Survivorship and mortality implications of developmental 670-nm phototherapy: dioxin co-exposure.
OBJECTIVE
We assessed the effect of 670-nm light therapy on dioxin-induced embryonic mortality in chickens (Gallus gallus).


BACKGROUND
Developmental photobiomodulation using 670-nm light-emitting diode (LED) arrays improves hatching success and increases body size in hatchling chickens. Photobiomodulation also stimulates signaling pathways resulting in improved energy metabolism, antioxidant production and cell survival. Dioxin causes embryonic mortality, including increases in the frequency of chicken embryos that pip but can't go to hatch. We hypothesized that 670-nm LED therapy would attenuate dioxin-induced embryo mortality.


METHODS
Fertile chicken eggs were injected with control or 2, 20, or 200 ppt 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin) 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/cm(2). In ovo survival and hatching success were compared between dose groups and LED treatment.


RESULTS
LED therapy decreased the embryonic mortality rate by 41%, resulting in increased embryonic survival and improved hatching success in eggs exposed to 200 ppt dioxin. However, at sub-lethal dioxin concentrations and in oil-treated controls, LED therapy slightly increased mortality.


CONCLUSIONS
Overall survivorship and hatching success of chicks developmentally exposed to dioxin concentrations above the lethality threshold (>100 ppt TCDD) 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, 341 SPEA Building, 1315 East Tenth Street, Bloomington, IN 47405, USA. rlyeager@indiana.edu
Franzosa
Jill A
JA
Millsap
Deborah S
DS
Lim
Jinhwan
J
Heise
Stephen S
SS
Wakhungu
Phoebe
P
Whelan
Harry T
HT
Eells
Janis T
JT
Henshel
Diane S
DS
D000818:Animals; D002642:Chick Embryo / Q000254:growth & development* / Q000528:radiation effects*; D010789:Phototherapy; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D013723:Teratogens / Q000633:toxicity*
D000072317:Polychlorinated Dibenzodioxins; D013723:Teratogens