Pinning in the Play Fighting of Rats: A Comparative Perspective With Methodological Recommendations

During play fighting, rats attack and defend the nape and during the course of this competitive interaction, they may adopt a configuration in which one animal stands over its supine partner (i.e., pin). Because the pin configuration is typically frequent and relatively easy to identify, it has been widely used as a marker to detect the effects of experimental treatments. In the present study, the frequency of pinning during standardized, 10min trials in three strains of rats, Long Evans hooded (LE), Sprague-Dawley (SD) and wild (WWCPS), was compared. LE and SD had higher rates than WWCPS rats (#/min: 6.5, 5.5, 1.5, respectively). When adjusted for strain differences in the frequency of attacks, SD as well as WWCPS rats had lower rates of pinning compared to LE rats. Both SD and WWCPS rats were less likely to use tactics of defense that promote pinning. Moreover, while the majority of the pins achieved in LE rats arose from the defender actively rolling over onto its back, the majority of pins in WWCPS rats arose because one partner pushed the other onto its back. SD rats were intermediate in this regard. Finally, once they do adopt the pin configuration, SD rats are less likely to remain supine than LE and WWCPS rats. That is, both SD and WWCPS rats have significantly fewer pins than LE rats, but a different combination of factors account for this. These data highlight the need to use a battery of measures for ascertaining the effects of experimental manipulations on play. Some suggested guidelines are provided.

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Domestication and the Role of Social Play on the Development of Sociocognitive Skills in Rats

International Journal of Comparative Psychology ◽

10.46867/ijcp.2019.32.00.17 ◽

2019 ◽

Vol 32 ◽

Author(s):

Sergio M. Pellis ◽

Vivien C. Pellis ◽

Brett T. Himmler ◽

Klaudia Modlinska ◽

Rafał Stryjek ◽

...

Keyword(s):

Cognitive Skills ◽

Strain Differences ◽

Juvenile Period ◽

Play Fighting ◽

Play Interactions ◽

Wild Rat ◽

Rearing Condition ◽

Wild Rats ◽

Long Evans

Several studies on rats and hamsters, across multiple laboratories, have shown that limiting play in the juvenile period leads to adults that have physiological and anatomical changes in the medial prefrontal cortex (mPFC) and reduced socio-cognitive skills. Peers raised with playful peers have better socio-cognitive skills than animals raised with adult partners. Using Long Evans hooded rats - a commonly used domesticated strain - this relationship has been replicated multiple times. However, when the same paradigm was used with laboratory-reared wild rats, no differences were found between rats reared with peers and ones reared with adults. It has been shown that the key play-generated experiences involved are those related to actively wrestling with a partner and turn taking (as measured by role reversals), which give both partners opportunity to gain the advantage during play fighting. In the present study, we tested the hypothesis that wild rat adults provide juveniles more such experiences than do adult Long Evans rats. The asymmetry in the play interactions in adult-juveniles pairs was compared between the two strains. As predicted, wild rat adults initiated more play with the juveniles, wrestled more and provided more opportunities for role reversals. The findings thus support the hypotheses for the observed strain differences in the effects of rearing condition on the mPFC.

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Ventilatory phenotypes among four strains of adult rats

Journal of Applied Physiology ◽

10.1152/japplphysiol.00019.2002 ◽

2002 ◽

Vol 93 (3) ◽

pp. 974-983 ◽

Cited By ~ 41

Author(s):

Matthew R. Hodges ◽

Hubert V. Forster ◽

Paula E. Papanek ◽

Melinda R. Dwinell ◽

Genevieve E. Hogan

Keyword(s):

Ventilatory Response ◽

Strain Difference ◽

Strain Differences ◽

Inbred Strains ◽

The Other ◽

Brown Norway ◽

Control Mechanisms ◽

Sprague Dawley ◽

Adult Rats ◽

Different Strains

Our purpose in this study was to identify different ventilatory phenotypes among four different strains of rats. We examined 114 rats from three in-house, inbred strains and one outbred strain: Brown Norway (BN; n = 26), Dahl salt-sensitive ( n = 24), Fawn-hooded Hypertensive (FHH: n = 27), and outbred Sprague-Dawley rats (SD; n = 37). We measured eupneic (room air) breathing and the ventilatory responses to hypoxia (12% O2-88% N2), hypercapnia (7% CO2), and two levels of submaximal exercise. Primary strain differences were between BN and the other strains. BN rats had a relatively attenuated ventilatory response to CO2 ( P < 0.001), an accentuated ventilatory response to exercise ( P < 0.05), and an accentuated ventilatory roll-off during hypoxia ( P < 0.05). Ventilation during hypoxia was lower than other strains, but hyperventilation during hypoxia was equal to the other strains ( P > 0.05), indicating that the metabolic rate during hypoxia decreased more in BN rats than in other strains. Another strain difference was in the frequency and timing components of augmented breaths, where FHH rats frequently differed from the other strains, and the BN rats had the longest expiratory time of the augmented breaths (probably secondary to the blunted CO2 sensitivity). These strain differences not only provide insight into physiological mechanisms but also indicate traits (such as CO2 sensitivity) that are genetically regulated. Finally, the data establish a foundation for physiological genomic studies aimed at elucidating the genetics of these ventilatory control mechanisms.

