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d24-hour changes in circulating prolactin, follicle-stimulating hormone, luteinizing hormone and testosterone in male rats subjected to social isolation.

Esquifino AI, Chacón F, Jimenez V, Reyes Toso CF, Cardinali DP - J Circadian Rhythms (2004)

Bottom Line: METHODS: Animals were either individually caged or kept in groups (4-5 animals per cage) under a 12:12 h light-dark cycle (lights on at 0800 h) for 30 days starting on day 35 of life.RESULTS: Isolation brought about a decrease in prolactin, LH and testosterone secretion and an increase of FSH secretion.Secretion of prolactin, LH and testosterone decreases, and secretion of FSH increases, in isolated rats.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina. cardinal@mail.retina.ar

ABSTRACT
BACKGROUND: This work analyzes the effect of social isolation (a mild stressor) on the 24-h variation of pituitary-testicular function in young Wistar rats, assessed by measuring circulating levels of prolactin, FSH, LH and testosterone. METHODS: Animals were either individually caged or kept in groups (4-5 animals per cage) under a 12:12 h light-dark cycle (lights on at 0800 h) for 30 days starting on day 35 of life. Rats were killed at 4-h intervals during a 24-h cycle, beginning at 0900 h. RESULTS: Isolation brought about a decrease in prolactin, LH and testosterone secretion and an increase of FSH secretion. In isolated rats the 24-h secretory pattern of prolactin and testosterone became modified, i.e., the maximum in prolactin seen in control animals at the beginning of the activity span was no longer detected, whereas the maximum in circulating testosterone taking place at 1700 h in controls was phase-delayed to 2100 h in isolated rats. CONCLUSION: Social isolation affects the 24-h variation of pituitary-testicular function in young rats. Secretion of prolactin, LH and testosterone decreases, and secretion of FSH increases, in isolated rats. The maximum in prolactin seen in group-caged rats at the beginning of the activity span is not observed in isolated rats. The maximum in circulating testosterone taking place at the second part of the rest span in controls is phase-delayed to the light-dark transition in isolated rats.

No MeSH data available.


Related in: MedlinePlus

Effect of isolation on 24-h changes of plasma prolactin concentration in young male rats. Groups of 6–8 rats were killed by decapitation at 6 different time intervals throughout a 24 h cycle. Values at 0900 point are repeated on the "second" day. Bar indicates scotophase duration. Shown are the means ± SEM. Letters indicate the existence of significant differences between time points within each group after a Tukey-Kramer's multiple comparisons test, as follows: a p < 0.01 vs. 0900, 1300, 0100 and 0500 h. For further statistical analysis, see text.
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Figure 1: Effect of isolation on 24-h changes of plasma prolactin concentration in young male rats. Groups of 6–8 rats were killed by decapitation at 6 different time intervals throughout a 24 h cycle. Values at 0900 point are repeated on the "second" day. Bar indicates scotophase duration. Shown are the means ± SEM. Letters indicate the existence of significant differences between time points within each group after a Tukey-Kramer's multiple comparisons test, as follows: a p < 0.01 vs. 0900, 1300, 0100 and 0500 h. For further statistical analysis, see text.

Mentions: Figure 1 shows the levels of prolactin throughout the day in isolated and control rats. A factorial ANOVA for main effects indicated a significant 74% decrease of circulating prolactin in isolated rats (F1,75= 75.9, p < 0.00001) and the occurrence of significant time of day changes (F5,75= 18.8, p < 0.00001). The maximum seen in control animals at the beginning of the activity span was no longer detected in isolated rats (Fig. 1), as indicated both by a significant interaction between time of day and the experimental procedure in the factorial ANOVA (F5,75= 9.23, p < 0.00001) and by post-hoc Tukey-Kramer's tests (Fig. 1).


d24-hour changes in circulating prolactin, follicle-stimulating hormone, luteinizing hormone and testosterone in male rats subjected to social isolation.

Esquifino AI, Chacón F, Jimenez V, Reyes Toso CF, Cardinali DP - J Circadian Rhythms (2004)

Effect of isolation on 24-h changes of plasma prolactin concentration in young male rats. Groups of 6–8 rats were killed by decapitation at 6 different time intervals throughout a 24 h cycle. Values at 0900 point are repeated on the "second" day. Bar indicates scotophase duration. Shown are the means ± SEM. Letters indicate the existence of significant differences between time points within each group after a Tukey-Kramer's multiple comparisons test, as follows: a p < 0.01 vs. 0900, 1300, 0100 and 0500 h. For further statistical analysis, see text.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC373458&req=5

Figure 1: Effect of isolation on 24-h changes of plasma prolactin concentration in young male rats. Groups of 6–8 rats were killed by decapitation at 6 different time intervals throughout a 24 h cycle. Values at 0900 point are repeated on the "second" day. Bar indicates scotophase duration. Shown are the means ± SEM. Letters indicate the existence of significant differences between time points within each group after a Tukey-Kramer's multiple comparisons test, as follows: a p < 0.01 vs. 0900, 1300, 0100 and 0500 h. For further statistical analysis, see text.
Mentions: Figure 1 shows the levels of prolactin throughout the day in isolated and control rats. A factorial ANOVA for main effects indicated a significant 74% decrease of circulating prolactin in isolated rats (F1,75= 75.9, p < 0.00001) and the occurrence of significant time of day changes (F5,75= 18.8, p < 0.00001). The maximum seen in control animals at the beginning of the activity span was no longer detected in isolated rats (Fig. 1), as indicated both by a significant interaction between time of day and the experimental procedure in the factorial ANOVA (F5,75= 9.23, p < 0.00001) and by post-hoc Tukey-Kramer's tests (Fig. 1).

Bottom Line: METHODS: Animals were either individually caged or kept in groups (4-5 animals per cage) under a 12:12 h light-dark cycle (lights on at 0800 h) for 30 days starting on day 35 of life.RESULTS: Isolation brought about a decrease in prolactin, LH and testosterone secretion and an increase of FSH secretion.Secretion of prolactin, LH and testosterone decreases, and secretion of FSH increases, in isolated rats.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina. cardinal@mail.retina.ar

ABSTRACT
BACKGROUND: This work analyzes the effect of social isolation (a mild stressor) on the 24-h variation of pituitary-testicular function in young Wistar rats, assessed by measuring circulating levels of prolactin, FSH, LH and testosterone. METHODS: Animals were either individually caged or kept in groups (4-5 animals per cage) under a 12:12 h light-dark cycle (lights on at 0800 h) for 30 days starting on day 35 of life. Rats were killed at 4-h intervals during a 24-h cycle, beginning at 0900 h. RESULTS: Isolation brought about a decrease in prolactin, LH and testosterone secretion and an increase of FSH secretion. In isolated rats the 24-h secretory pattern of prolactin and testosterone became modified, i.e., the maximum in prolactin seen in control animals at the beginning of the activity span was no longer detected, whereas the maximum in circulating testosterone taking place at 1700 h in controls was phase-delayed to 2100 h in isolated rats. CONCLUSION: Social isolation affects the 24-h variation of pituitary-testicular function in young rats. Secretion of prolactin, LH and testosterone decreases, and secretion of FSH increases, in isolated rats. The maximum in prolactin seen in group-caged rats at the beginning of the activity span is not observed in isolated rats. The maximum in circulating testosterone taking place at the second part of the rest span in controls is phase-delayed to the light-dark transition in isolated rats.

No MeSH data available.


Related in: MedlinePlus