ARS | Publication request: EFFECT OF SULFAMETHAZINE AND PHOTOSTIMULATION ON GENE EXPRESSION OF VASOACTIVE INTESTINAL POLYPEPTIDE (VIP) AND PHOSPHODIESTERASE IN THE LATERAL SEPTAL ORGAN (LSO) AND PITUITARY GONADOTROPIN CONTENT IN THE CHICK.

Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: April 17, 2006
Publication Date: July 6, 2006
Citation: Li, H., Proudman, J.A., Kuenzel, W.J. 2006. Effect of sulfamethazine and photostimulation on gene expression of vasoactive intestinal polypeptide (vip)and phosphodiesterase in the lateral septal organ (lso) and pituitary gonadotropin content in the chick [abstract]. Poultry Science. Supplement 1. p. 44.

Technical Abstract: Most birds living in the temperate zone use seasonal changes in day length as predictive environmental cues to initiate and terminate breeding. Long day illumination induces rapid gonadal developmen tand stimulates gonadotropin-releasng hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH), and testosterone secretion in avian species. A group of non-retinal, non-pineal encephalic photoreceptors (EPRs) were hypothesized some time ago to sense external photoperiodic change. Two sites located in deep brain were suggested to house the potential EPRs, the LSO and the medial basal hypothalamus. Molecules identifi ed in the putative EPRs of the LSO and considered as critical components in the possible phototransduction pathway included rhodopsin, rod-type cGMP-phosphodiesterase #946;-subunit, and VIP. Of interest is that the combination treatment of sulfamethazine (SMZ), a compound that stimulates gonadal development, together with long day exposure signifi cantly increased plasma LH within 48 h. To elucidate whether and how SMZ and/or long day illumination affect the neuroendocrine system, a 2X2 factorial study was conducted in non-photostimulated or photostimulated and SMZ-fed or control diet-fed chickens. Pituitary content of prolactin (PRL) and gonadotropin were assayed and gene expression of rhodopsin, phosphodiesterase, and VIP in the LSO, as well as FSH and LH in the pituitary gland were quantitated using real time-PCR. SMZ treatment significantly increased pituitary content of LH at 16h, and decreased PRL at 12 h (n=5, p<0.05). Peak of LH and FSH mRNA level occurred as early as 6 h in pituitary, while at the level of brain, VIP and phosphodiesterase increased in the LSO following SMZ feeding at 4h and 6 h, respectively. The current study indicated that SMZ functions at a level higher than the pituitary gland in the photoneuroendocrine system, and it might affect the phototransduction cascade in the EPRs.