Dopamine and Norepinephrine in the Diencephalon of Ovariectomized and Sham‐Operated Hens Around Sexual Maturity

Abstract

Dopamine (DA) and norepinephrine (NE) in the diencephalon were quantified between 9.30 and 10.30 hours, at the age of 14, 18,20,22 and 26 weeks in sham-operated and ovariectomized hens. Average DA concentration in the diencephalon did not vary significantly between the sham-operated and ovariectomized hens among the various age groups studied. The values of NE in the diencephalon of sham-operated hens were significantly higher than in ovariectomized hens at their comparable age. A significant increase was noted at 20 weeks over that at 18 weeks in the sham-operated hens and this increase was not recorded at these age groups in the ovariectomized hens. No significant difference was recorded at 20, 22 or 26 weeks of age in the sham-operated hens. A significant elevation of NE concentration in the diencephalon around 20 weeks of age, when the ovarian follicles start to undergo a rapid stage of development, and a lack of this upsurge in ovariectomized hens indicated its physiological involvement at some stage in the process of gonadal maturity. The present study did not point towards the involvement of DA, since neither did its level vary between sham-operated and ovariectomized hens nor was an increase recorded around the rapid start of ovarian development. A highly significant positive correlation of NE in the diencephalon with ovarian (0.595) and oviduct (0.701) weights and absence of any significant correlation of DA again suggest the involvement of NE but not that of DA in the process of gonadal maturity.