Cloacal Gland Growth Differences in High and Low Plasma Corticosterone Stress Response Line Male Quail Reared Under Short Daylengths

Temporal dynamic of adrenocortical and gonadal photo-responsiveness in male Japanese quail exposed to short days

The study evaluated whether different short-term endocrine testicular and adrenocortical responses to short photoperiod exposure can persist over time and particularly when birds exhibit spontaneous cloacal gland recovery. At 11 wk of age, 33 male Japanese quail exposed to long photoperiod were switched to short photoperiod (8L:16D). Another group of males was kept under long photoperiod (n = 11; LD quail). After 5 wk of short photoperiod exposure, quail were classified as nonresponsive or responsive to short photoperiod, depending on whether the cloacal gland volume was above or below 1,000 mm(3) and with or without foam production, respectively. Since 11 wk of age and during a 20-wk period, droppings of all quail were collected to determine corticosterone and androgen metabolites (AM) by enzyme immunoassays. Cloacal gland volume was also determined weekly. Both short photoperiod nonresponsive (SD-NR) and responsive quail showed overall significantly lower (P < 0.01) AM values (518.8 ± 11.9 and 248.6 ± 17.1 ng/g, respectively) than quail that remained under long photoperiod (814.3 ± 24.1 ng/g). However, nonresponsive quail showed a significantly smaller reduction in their AM levels than their responsive counterparts. During the first 6 wk of short photoperiod exposure, SD-NR quail showed similar corticosterone metabolites values than LD quail. Corticosterone metabolite profiles changed from 7 wk of short photoperiod exposure onward, with photoperiodic differences (P < 0.01) persisting up to the end of study (LD: 228.9 ± 22.4 > SD-NR: 133.1 ± 15.5 > short photoperiod responsive: 61.6 ± 17.9 ng/g, respectively). Testicular and adrenocortical glands showed different degrees of activity associated with cloacal gland photoresponsiveness to short photoperiod manipulation. Our findings suggest long-term effects of short photoperiod, both in the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-adrenocortical axis activity of quail, including males that exhibited spontaneous cloacal gland recovery.

Cloacal gland, endocrine testicular, and adrenocortical photoresponsiveness in male Japanese quail exposed to short days

Photoperiod is the most important "noise-free" seasonal environmental cue for synchronizing physiological states (such as reproductive activity) in birds. However, in photoperiodic birds such as Japanese quail, the effect of photoperiod on adrenocortical activity remains unclear, particularly in males with differences in cloacal gland photoresponsiveness. At 8 wk of age, birds (n = 55) were either assigned to a short photoperiod (8L:16D; SD) or maintained under long photoperiod (16L:8D; LD; control). After 5 wk of SD exposure, males were classified as nonresponsive (SD-NR; with foam production) or responsive (SD-R; with no foam production) to short days, depending on the cloacal gland volume was above or below 1,000 mm(3). At 14 wk of age, droppings were collected during 3 consecutive days to determine corticosterone (CMs) and androgen metabolites (AMs) by enzyme immunoassays. Male Japanese quail under LD showed significantly higher concentrations of CMs (300 ± 10 ng/g) and AMs (1,257 ± 115 ng/g) than birds kept under SD. Under short days, SD-NR and SD-R showed differences (P < 0.0001), both in CM (153 ± 8 ng/g and 98 ± 6 ng/g, respectively) and AM concentrations (1,294 ± 309 ng/g and 275 ± 53 ng/g, respectively). Interestingly, although SD-NR males exhibited no cloacal gland arrest (according to cloacal gland volume and foam production) and similar testicular activity (AM values) to LD males, they showed lower concentrations of CMs compared with males that remained on LD (P < 0.05). Our findings suggest length of photoperiod affected hypothalamic-pituitary-adrenal activity; however, that was not the only factor involved, because birds subjected to shorter days but whose hypothalamic-pituitary-gonadal axis failed to respond had intermediate CM values. Further research is required to elucidate the underlying mechanisms of this interesting finding.

