Table 4 Experimental studies of melatonin effects on fetal growth and brown adipose tissue accumulation/function
From: Neonatal lamb mortality: major risk factors and the potential ameliorative role of melatonin
Publication | Methodology | Melatonin dose rate/timing | Fetal/lamb outcomes |
|---|---|---|---|
Seron-Ferre et al. [67] | • Daily lighting schedule manipulation from ~gD93 until term • Lambs instrumented 2 d post-partum • 4–6 d post-partum: lambs exposed to 24 °C for 1 h, 4 °C for 1 h, 24 °C for 1 h before BAT collected for analysis | • Oral to ewe: 12 mg daily at 17:00 h from ~gD93 until term • Treatments:  - LD: 12 h light + 12 h dark  - LL: 24 h constant light  - LL + MEL: 24 h constant light + melatonin | In LL + MEL lambs compared with LL: • Higher birthweight (4.30 ± 0.18 kg) vs. LL (3.68 ± 0.33 kg) and LD (3.85 ± 0.27 kg) • Normalised BAT and skin temperature at thermoneutral (24 °C) and cold (4 °C) ambient temperatures (similar to control) • Mitigated increase to norepinephrine level during cold exposure (4 °C) • Normalised perirenal BAT weight (similar to control) • Ex vivo: Normalised bat function (LL exhibited increased basal lipolysis, no response to norepinephrine, and increased expression of adipogenic/thermogenic and clock genes) |
Sales et al. [68] | • Commercial grazing conditions on natural pasture • Fetal analysis at gD140 | • Subcutaneous to ewe: 18 mg per slow-release implant (Regulin®) at gD100 • Treatments:  - MEL0: control  - MEL1: one implant (18 mg)  - MEL2: two implants (36 mg) | In fetuses: • Singletons: BAT weight 18% higher in MEL2 fetuses vs. both MEL0 and MEL1 • Twins: BAT weight 35% higher in MEL1 fetuses vs. both MEL0 and MEL2 • All litter sizes: MEL2 fetuses 5–8% heavier with larger thorax diameter and crown-rump length vs. both MEL0 and MEL1 |
Sales et al. [69] | • Commercial grazing conditions on natural pasture • Fetal analysis at gD140 | • Subcutaneous to ewe: 18 mg per slow-release implant (Regulin®) at gD100 • Treatments:  - M0: control  - M1: one implant (18 mg)  - M2: two implants (36 mg) | In fetuses: • MEL2 male twins 14% or 22% heavier than MEL0 and MEL1, respectively • All litter sizes: MEL2 umbilical cord PO2 18–20% higher vs. both M0 and M1 |