Pineal-adrenocortical interactions in domestic male pigeon exposed to long and short photoperiods and exogenous testosterone propionate

Abstract

Young adult male domestic pigeons were exposed to artificial long photoperiod (LP, 200 watt; 20 hr light, L : 4 hr dark, D), short photoperiod (SP; 4 L : 20 D) and administration of exogenous testosterone propionate (TP) at a daily dose of 1 mg/100 g body weight for 60 consecutive days in primary breeding and regressive phases-I. Administration of TP in LP and SP during primary breeding phase decreased both the adrenal and pineal gland weight. In the TP–LP treatment during breeding phase, adreno-cortical cord width, nuclear diameter of sub-capsular zone (SCZ), central zone (CZ), and pinealocytes decreased significantly. Cholesterol, ascorbic acid level, and side-chain cleavage enzyme (SCC) within the CZ regions also decreased. Lipid granules increased in the SCZ but decreased in the CZ region, and alkaline and acid phosphatases levels increased significantly. Dark and broad cristae and numbers of mitochondria (mt) decreased within the adreno-cortical regions. But lipid droplets and rough endoplasmic reticulum (rER) increased. Large numbers of dark and dead mitochondria and less number of free ribosomes were also found within the pinealocytes cytoplasm. Whereas, in TP–SP treatment groups during breeding phase, weight of adrenal and pineal glands decreased. Alkaline and acid phophatases levels also decreased. But, cholesterol and ascorbic acid level and intensity of lipids droplets increased within the SCZ region. On the other hand, owing to TP–LP treatment during regressive phase-I, weight of adrenal gland, adreno-cortical cord widths, and nuclear diameter of SCZ and CZ regions increased significantly. High intensities of SCC enzymes were found in both the SCZ and CZ regions as well. Lipid droplets and rER decreased but mitochondria increased in the adreno-cortical region. Cholesterol and ascorbic acid level and intensity of lipids droplets in both the SCZ and CZ regions decreased. But alkaline and acid phophatases levels increased. And weight of pineal gland and its nuclear diameter decreased. Here, free ribosomes and the number of mitochondria decreased. In the TP-SP treatment groups, there is no major change within the adrenal gland, adrenocortical regions, and SCC enzymes. Intensity of lipids droplets increased within the CZ region. The nuclear diameters of pinealocytes were smaller than control. Cholesterol and ascorbic acid levels also decreased and alkaline and acid phophatases levels increased when compared to that in control. The number of mitochondria, smooth endoplasmic reticulum (sER), and Golgi complex was the same as in control groups in both the adrenal and pineal glands. But mitochondria and rER increased in both the adrenal and pineal gland cytoplasm. The present studies on the male domestic pigeons clearly indicate that the activities of the adrenal and pineal glands during the regressive phases-I showed a clear relationship with the breeding birds. However, TP treatment in the birds during breeding phases showed some depressive results due to melatonin rhythm like the non-breeding or regressive phase of adult birds.

Keywords:

• adrenal
• melatonin
• photoperiod
• pineal
• pinealocyte
• testosterone propionate

Acknowledgements

This study was financially supported by the University of Kalyani (IF-1/2001/DP-993), West Bengal, India. The authors also thank Dr. T.C. Nag, AIIMS, India, for ultrastructural work, and Professor Bon-chu-Chung, Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, for immunohistochemical work.