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Dexmedetomidine Ameliorate CLP-Induced Rat Intestinal Injury via Inhibition of Inflammation

Mediators of Inflammation ◽

10.1155/2015/918361 ◽

2015 ◽

Vol 2015 ◽

pp. 1-9 ◽

Cited By ~ 15

Author(s):

Yanqing Chen ◽

Liyan Miao ◽

Yusheng Yao ◽

Weilan Wu ◽

Xiaodan Wu ◽

...

Keyword(s):

Survival Rate ◽

Western Blot ◽

Sham Group ◽

Intestinal Injury ◽

The Other ◽

Protective Effects ◽

Sprague Dawley ◽

Sd Rats ◽

Additional Group ◽

Lactate Levels

The aim was to verify that dexmedetomidine (DEX) can attenuate CLP-induced intestinal injury via inhibition of inflammation. Male Sprague-Dawley (SD) rats were randomly allocated into Sham group and the other three CLP model groups, in terms of different treatments: placebo, DEX, and yohimbine plus DEX (DEX + YOH) groups. Pathology examination was conducted with HE stain. To identify differences among groups, the levels of DAO, and D-lactate in serum were measured by spectrophotometry, and the levels of TNF-α, IL-1β, and IL-6 in serum and organ were measured by ELISA. The expressions of occludin and TLR4 in tissue were detected by Western blot. The survival rate of an additional group of animals within 7 d was recorded. In DEX group, mortality was lower, histology change was minor, DAO, and D-lactate levels were reduced, and occludin expression was increased; the expressions of TNF-α, IL-1β, IL-6, and TLR4 were also decreased in DEX group. These results indicated that acute intestinal injury induced by CLP was mitigated by DEX treatment. However, these effects of DEX were significantly attenuated by yohimbine in DEX + YOH group. Our study indicated the protective effects of DEX on CLP-induced injury, which may be associated with the inhibition of inflammation via modulating TLR4 pathway and can be blocked by yohimbine.

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Effects of Δ9-tetrahydrocannabinol (THC) vapor inhalation in Sprague-Dawley and Wistar rats

10.1101/541003 ◽

2019 ◽

Cited By ~ 2

Author(s):

Michael A. Taffe ◽

K. M. Creehan ◽

Sophia A. Vandewater ◽

Tony M. Kerr ◽

Maury Cole

Keyword(s):

Propylene Glycol ◽

Plasma Levels ◽

Intraperitoneal Injection ◽

Wistar Rats ◽

Indirect Comparison ◽

Strain Differences ◽

Sprague Dawley ◽

Differential Impact ◽

Sd Rats ◽

Dose Dependent

AbstractA novel inhalation system based on e-cigarette technology has been recently shown to produce hypothermic and anti-nociceptive effects of Δ9-tetrahydrocannabinol (THC) in rats. Indirect comparison of some prior investigations suggested differential impact of inhaled THC between Wistar (WI) and Sprague-Dawley (SD) rats, thus this study was conducted to directly compare the strains.Groups (N=8 per strain) of age matched male SD and WI rats were prepared with radiotelemetry devices to measure temperature and then exposed to vapor from the propylene glycol (PG) vehicle or THC (25, 100, 200 mg/mL of PG) for 30 or 40 minutes. Additional studies evaluated plasma THC levels and anti-nociceptive effects after THC inhalation as well as the thermoregulatory effect of intraperitoneal injection of THC (5-30 mg/kg).Hypothermic effects of inhaled THC was more pronounced in SD rats however plasma levels of THC were identical across strains under either fixed inhalation conditions or injection of a mg/kg equivalent dose. Strain differences in hypothermia were even more pronounced after i.p. injection of THC with SD rats exhibiting dose-dependent temperature reduction after 5 or 10 mg/kg, i.p. and the WI rats only exhibiting significant hypothermia after 20 mg/kg, i.p. The anti-nociceptive effects of inhaled THC (100, 200 mg/mL) did not differ significantly across the strains. These studies confirm an insensitivity of WI rats, compared with SD rats, to the hypothermia induced by THC following inhalation conditions that produced identical plasma THC and anti-nociception. Thus strain differences were not due to differential THC delivery via vapor inhalation.

