Behaviour of the adrenal medulla using altered photoperiodic regimens during different phases of the annual testicular cycle in blossomheaded parakeet,Psittacula cyanocephala

Abstract

Abstract Adult male blossomheaded parakeets were held under artificial long (22 h) and short (2 h) daily photoperiods for 45 days or 90 days at different phases of the annual gonadal cycle to investigate the influences of altered photoperiods on the behaviour of the adrenal medulla in these birds. Results of the quantitative estimation of epinephrine (E) and norepinephrine (NE), counting of the tinctorially differentiated E and NE cells and cytofluorescence of NE containing areas in the adrenal medulla, have indicated that adrenomedullary response to a particular light‐dark schedule is uniform throughout the reproductive cycle of the parakeet. It has been found that significant (P < 0.001) loss of NE occurs only after 45 days treatment of very short daily photoperiods (2 L: 22 D), but the adrenal medulla of the rest of the experimentally treated birds remains essentially similar to the chromaffin tissue of birds held parallely under natural photoperiods. The results indicate that long daily artificial dar...