1 receptors is both sufficient and necessary for NPY-induced torporlike hypothermia.

Perinatal photoperiod organizes adult immune responses in Siberian hamsters (Phodopus sungorus)

2006 ◽  
Vol 290 (6) ◽  
pp. R1714-R1719 ◽  
Author(s):  
Zachary M. Weil ◽  
Leah M. Pyter ◽  
Lynn B. Martin ◽  
Randy J. Nelson
Keyword(s):  
Immune System ◽  
Immune Function ◽  
Breeding Season ◽  
Somatic Growth ◽  
Developmental Trajectory ◽  
Day Length ◽  
Phodopus Sungorus ◽  
Siberian Hamsters ◽  
Time Of Year ◽  
Induced Changes

Individuals of many nontropical rodent species display reproductive, immunological, and somatic responses to day length. In general, short day (SD) lengths inhibit reproduction and enhance immune function in the laboratory when all other conditions are held constant. Most studies to date have focused on seasonal variation in immune function in adulthood. However, perinatal photoperiods also communicate critical day length information and serve to establish a developmental trajectory appropriate for the time of year. Nontropical rodents born early in the breeding season undergo rapid reproductive development, presumably to promote mating success during their first reproductive season. Rodents born late in the breeding season suspend somatic growth and puberty until the following vernal breeding season. We tested the hypothesis that perinatal day lengths have similar enduring effects on the immune system of rodents. Siberian hamsters ( Phodopus sungorus) were maintained prenatally and until weaning (21 days) in either SDs (8 h light:16 h dark) or long days (LD) (16 h light:8 h dark), then they were weaned into either the opposite photoperiod or maintained in their natal photoperiod, forming four groups (LD-LD, LD-SD, SD-LD, and SD-SD). After 8-wk in these conditions, cell-mediated immune activity was compared among groups. SD-SD hamsters of both sexes enhanced immune function relative to all other groups. The reproductive effects of perinatal photoperiod were not evident by the end of the experiment; circulating testosterone and cortisol sampled at the end of the experiment reflected the postweaning, but not the perinatal photoperiod. This experiment demonstrates long-lasting organizational effects of perinatal photoperiod on the rodent immune system and indicates that photoperiod-induced changes in the immune system are dissociable from changes in the reproductive system.

Cardiac dynamics during daily torpor in the Djungarian hamster (Phodopus sungorus)

2008 ◽  
Vol 294 (2) ◽  
pp. R639-R650 ◽  
Author(s):  
Alexander Mertens ◽  
Oliver Stiedl ◽  
Stephan Steinlechner ◽  
Michael Meyer
Keyword(s):  
Conduction Block ◽  
Phodopus Sungorus ◽  
Control Mechanisms ◽  
Daily Torpor ◽  
Qrs Complex ◽  
Siberian Hamsters ◽  
Cardiac Dynamics ◽  
St Segment ◽  
Electrocardiogram Ecg ◽  
Ventricular Conduction

Djungarian or Siberian hamsters ( Phodopus sungorus) acclimated to short photoperiod display episodes of spontaneous daily torpor with metabolic rate depressed by ∼70% and body temperature (Tb) reduced by ∼20°C. To study the cardiovascular adjustment to daily torpor in Phodopus, electrocardiogram (ECG) and Tb were continuously recorded by telemetry during entrance into torpor, in deep torpor, and during arousal from torpor. Minimum Tb during torpor bouts was ∼21°C, and heart rate, ∼349 beats/min at euthermy, displayed marked sinus bradyarrhythmia at ∼70 beats/min. Arousal was typically completed within ∼40 min, followed by a sustained posttorpor inactivity tachycardia (∼540 beats/min). The absence of episodes of conduction block, tachyarrhythmia, or other forms of ectopy throughout the torpor cycle demonstrates a remarkable resistance to arrhythmogenesis. The ECG morphology lacks a distinct isoelectric interval following the QRS complex, and the ST segment resembles the ECG pattern in mice, with a prominent fast transient outward K+ current ( Ito,f) determining the early phase of ventricular repolarization. During low-temperature torpor, the amplitudes of the QRS complex substantially increased, suggesting that in the euthermic state the terminal portion of ventricular depolarization is fused with the beginning of repolarization, low Tb acting to decorrelate the superposition between depolarization and repolarization by delaying the repolarization onset. Atrioventricular and ventricular conduction times were prolonged as function of Tb. In contrast, the QT vs. Tb relationship showed marked hysteresis indicating the operation of nonlinear control mechanisms whereby the rapid QT shortening during arousal results from additional mechanisms (probably sympathetic stimulation) other than temperature alone.

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