Prior experience with behavioral control over stress facilitates social dominance.

Dominance status has extensive effects on physical and mental health, and an individual's relative position can be shaped by experiential factors. A variety of considerations suggest that the experience of behavioral control over stressors should produce winning in dominance tests and that winning should blunt the impact of later stressors, as does prior control. To investigate the interplay between competitive success and stressor control, we first examined the impact of stressor controllability on subsequent performance in a warm spot competition test modified for rats. Prior experience of controllable, but not physically identical uncontrollable, stress increased later effortful behavior and occupation of the warm spot. Controllable stress subjects consistently ranked higher than did uncontrollable stress subjects. Pharmacological inactivation of the prelimbic (PL) cortex during behavioral control prevented later facilitation of dominance. Next, we explored whether repeated winning experiences produced later resistance against the typical sequelae of uncontrollable stress. To establish dominance status, triads of rats were given five sessions of warm spot competition. The development of stable dominance was prevented by reversible inactivation of the PL or NMDA receptor blockade in the dorsomedial striatum. Stable winning blunted the later stress-induced increase in dorsal raphe nucleus serotonergic activity, as well as prevented uncontrollable stress-induced social avoidance. In contrast, endocrine and neuroimmune responses to uncontrollable stress were unaffected, indicating a selective impact of prior dominance. Together, these data demonstrate that instrumental control over stress promotes later dominance, but also reveal that winning experiences buffer against the neural and behavioral outcomes of future adversity.

Prior experience with behavioral control over stress facilitates social dominance.

Dominance status has extensive effects on physical and mental health, and an individual's relative position can be shaped by experiential factors. A variety of considerations suggest that the experience of behavioral control over stressors should produce winning in dominance tests and that winning should blunt the impact of later stressors, as does prior control. To investigate the interplay between competitive success and stressor control, we first examined the impact of stressor controllability on subsequent performance in a warm spot competition test modified for rats. Prior experience of controllable, but not physically identical uncontrollable, stress increased later effortful behavior and occupation of the warm spot. Controllable stress subjects consistently ranked higher than did uncontrollable stress subjects. Pharmacological inactivation of the prelimbic (PL) cortex during behavioral control prevented later facilitation of dominance. Next, we explored whether repeated winning experiences produced later resistance against the typical sequelae of uncontrollable stress. To establish dominance status, triads of rats were given five sessions of warm spot competition. Reversible inactivation of the PL or NMDA receptor blockade in the dorsomedial striatum led to a long-term reduction in social rank. Stable dominance blunted the later stress-induced increase in dorsal raphe nucleus serotonergic activity, as well as prevented stress-induced social avoidance. In contrast, endocrine and neuroimmune responses to uncontrollable stress were unaffected, indicating a selective impact of prior dominance. Together, these data demonstrate that instrumental control over stress promotes later dominance, but also reveal that winning experiences buffer against the neural and behavioral outcomes of future adversity.

SELECTED OPHTHALMIC PARAMETERS AND POTENTIAL RISK FOR LIGHT-INDUCED CATARACTS IN TWO COLONIES OF CAPTIVE INDIAN FLYING FOXES ( PTEROPUS GIGANTEUS).

Indian flying foxes ( Pteropus giganteus) are adapted to visual foraging in dim light. Nine Indian flying foxes were taken from a captive colony of 25 animals and placed in quarantine, off exhibit, in preparation for shipment to another institution. The exhibit had indirect, natural sunlight and was large enough to allow for flight. The quarantine enclosure was subject to >12 hr/day artificial lighting and did not allow for flight or gliding. Diet was identical between groups. After 13 mo, ophthalmic examination was performed on each animal including evaluation of the anterior chamber, rebound tonometry in upright and hanging positions, measurement of palpebral fissure length, and vertical and horizontal corneal diameters. Bilateral cataracts were observed in 55% (5/9) of the quarantined animals but in none of the animals that remained on exhibit (0/16). Bats housed in the quarantine enclosure had a risk of having cataracts 18 times greater than did bats in the exhibit enclosure (relative risk [RR]: 18.70; 95% confidence interval [CI]: 1.15-303.77). There was no association between cataract presence and age (odds ratio [OR]: 0.99; 95% CI: 0.97-1.02; P = 0.7) or sex (OR: 1.24; 95% CI: 0.17-9.25), but lower body weight was associated with presence of cataracts (OR: 0.98; 95% CI: 0.96-0.99). Other ophthalmic parameters observed were similar to those previously reported for other captive Megachiroptera. This study suggests that chronic exposure to artificial lighting predisposes fruit bats to developing light-induced cataracts.