Gene Expression of Arginine Vasotocin in Ovarian and Uterine Tissues of the Chicken

The hypothalamus is the classic site of synthesis of arginine vasotocin as neurohypophyseal hormone in the chicken. However, high concentrations of arginine vasotocin were also measured in ovarian tissues by radioimmunoassay. At first, we observed specific positive signal of rnRNA encoding AVT in the hypothalamus by Northern hybridization. However, we could not find any specific bands in ovarian and uterine tissues. For evidence of transcription of the arginine vasotocin gene in gonadal tissues of the chicken, this study has applied the polymerase chain reaction as a highly sensitive assay. The hypothalamus, the four largest preovulatory ovarian follicles and the shell gland (uterus) were collected at 4 h and 20 h before oviposition. The ovarian follicular tissues were separated into granulosa theca interns and theca extern a layers. The uterine tissues were separated into myometrium and endometrium The extracted mRNA was converted to cDNA by reverse-transcriptase using oligo-d(T)₁₅ primer. Then, the cDNA was amplified by Vent polymerase and arginine vasotocin specific primers. The amplification reaction was incubated by 30 cycles successively, 95°C, 55°C and 72°C earth for 1 min. The comparisons of the mRNA levels encoding arginine vasotocin between the tissues were determined by semi-quantification methods. After amplification of the cDNA, the PCR products were detected in hypothalamus, ovarian tissues and uterine tissues. The results of semi-quantification showed that the levels of arginine vasotocin mRNA in ovarian iud uterine tissues were about from 1/50 to 1/1000 when compared to that in the hypothalamus. The very low levels of mRNA encoding arginine vasotocin in ovarian and uterine tissues probably led us to conclude that arginine vasotocin may play a role of local mediate acting autocrine and/or paracrine.