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Rat Strain and Sex Differences in Leptin Responses to Immobilization Stress

Journal of Individual Differences ◽

10.1027/1614-0001.27.3.136 ◽

2006 ◽

Vol 27 (3) ◽

pp. 136-146 ◽

Cited By ~ 3

Author(s):

Rachel M. Ceballos ◽

Martha M. Faraday ◽

Laura Cousino Klein

Keyword(s):

Immobilization Stress ◽

Strain Differences ◽

Baseline Period ◽

Interactive Effects ◽

Stress Exposure ◽

Sprague Dawley ◽

Sprague Dawley Rats ◽

Rat Strain ◽

Long Evans ◽

Plasma Leptin

The effects of immobilization (IM) stress on plasma leptin levels and bodyweight in adult Sprague-Dawley (19 males, 20 females) and Long-Evans (20 males, 20 females) rats were investigated. Following a 10-day baseline period, half the animals from each experimental group were exposed to immobilization stress or no-stress 20 min/day for 21 days. Plasma leptin and corticosterone levels were measured following stress or no-stress exposure on the last day of the experiment. Corticosterone levels confirmed stress exposure. Important interactive effects of stress, strain, and sex on leptin and corticosterone levels were also observed. Specifically, females displayed higher leptin levels than did males, regardless of stress exposure. Strain interacted with stress such that stressed Long-Evans rats displayed higher leptin levels than did stressed Sprague-Dawley rats; there were no strain differences in leptin levels among nonstressed rats. Also, correlations between leptin and corticosterone were strain-specific. Results are discussed with respect to previously unreported strain differences in the effects of immobilization stress on circulating plasma leptin and the relevance to inconsistent findings in the human literature.

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Long-Evans and Sprague-Dawley rats exhibit divergent responses to refeeding after caloric restriction

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00602.2004 ◽

2005 ◽

Vol 288 (6) ◽

pp. R1468-R1476 ◽

Cited By ~ 32

Author(s):

S. A. Evans ◽

M. M. Messina ◽

W. D. Knight ◽

A. D. Parsons ◽

J. M. Overton

Keyword(s):

Food Intake ◽

Caloric Restriction ◽

Sprague Dawley ◽

Sd Rats ◽

Sprague Dawley Rats ◽

Complete Restoration ◽

Ad Libitum ◽

Long Evans ◽

Strain Dependent ◽

Stimulation Of

Mature male Sprague-Dawley (SD) and Long-Evans (LE) rats were instrumented with telemetry transmitters for measurement of heart rate (HR) and housed in room calorimeters for assessment of food intake and oxygen consumption (V̇o2) at standard laboratory temperatures (23°C) to examine physiological responses to caloric restriction (CR; 60% of baseline ad libitum calories for 2 wk) and refeeding. Ad libitum controls had stable food intake (84–88 kcal/day) and gained weight at rates of 3–4 g/day. Groups from both strains assigned to CR exhibited similar patterns of weight loss and reductions in V̇o2 and HR. Upon refeeding, SD rats exhibited a mild, transient hyperphagic response (1 day) accompanied by sustained suppression of V̇o2 and HR that remained evident 8 days after refeeding. In contrast, LE rats exhibited sustained daily hyperphagia that persisted 8 days after refeeding and was accompanied by a complete restoration of HR and V̇o2. The lower HR and V̇o2 observed during refeeding in SD rats were not due to reduced locomotor activity. The results reveal a strain-dependent divergent response to recovery from CR. We conclude that during recovery from CR, homeostatic stimulation of appetite or suppression of energy expenditure may occur selectively to restore body weight.

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Strain differences in response of Sprague-Dawley and Long Evans Hooded rats to the teratogen nitrofen

Teratology ◽

10.1002/tera.1420340211 ◽

1986 ◽

Vol 34 (2) ◽

pp. 213-223 ◽

Cited By ~ 25

Author(s):

Y. J. Kang ◽

L. Zolna ◽

J. M. Manson

Keyword(s):

Strain Differences ◽

Sprague Dawley ◽

Long Evans

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The Development of Strain Typical Defensive Patterns in the Play Fighting of Laboratory Rats

International Journal of Comparative Psychology ◽

10.46867/ijcp.2014.27.03.09 ◽

2014 ◽

Vol 27 (3) ◽

Author(s):

Stephanie M. Himmler ◽

Jena M. Lewis ◽

Sergio M. Pellis

Keyword(s):

Strain Difference ◽

Strain Differences ◽

Social Experiences ◽

Sprague Dawley ◽

Typical Pattern ◽

Juvenile Period ◽

Laboratory Rats ◽

Play Fighting ◽

Divergent Behavior ◽

Early Juvenile Period

During play fighting, rats attack and defend the nape, which if contacted is nuzzled with the snout. While all strains of rats can use all defensive tactics to protect the nape, there are strain-typical preferences for using particular tactics This study tests two hypotheses for this strain difference: (1) that each strain has strain-specific thresholds for each tactic, or (2) that each strain attacks differently which leads to strain differences in which defense tactics are used. Juvenile Long-Evans and Sprague-Dawley males were tested with both unfamiliar (experiment 1) and familiar (experiment 2) same-strain and different-strain partners. Experiment two was conducted to determine if familiarity with a different strain might allow rats to modify their strain-typical pattern of play. If hypothesis (1) were true, they would maintain strain-typical defense patterns irrespective of partner strain, whereas for (2) it would vary with partner strain. Hypothesis (1) was supported in the first experiment; all the rats maintained their strain-typical patterns regardless of the partner’s strain. However, the second experiment supported neither hypothesis, as each animal displayed strain-divergent behavior when playing with partners of a different strain as well as with partners of the same strain. Given that in the second experiment subjects were reared in mixed-strain groups, it is possible that, during the early juvenile period, animals are susceptible to discordant social experiences

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