Leptin inhibits ingestive behavior and induces diuresis and natriuresis. To examine
whether leptin influences fetal physiologic functions, we investigated the effect
of central leptin on ovine fetal swallowing activity and urine flow. Six pregnant
ewes with singleton fetuses (130 ± 2 d gestation) were prepared with maternal and
fetal arterial and venous catheters, fetal lateral intra-ventricle cannula, fetal
bladder and amniotic fluid catheters. Electromyogram wires were placed in the fetal
thyrohyoid muscle and upper and lower nuchal esophagus and electrodes were implanted
on the parietal dura. Five days after surgery, recombinant human leptin was infused
into the lateral ventricle and the fetus monitored for 8 h. Central leptin increased
fetal swallowing activity during low-voltage electrocortical activity from basal values
(0.96 ± 0.08 swallows/min) at 2 h (1.41 ± 0.24 swallows/min), 4 h (2.81 ± 0.57 swallows/min),
6 h (2.53 ± 0.59 swallows/min) and 8 h (2.08 ± 0.39 swallows/min, p < 0.05). In comparison
to basal values, low voltage electrocortical activity decreased (57 ± 5 % to 42 ±
4 %) and high voltage electrocortical increased (43 ± 5 % to 61 ± 4 %). In response
to leptin, fetal urine flow initially decreased from basal values at 2 h (0.12 ± 0.03
to 0.08 ± 0.02 ml/kg/min, p < 0.05) then subsequently increased at 4 h and 6 h (0.20
± 0.04; 0.21 ± 0.04 ml/kg/min, respectively, p < 0.05). Central leptin significantly
increases near term ovine fetal swallowing activity and urine output, suggesting that
leptin contributes to in utero development of ingestive behavior.
Key words:
OB Protein - Renal - Fetal Sheep - Swallowing - Thirst - Behavioral State
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