Alenciks E, Frazier K, Porter A, Fraley G (2015) Immunolesions of melanopsin receptive neurons attenuates the hormonal reproductive axis in the adult but has no effect on growth in immature Peking ducks. Neuroscience 2015 Abstracts 613.05/R20. Society for Neuroscience, Chicago IL.
Summary: Several light sensitive receptors have been described in the avian brain that are thought to regulate the reproductive axis independently from the eyes and pineal gland. Recently, our lab has described the presence of 3 photoneuroendocrine systems in the Pekin duck: rhodopsin, opsin 5, & melanopsin. We set out to test the hypothesis that melanopsin receptive neurons are necessary to maintain seasonal reproductive status along with growth and development in the Pekin drake. To accomplish these goals we first investigated 50-week-old Pekin drakes that were housed in the aviary at Hope College under long day length (18 hrs lights on) conditions in floor pens. To specifically lesion melanopsin-receptive neurons, 3 μl of an anti-melanopsin-saporin conjugate (MSAP, 100 ng/ul) was injected into the lateral ventricle (n = 10). Control drakes were injected with 3 ul of equimolar unconjugated anti-melanopsin and saporin (SAP, n = 10). The drakes were returned to the aviary after complete recovery. Reproductive behaviors were analyzed weekly in a test pen with adult hens. After 4 weeks, birds were euthanized and body weights were measured, and brains, pituitaries, and testes collected and stored for analyses. To test melanopsin’s effect on immature ducks the same surgery was performed on a group of 10 day old ducks (n= 10). Ducks were weighed weekly starting at 3 days of age. After a final weight was obtained at 50 days of age, ducks were euthanized and a blood sample was collected and sent out for an avian panel. Mature MSAP-treated drakes had significantly (p< 0.001) reduced relative teste weights compared to SAP controls. qRT-PCR analyses (n= 3 per treatment) of anterior pituitary showed a significant reduction (p< 0.001) in both LH-beta and FSH mRNA’s. Immunoctyochemical analyses (n= 3 per treatment) showed a significant reduction in melanopsin and GnRH-immunoreactivities. Immature drake BW did not differ significantly between MSAP and SAP animals at any of the measured days. The data appeared to drift toward significance near the end of the sampling period (p = 0.297). Blood panel results revealed no significant differences between MSAP and SAP animals in any CBC component. Serum glutamic-oxaloacetic transaminase (SGOT) (p= 0.022) and creatine phosphokinase (CPK) values were significantly elevated (p = 0.006) in MSAP animals compared to controls. Although melanopsin neurons in the PMM appear to have an important role in adult drakes, their importance in the growth of immature ducks is still unclear. However, these data underscore the importance of the photoneuroendocrine system in maintaining the reproductive axis along with growth and development in seasonally breeding birds.
Related Products: Melanopsin-SAP (Cat. #IT-44), Saporin (Cat. #PR-01)