Short-term spatial memory responses in aged Japanese quail selected for divergent adrenocortical stress responsiveness

Stress-induced glucocorticoids can dampen learning and spatial memory via neuronal damage to the hippocampus. Cognition losses can be transient (associated with acute stress episodes) or permanent as in aged individuals who show chronic glucocorticoid-induced accelerated brain aging and neurodegeneration (dementia). Thus, chronic versus acute stress effects on spatial memory responses of quail selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone (B) response to brief restraint were assessed. Aged food-motivated male LS and HS quail were tested for 10 min in a feed-baited 8-arm radial arm maze (RAM) 1) at 255 d of age (quail who had experienced lifelong management stressors but who were otherwise never intentionally stressed; that is, chronically stressed birds), 2) on the next day post-acute stressor treatment (5 min of restraint), and 3) on the next day without treatment (acute stress recovery). The RAM tests used the win-shift procedure in which visited arms were not rebaited. Radial arm maze performance was measured by determination of the total number of arm choices made, the number of correct entries made into baited arms out of the first 8 choices, the time required to make a choice, and the number of pellets eaten. Line effects (P < 0.001 in all cases) were detected for total number of arm choices made (HS < LS), number of correct entries made into baited arms out of the first 8 choices (HS < LS), time required to make a choice (HS > LS), and number of pellets eaten (HS < LS). However, neither the effects of day of RAM testing nor its interaction with line further influenced these variables. Thus, although selection for divergent plasma B responsiveness to an acute stressor was found to be associated with severe impairment of spatial memory in aged male HS compared with LS quail, the observed spatial memory impairments (HS > LS) could not be further altered by acute stressor treatment. Line differences in cognition may reflect lifelong management-induced stress episodes that periodically produce higher plasma B responses in HS than LS quail, which underlie HS quail memory deficits, or other etiologies, or both.

Influence of maternal corticosterone treatment on incubation length of eggs laid by Japanese quail hens selected for divergent adrenocortical stress responsiveness

1. Previous studies have shown that more yolk corticosterone is found in the eggs of random bred Japanese quail hens implanted with corticosterone during egg formation; both unstressed and stressed quail hens selected for exaggerated (high stress) rather than reduced (low stress) plasma corticosterone response to brief restraint deposit more corticosterone into their egg yolks. The length of egg incubation is also known to be shorter in eggs laid by high than low stress hens. 2. Here we investigated the interactive effects of quail stress line (low vs. high stress) with maternal corticosterone treatment (empty implant controls vs. corticosterone-implants) during egg formation on length of egg incubation. 3. Mean (+/-SEM) length of egg incubation for high stress control eggs (3973 +/- 04 h) was similarly shorter (by about 4.5 h) than that found for low stress control eggs (3928 +/- 02 h). In addition, on average, the incubation length of eggs laid by corticosterone-implanted hens (3929 +/- 05 h) was nearly 3 h shorter than that found for eggs laid by control hens (3958 +/- 02 h) regardless of stress line. 4. Line x hen-implant treatment effects on mean (+/-SEM) length of egg incubation partitioned in rank order as follows: low stress control (3978 +/- 05 h) > low stress corticosterone-implant (3959 +/- 07 h) > high stress control (3938 +/- 03 h) > high stress corticosterone-implant (3912 +/- 04 h). 5. Our original contention that selection for exaggerated adrenocortical responsiveness is associated with a reduction in the length of egg incubation was supported. Because maternal stress-induced elevations of yolk B are known to occur, the present findings of further shortenings of the hatching times of eggs of corticosterone-treated hens of both stress lines are also important to the poultry industry because they warn producers that unless stress in hens during egg formation is minimised, abbreviated egg incubation periods may result beyond the effects that a hen's genetic predisposition to adrenocortical stress responsiveness has on the length of egg incubation.

