Cloacal gland growth differences in high and low plasma corticosterone stress response line male quail reared under short daylengths

Mail quail selected (generation 32) for reduced [low stress (LS)] or exaggerated [high stress (HS)] plasma corticosterone stress response to brief mechanical restraint (5 min of immobilization) were studied for differences in the growth of their cloacal glands when reared essentially lifelong on short day lengths of 8L:16D. Post-brooding, at 4 wk of age, 96 quail (48 LS + 48 HS) were housed in cages (1 LS and 1 HS male/cage), and the short day light treatment was instigated. Using a digital caliper, cloacal gland (CG) size measurements (length and width, mm) were made biweekly beginning at 42 d of age and ending at 196 d of age (28 wk old). The CG volume (CVOL) was calculated from these measurements using a literature-proposed formula. The CVOL in both lines increased similarly with increasing age from 6 to 12 wk of age. However, beginning at 14 wk of age and thereafter, LS males showed greater (P < 0.05) CVOL than HS ones. No further increases in CVOL were observed in either line at 24 wk of age beyond that seen at 22 wk. This study demonstrated that although both lines show CG development under short days, eventually CG growth becomes comparatively stymied in the HS males. Furthermore, the maintenance of similarly lower CVOL in HS than LS males, CVOL that showed no further increase from 22 to 24 wk of age, suggests that holding these quail lifelong on short days results in, comparatively, yet another permanent negative reproductive consequence in quail selected for exaggerated plasma corticosterone stress responsiveness.Fil: Satterlee, Daniel G.. State University of Louisiana; Estados UnidosFil: Tong, M.. State University of Louisiana; Estados UnidosFil: Castille, S. A.. State University of Louisiana; Estados UnidosFil: Marin, Raul Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Ciencias y Tecnología de los Alimentos; Argentin

Plasma-corticosterone radioimmunoassay and levels in the neonate chick

The objective was to develop and validate a rapid, precise plasma corticosterone radioimmunoassay using a commercially available antiserum, for use in Gallus domesticus. Sample preparation consisted of sequential 2,2,4-trimethylpentane and dichloromethane extraction to partition progestins and glucocorticoids, respectively. Progesterone, 11 beta-Hydroxyprogesterone, and deoxycorticosterone significantly cross reacted with the antiserum used. However, progesterone was effectively removed prior to assay by the 2,2,4-trimethylpentane plasma washings while 11 beta-Hydroxyprogesterone and deoxycorticosterone interference is doubtful for reasons discussed. Standard curve data showed a linear range from 0 to 150 pg by log-logit transformation with a 5 pg assay sensitivity. Mean percent unlabeled corticosterone recovery was 96% with intraassay and interassay coefficients of variation being 3.75 and 5.62%, respectively. The assay was utilized to characterize corticosterone fluctuations during day one post hatch in broiler chicks. Method of blood collection, rapid decapitation vs. heart stab, resulted in no difference in mean plasma corticosterone levels. Corticosterone levels differed over a 24 hr sampling period, such that highest levels were found upon receipt of the chicks at the hatchery (approximately 20 ng/ml) and 20 hr later (approximately 11 ng/ml). Lowest plasma corticosterone concentrations occurred from 10 to 14 hr (approximately 6 ng/ml) after receipt of the chicks

Selection of Japanese quail for reduced adrenocortical responsiveness accelerates puberty in males

Differences in the onset of puberty were assessed in male Japanese quail from a random-bred (RB, control) line and two lines that had been genetically selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone response to brief mechanical restraint. At 42 d of age, cloacal gland area (CAREA) and volume (CVOL), proportion of individuals that produced cloacal gland foam (PICF), and intensity of cloacal gland foam production (CFP) were examined in 60 representatives from each of these quail lines. CFP was quantified by subjective scaling of the amount of foam ejected upon manual expression (squeezing) of the foam gland, using a scale of 1 (no foam expressed) to 5 (maximum amount of foam expression). Mean CAREA and CVOL were similar in quail of the RB and HS lines, but these measures were greater (P < 0.01) in the LS quail. In addition, more (P < 0.05) LS than HS birds expressed foam at 42 d, whereas RB quail exhibited an intermediate PICF response that was not different from either selected line. CFP results mimicked those found for PICF (i.e., LS quail produced a greater (P < 0.05) amount of foam than HS birds, whereas RB quail showed intermediate production that was not different from LS or HS levels). In prepubertal and pubertal Japanese quail, cloacal gland hypertrophy is androgen-dependent and highly positively correlated with testes size as well as sexual activity. Cloacal gland foam production is also considered a reliable indicator of testicular size and activity. Thus, we conclude that selection for reduced adrenocortical responsiveness in Coturnix is associated with acceleration in the onset of puberty in males. The potential interaction between adrenocortical and testicular activity as it relates to male reproductive performance is discussed.Fil: Satterlee, D.G.. State University of Louisiana; Estados UnidosFil: Marin, Raul Hector. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. State University of Louisiana; Estados UnidosFil: Jones, R. B.. Roslin Institute; Reino Unid

