Brief report: embryonic growth and hatching implications of developmental 670-nm phototherapy and dioxin co-exposure.
OBJECTIVE
We assessed the effect of 670-nm light therapy on growth and hatching kinetics in chickens (Gallus gallus) exposed to dioxin.


BACKGROUND
Photobiomodulation has been shown to stimulate signaling pathways resulting in improved energy metabolism, antioxidant production, and cell survival. In ovo treatment with 670-nm light-emitting diode (LED) arrays improves hatching success and increases hatchling size in control chickens. Under conditions where developmental dioxin exposure is above the lethality threshold (100 ppt), phototherapy attenuates dioxin-induced early embryonic death. We hypothesized that 670-nm LED therapy would attenuate dioxin-induced developmental anomalies and increase hatching success.


METHODS
Fertile chicken eggs were injected with control oil, 2, 20, or 200 ppt dioxin, or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) prior to the start of incubation. Half of the eggs in each dose group were treated once per day from embryonic days 0-20 with 670-nm LED light at a fluence of 4 J/cm2. Hatchling size, organ weights, and energy parameters were compared between dose groups and LED treatment.


RESULTS
LED therapy resulted in earlier pip times (small hole created 12-24 h prior to hatch), and increased hatchling size and weight in the 200 ppt dose groups. However, there appears to be an LED-oil interaction within the oil-treated controls that results in longer hatch times and decreased liver weight within the LED control dose groups in comparison to the non-LED control dose groups.


CONCLUSIONS
Size and hatching times suggest that the hatching success and preparedness of chicks developmentally exposed to dioxin concentrations above the lethality threshold is improved by 670-nm LED treatment administered throughout the gestation period, but the relationship may be complicated by an LED-oil interaction.
Yeager
Ronnie L
RL
School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana 47405, USA. rlyeager@indiana.edu
Franzosa
Jill A
JA
Millsap
Deborah S
DS
Lim
Jinhwan
J
Hansen
Corey M
CM
Jasevicius
Ashley V
AV
Heise
Stephen S
SS
Wakhungu
Phoebe
P
Whelan
Harry T
HT
Eells
Janis T
JT
Henshel
Diane S
DS
D000818:Animals; D002642:Chick Embryo / Q000196:embryology*; D002645:Chickens / Q000254:growth & development; D004147:Dioxins / Q000633:toxicity*; D008099:Liver / Q000196:embryology; D009929:Organ Size; D010789:Phototherapy
D004147:Dioxins