Hepatitis B Virus (HBV)

Episodic Gonadotropin Secretion: RESULTS

RESULTS

Testis Size

Birds used in these experiments had similar body conformation as well as normal comb and male secondary sexual characteristics, and they weighed 4063 ± 160 g. In experiment 1, testis weights (n = 8) varied by as much as 4.4-fold, from an individual mean of 6.3 to 27.6 g (Table 1). In contrast, testis weight (n = 20) varied from 25.5 to 52.1 g in experiment 2.

Gonadotropin Secretion

Experiment 1. Average concentrations of LH and FSH in plasma varied among individual broilers (Table 1). However, concentrations of LH (8.3 ± 1.8 ng/ml) and FSH (8.1 ± 1.1 ng/ml) did not differ between Day 0 and Day 1 or between Day 0 and Day 2 (Table 2).

Secretion of LH and FSH in plasma samples collected every 10 min for 12 h showed a characteristic pulsatile pattern (Fig. 1 and Table 3). Methods used to identify episodic hormone secretion agree on LH pulse frequency and amplitude. However, FSH pulse frequency was higher when the mean + 1 SD was used when compared to the Pulsar and times-series analyses (Table 3). Pulses of LH were more frequent (0.54 pulses/h; average over methods) and had greater amplitude (6.8 ng/ml; average over methods) than FSH pulses (0.38 pulses/h, and 3.4 ng/ml, respectively; P < 0.01).

Only 32% of the LH pulses were associated with FSH episodes (Table 4). Moreover, 64% of the LH pulses were not associated with an FSH pulse, and 60% of the FSH pulses were not associated with any LH pulse. Figure 2 illustrates the dissociation between LH and FSH pulses in bird 2, in which blood samples were collected every 10 min over 12 h on Day 2.

Experiment 2. Concentrations of LH and FSH in plasma averaged 8.5 ± 0.5 and 7.7 ± 0.7 ng/ml, respectively. Secretion of LH and FSH in plasma samples collected every 10 min for 8 h showed a characteristic pulsatile pattern (Fig. 3). The LH and FSH pulse frequency (0.58 ± 0.08 and 0.36 ± 0.06 pulses/h, respectively) and amplitude (7.1 ± 0.81 and 3.7 ± 0.31 ng/ml, respectively) were similar to the results from experiment 1. Only 23% of the LH pulses were associated with FSH episodes (sensitivity) in experiment 2. Additionally, the false-positive rate (LH pulses not associated with an FSH pulses) was 59%, and the false-negative rate (FSH pulses not associated with an LH pulse) was 53%. Figure 3 illustrates the dissociation between LH and FSH pulses in birds used in experiment 2, in which blood samples were collected every 10 min for 8 h.

Testosterone

Average concentrations of testosterone in plasma tended to increase as the testis weight of individual birds increased (Table 1). Testosterone concentrations on Day 0 were 50% less than those on Day 1 and Day 2, a significant reduction (P < 0.1).

Testosterone was secreted in an episodic fashion, with an average of 0.33 ± 0.04 pulses/h (average over methods) and an amplitude of 1.2 ± 0.1 ng/ml (Fig. 1 and Table 3). The association between LH and testosterone pulses in birds 2, 3, and 4 averaged 83%, whereas sensitivity for bird 1 was only 23% (Table 4). Amplitude of LH pulses that were associated with a testosterone pulse was 6.4 ng/ml in birds 2, 3, and 4, compared with an LH pulse amplitude of only 2.8 ng/ml in those pulses that were not associated with a testosterone spike. However, in bird 1, no difference was found in the amplitude of LH pulses that either were or were not associated with a testosterone episode. Figure 4 illustrates the association between LH and testosterone in two birds with a significant difference in sensitivity.

Corticosterone

Concentrations of corticosterone in the single sample that was taken immediately before birds were cannulated averaged 0.6 ± 0.2 ng/ml (Day 0 Hour 1) (Fig. 5). Concentrations tended to increase after birds were cannulated and remained elevated for 3-4 h. By the end of Day 0, corticosterone returned to precannulation concentrations and remained low throughout Days 1 and 2 (Figs. 1 and 5). However, a high variation between birds was observed, and corticosterone concentrations in hourly samples during Day 0 were not significantly different from those on Day 1 or Day 2 (Table 2).

TABLE 1. Testis weight and average concentrations of LH, FSH, testosterone, and corticosterone in individual birds used in experiment 1.
table1Episodic Gonadotropin Secretion-1
* Corticosterone concentrations were evaluated in hourly samples during Days 0-2.

TABLE 2. Concentrations (ng/ml) for LH, FSH, testosterone, and corticosterone in plasma of male broiler breeders.*
table2Episodic Gonadotropin Secretion-2
* Values are presented as mean (SEM).
+ Corticosterone concentrations were evaluated in hourly samples during Days 0-2.

TABLE 3. Evaluation of different statistical methods to characterize LH, FSH, and testosterone pulse frequency, and amplitude in experiment 1.*
table3Episodic Gonadotropin Secretion-5
* Values are presented as the mean (SEM).
a,b Values with different letters in a row are significantly different (P < 0.05).

TABLE 4. Sensitivity, false-positive rate, and false-negative rate between LH and FSH and between LH and testosterone pulses in birds that were bled at 10-min intervals for 12 h on each of Day 1 and Day 2.
table4Episodic Gonadotropin Secretion-3

Fig1Episodic Gonadotropin Secretion-4
FIG. 1. Concentrations of LH, FSH, and testosterone in plasma of a representative male broiler breeder used in experiment 1 (bird 4). Blood samples were collected at 10-min intervals for 4 h on Day 0 and for 12 h on Day 1 and Day 2. Corticosterone concentrations were evaluated in hourly samples. Asterisks indicate the presence of a pulse of LH, FSH, or testosterone, as determined by Pulsar.

Fig2Episodic Gonadotropin Secretion-7
FIG. 2. Pulsatile secretion of LH and FSH in plasma of bird 2 in experiment 1. Blood samples were obtained every 10-min for 12 h during Day 2. Asterisks indicate the presence of a pulse of LH or FSH, as determined by Pulsar.

Fig3Episodic Gonadotropin Secretion-6
FIG. 3. Pulsatile secretion of LH and FSH in plasma of four birds used in experiment 2. Blood samples were obtained every 10-min for 8 h. Asterisks indicate the presence of a pulse of LH or FSH, as determined by Pulsar.

Fig4Episodic Gonadotropin Secretion-8
FIG. 4. Pulsat ile secret i on of LH and testosterone in plasma of b i rds used i n exper i ment 1. Blood samples were obta i ned every 10-m in for 12 h on b i rd 2 (Top; low sens i t iv i ty) and b i rd 3 (Bottom; h i gh sens i t iv i ty) dur ing Day 1. Asterisks indicate the presence of a pulse of LH or testosterone, as determined by Pulsar.

Fig5Episodic Gonadotropin Secretion-9
FIG. 5. Average plasma corticosterone concentration in experiment 1 during Days 0, 1, and 2. A single blood sample was obtained before cannulation, and hourly samples were obtained for 8 h on Day 0 and for 12 h on each of Day 1 and Day 2.

Category: Gonadotropin

Tags: anteriorpituitary, corticosterone, follicle-stimulatinghormone, lutein izing hormone, Testis

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