Stressor-induced changes in open-field behavior of Japanese quail selected for contrasting adrenocortical responsiveness to immobilization

The effect of no treatment (undisturbed controls; CON) or 5 min exposure to immobilization stress (STR) before assessment of open-field behavior in Japanese quail lines selected for high (high stress; HS) or low (low stress; LS) plasma corticosterone (B) response to a similar immobilization stress was examined. During a 5-min test period in an open field, the following behavioral measurements were made: the latency to ambulate (LAMB), the number of open-field floor sectors entered (SECTORS), and freezing behavior (total time spent in complete silence and inactivity, apart from slight movements associated with respiration; FREEZE). A further measure of ambulation across time (ambulation rate; ARATE) was calculated using the formula: ARATE = (SECTORS/[(300 s test ceiling) - LAMB)]. The LS-quail showed higher (P < 0.04) ARATE and lower (P < 0.05) FREEZE behavior than did their HS counterparts. When compared with the CON, quail exposed to STR showed decreased ARATE (P < 0.02) and numbers of open-field SECTORS entered (P < 0.04). More importantly, the LS-CON exhibited a higher (P < 0.05) mean ARATE, less FREEZE behavior, and increased numbers of SECTORS entered than did the other 3 treatment groups (LS-STR, HS-CON, and HS-STR), all of which showed similar responses for these variables. The LS-CON vs. HS-CON findings support our contention that selection for reduced adrenocortical responsiveness has been accompanied by a concomitant decrease in underlying fearfulness (exemplified herein by heightened activity in the open field in LS-CON). We further show here that this relationship was eliminated by application of an acute stressor before open-field testing of LS quail, wherein a reduction in activity similar to that found in both HS quail treatment groups was evident in comparison to the LS-CON.Fil: Satterlee, Daniel G.. State University of Louisiana; Estados UnidosFil: Marin, Raul Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Química. Cátedra de Química Biológica; Argentin

Sex differences in central benzodiazepine receptor densities and circulating corticosterone release after acute stress in broiler chicks

The purpose of the study was to determine the effect of sex on central benzodiazepine receptor (CBR) and serum corticosterone (CS) responses to an acute stressor in broiler chicks. Birds were housed in ten mixed-sex groups of eight chicks per cage. At 15 d of age, chicks were taken from a randomly selected cage and blood was immediately sampled (undisturbed controls), or they were taken from the same cage and immersed up to their necks in warm water (partial water immersion, PWI) for 15 min before blood was sampled. After blood sampling, forebrains were dissected for preparation of membranes, and bird sex was determined by gonadal inspection. Serum CS levels were determined by a competitive protein-binding assay. CBR densities were determined by radiolabeled receptor binding assay. There were no sex differences in serum CS levels or benzodiazepine receptor densities in controls. Exposure to PWI significantly increased (P < 0.01) circulating CS levels in both sexes, and this elevation was more pronounced (P < 0.01) in males than in females. Male, but not female, chicks also showed a significant stressor-induced increase (P < 0.01) in CBR densities. These findings showed sexual differences in acute, stressor-induced benzodiazepine and adrenocortical responses that suggest broiler males are more stress-susceptible than females.Fil: Marin, Raul Hector. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. State University of Louisiana; Estados UnidosFil: Benavidez, E.. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Garcia, D. A.. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Satterlee, D.G.. State University of Louisiana; Estados Unido