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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: Energy deficiency can suppress reproductive function in vertebrates.Wild-caught birds were either ad libitum fed or energetically constrained via chronic food restriction during photoinduced reproductive development.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

Schematic representation of the experiment. The change in photoperiod regime is indicated by the solid line, and the arrows show the timing of the experimental challenges. We first measured daily ad libitum food consumption of each bird, then food restricted half of the birds for the remainder of the experiment by giving them 70% of daily ad libitum consumption per day, resulting in a 15% body mass decrease. The experimental challenges began at time 0. SD hormone challenges consisted of measuring the plasma testosterone response to both GnRH and LH during short days (10 h light:14 h dark), and LD hormone challenges consisted of measuring this response during long days (16 h light:8 h dark). Giving-up-density (GUD) was measured as birds were transferred to long days.
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JEB123042F5: Schematic representation of the experiment. The change in photoperiod regime is indicated by the solid line, and the arrows show the timing of the experimental challenges. We first measured daily ad libitum food consumption of each bird, then food restricted half of the birds for the remainder of the experiment by giving them 70% of daily ad libitum consumption per day, resulting in a 15% body mass decrease. The experimental challenges began at time 0. SD hormone challenges consisted of measuring the plasma testosterone response to both GnRH and LH during short days (10 h light:14 h dark), and LD hormone challenges consisted of measuring this response during long days (16 h light:8 h dark). Giving-up-density (GUD) was measured as birds were transferred to long days.

Mentions: After all birds were transferred over 7 days to a maintenance diet (Mazuri small bird maintenance diet, PMI Nutrition International, Richmond, IN, USA), the daily food consumption of each individual was monitored for 1 week (Fig. 5). This was done by providing each bird with a known amount of food and measuring the amount that remained 24 h later, both in the food bowl and on the cage floor. After this 1 week monitoring period, we randomly assigned birds to one of two treatment groups: (1) ad libitum food availability or (2) restricted food availability. Birds in the restricted group were given a food ration equal to 70% of their daily ad libitum food consumption. We selected this restriction regime based on previous studies on Abert's towhees that demonstrated that a diet of 70% of daily ad libitum consumption reduces body mass by approximately 15% (Davies et al., 2015a). In order to maintain a 15% reduction in body mass, we weighed birds daily to the nearest 0.5 g. If a bird's mass dropped below its target mass, we immediately fed it the difference (in grams) between its current mass and its target mass. All food-restricted birds reached their target mass after approximately 7–10 days of food restriction.Fig. 5.


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)

Schematic representation of the experiment. The change in photoperiod regime is indicated by the solid line, and the arrows show the timing of the experimental challenges. We first measured daily ad libitum food consumption of each bird, then food restricted half of the birds for the remainder of the experiment by giving them 70% of daily ad libitum consumption per day, resulting in a 15% body mass decrease. The experimental challenges began at time 0. SD hormone challenges consisted of measuring the plasma testosterone response to both GnRH and LH during short days (10 h light:14 h dark), and LD hormone challenges consisted of measuring this response during long days (16 h light:8 h dark). Giving-up-density (GUD) was measured as birds were transferred to long days.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

JEB123042F5: Schematic representation of the experiment. The change in photoperiod regime is indicated by the solid line, and the arrows show the timing of the experimental challenges. We first measured daily ad libitum food consumption of each bird, then food restricted half of the birds for the remainder of the experiment by giving them 70% of daily ad libitum consumption per day, resulting in a 15% body mass decrease. The experimental challenges began at time 0. SD hormone challenges consisted of measuring the plasma testosterone response to both GnRH and LH during short days (10 h light:14 h dark), and LD hormone challenges consisted of measuring this response during long days (16 h light:8 h dark). Giving-up-density (GUD) was measured as birds were transferred to long days.
Mentions: After all birds were transferred over 7 days to a maintenance diet (Mazuri small bird maintenance diet, PMI Nutrition International, Richmond, IN, USA), the daily food consumption of each individual was monitored for 1 week (Fig. 5). This was done by providing each bird with a known amount of food and measuring the amount that remained 24 h later, both in the food bowl and on the cage floor. After this 1 week monitoring period, we randomly assigned birds to one of two treatment groups: (1) ad libitum food availability or (2) restricted food availability. Birds in the restricted group were given a food ration equal to 70% of their daily ad libitum food consumption. We selected this restriction regime based on previous studies on Abert's towhees that demonstrated that a diet of 70% of daily ad libitum consumption reduces body mass by approximately 15% (Davies et al., 2015a). In order to maintain a 15% reduction in body mass, we weighed birds daily to the nearest 0.5 g. If a bird's mass dropped below its target mass, we immediately fed it the difference (in grams) between its current mass and its target mass. All food-restricted birds reached their target mass after approximately 7–10 days of food restriction.Fig. 5.

Bottom Line: Energy deficiency can suppress reproductive function in vertebrates.Wild-caught birds were either ad libitum fed or energetically constrained via chronic food restriction during photoinduced reproductive development.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