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Negative energy balance in a male songbird, the Abert's towhee, constrains the testicular endocrine response to luteinizing hormone stimulation.

Davies S, Gao S, Valle S, Bittner S, Hutton P, Meddle SL, Deviche P - J. Exp. Biol. (2015)

Bottom Line: As the orchestrator of reproductive function, endocrine activity of the hypothalamo-pituitary-gonadal (HPG) axis is potentially an important mechanism mediating such effects.Previous experiments in wild-caught birds found inconsistent relationships between energy deficiency and seasonal reproductive function, but these experiments focused on baseline HPG axis activity and none have investigated the responsiveness of this axis to endocrine stimulation.Collectively, these observations suggest that energy deficiency has direct gonadal effects consisting of a decreased responsiveness to LH stimulation.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA Scott.Davies@asu.edu.

No MeSH data available.


Related in: MedlinePlus

Effect of LH and gonadotropin-releasing hormone (GnRH) challenge on plasma testosterone. Adult male Abert's towhees were either ad libitum fed (N=9) or food restricted (70% of ad libitum consumption; N=8), and received both a GnRH challenge (A) and a LH challenge (B) while exposed to short days and again while exposed to long days. Food restriction suppressed the plasma testosterone response to a LH challenge, but there was no significant effect on a GnRH challenge. Data points are means±s.e.m., and points with identical letters are not significantly different (P>0.05, Tukey's HSD test).
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JEB123042F3: Effect of LH and gonadotropin-releasing hormone (GnRH) challenge on plasma testosterone. Adult male Abert's towhees were either ad libitum fed (N=9) or food restricted (70% of ad libitum consumption; N=8), and received both a GnRH challenge (A) and a LH challenge (B) while exposed to short days and again while exposed to long days. Food restriction suppressed the plasma testosterone response to a LH challenge, but there was no significant effect on a GnRH challenge. Data points are means±s.e.m., and points with identical letters are not significantly different (P>0.05, Tukey's HSD test).

Mentions: Plasma testosterone was affected by the two-way interaction between GnRH challenge and food availability (F1,16=10.34, P=0.005), and GnRH challenge and photoperiod (F1,16=11.86, P=0.003; Fig. 3A). Under SD, GnRH challenge significantly increased plasma testosterone in ad libitum-fed birds, but not in food-restricted birds. Under LD, GnRH challenge increased plasma testosterone by a similar degree in both ad libitum-fed and food-restricted birds. GnRH challenge increased plasma testosterone in ad libitum-fed and food-restricted LD-exposed birds to a higher level compared with ad libitum-fed and food-restricted SD-exposed birds.Fig. 3.


Negative energy balance in a male songbird, the Abert's towhee, constrains the testicular endocrine response to luteinizing hormone stimulation.

Davies S, Gao S, Valle S, Bittner S, Hutton P, Meddle SL, Deviche P - J. Exp. Biol. (2015)

Effect of LH and gonadotropin-releasing hormone (GnRH) challenge on plasma testosterone. Adult male Abert's towhees were either ad libitum fed (N=9) or food restricted (70% of ad libitum consumption; N=8), and received both a GnRH challenge (A) and a LH challenge (B) while exposed to short days and again while exposed to long days. Food restriction suppressed the plasma testosterone response to a LH challenge, but there was no significant effect on a GnRH challenge. Data points are means±s.e.m., and points with identical letters are not significantly different (P>0.05, Tukey's HSD test).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4582157&req=5

JEB123042F3: Effect of LH and gonadotropin-releasing hormone (GnRH) challenge on plasma testosterone. Adult male Abert's towhees were either ad libitum fed (N=9) or food restricted (70% of ad libitum consumption; N=8), and received both a GnRH challenge (A) and a LH challenge (B) while exposed to short days and again while exposed to long days. Food restriction suppressed the plasma testosterone response to a LH challenge, but there was no significant effect on a GnRH challenge. Data points are means±s.e.m., and points with identical letters are not significantly different (P>0.05, Tukey's HSD test).
Mentions: Plasma testosterone was affected by the two-way interaction between GnRH challenge and food availability (F1,16=10.34, P=0.005), and GnRH challenge and photoperiod (F1,16=11.86, P=0.003; Fig. 3A). Under SD, GnRH challenge significantly increased plasma testosterone in ad libitum-fed birds, but not in food-restricted birds. Under LD, GnRH challenge increased plasma testosterone by a similar degree in both ad libitum-fed and food-restricted birds. GnRH challenge increased plasma testosterone in ad libitum-fed and food-restricted LD-exposed birds to a higher level compared with ad libitum-fed and food-restricted SD-exposed birds.Fig. 3.

Bottom Line: As the orchestrator of reproductive function, endocrine activity of the hypothalamo-pituitary-gonadal (HPG) axis is potentially an important mechanism mediating such effects.Previous experiments in wild-caught birds found inconsistent relationships between energy deficiency and seasonal reproductive function, but these experiments focused on baseline HPG axis activity and none have investigated the responsiveness of this axis to endocrine stimulation.Collectively, these observations suggest that energy deficiency has direct gonadal effects consisting of a decreased responsiveness to LH stimulation.

View Article: PubMed Central - PubMed

Affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA Scott.Davies@asu.edu.

No MeSH data available.


Related in: MedlinePlus