The effects of testosterone on immune function in quail selected for divergent plasma corticosterone response

The immunocompetence handicap hypothesis (ICHH) suggests that the male sex hormone testosterone has a dual effect; it controls the development and expression of male sexually selected signals, and it suppresses the immune system. Therefore only high quality males are able to fully express secondary sexual traits because only they can tolerate the immunosuppressive qualities of testosterone. A modified version of the ICHH suggests that testosterone causes immunosuppression indirectly by increasing the stress hormone corticosterone (CORT). Lines of Japanese quail (Coturnix japonica)selected for divergent responses in levels of plasma CORT were used to test these hypotheses. Within each CORT response line (as well as in a control stock) we manipulated levels of testosterone in castrated quail by treatment with zero (sham), low or high testosterone implants, before testing the birds'humoral immunity and phytohaemagglutinin (PHA)-induced immune response, as well as body condition. The PHA-induced response was not significantly affected by CORT selected line, testosterone treatment or their interaction. There was, however, a significant effect of CORT line on humoral immunity in that the control birds exhibited the greatest antibody production, but there was no significant effect of testosterone manipulation on humoral immunity. The males in the sham implant treatment group had significantly greater mass than the males in the high testosterone group, suggesting a negative effect of high testosterone on general body condition. We discuss these results in the context of current hypotheses in the field of sexual selection.

Fear responses of offspring from divergent quail stress response line hens treated with corticosterone during egg formation

Increased fearfulness has been associated with adrenocortical activation. Maternal corticosterone (B) treatment increases egg B, and elevated B in ovo enhances chick avoidance of humans. Quail selected for exaggerated (high stress, HS) rather than reduced (low stress, LS) plasma B response to stress are more fearful, and more B is found in HS hen eggs. Thus, we used tonic immobility (TI) and hole-in-the-wall box (HWB) emergence tests to assess fear in chicks hatched from eggs of LS and HS hens implanted with B or no B (CON). The number of inductions required to attain TI, latency to first alert head movement, and duration of TI were determined in one study and the latency until first vocalization (LATVOC), numbers of vocalizations (VOCS), proportions of chicks vocalizing, and the latencies to head (HE) and full-body (FE) emergence from a HWB were assessed in another. The LS chicks required less inductions (P < 0.0005) and had shorter latency to first alert head movement (P < 0.02) than HS chicks, although the duration of TI was unaffected by any of the treatments. During the acclimation period of the HWB tests, more (proportions of chicks vocalizing; P < 0.0001) HS chicks alarm-called sooner (LATVOC; P < 0.0001) and more often (VOCS; P < 0.0001) than did LS chicks, and, although maternal implant treatment did not affect LATVOC, progeny of B-implanted hens showed a tendency toward less (P < 0.07) VOCS than the CON. Chicks hatched from eggs of B-implant mothers also took longer to achieve HE (P < 0.06) and FE (P < 0.05) from the HWB than did their CON counterparts. Stress line, implantation treatment, and their interaction did not alter HE or FE responses. The data suggest that quail stress line genome may or may not be affecting certain fear and alarm responses in chicks via the same mechanism(s) that underlies how elevating maternal B increases egg levels of B that in turn alters the fear behavior of progeny.

Ontogeny of the Cloacal Gland in Male Japanese Quail Classified in a T-Maze

Broiler chicks that traverse a T-maze quickly to reinstate contact with their companions (HP, high performers) are known to grow faster, are more social, and have a reduced plasma corticosterone response to acute stress than slower chicks (LP, low performers). High-performing quail from a line selected for reduced rather than exaggerated (high-stress) adrenocortical stress responsiveness also show enhanced female reproductive performance when compared with LP-high-stress quail. Herein, time courses of male sexual development were evaluated in genetically unremarkable quail that were categorized at 2 d of age as HP or LP in the T-maze. Body weight, cloacal gland volume (CVOL), proportion of individuals that produced cloacal gland foam, intensity of foam production, and CVOL relative to BW (RCVOL) were determined weekly from 4 to 10 wk of age, and again at 22 wk, along with absolute and BW-adjusted testes weight. Although CVOL and RCVOL were initially similar in both T-maze groups, both variables were greater (P < 0.05) in HP than in LP quail between 6 and 10 wk of age. High-performing birds also showed a trend (P < 0.1) of greater cloacal gland foam than their LP counterparts from 5 to 7 wk. From 8 wk on, all birds were in foam production. Intensity of foam production results generally mimicked those found for CVOL and RCVOL. Body weights were higher (P < 0.05) in HP than LP quail from 5 to 7 wk. No T-maze group differences were found in any of the variables at 22 wk of age. The results suggest that rapid negotiation of the T-maze is associated with accelerated growth and puberty in male quail, although the enhanced reproductive development of HP males does not remain extant in aged adults.