Trade-off expression of melatonin receptor subtypes (Mel1a and Mel1b) and androgen receptor in lung of a tropical bird, Perdicula asiatica

The role of circulatory steroid hormone along with melatonin in lung of any seasonally breeding bird has never been explored so far. This could be interesting because steroid hormones are immunosuppressive while melatonin is immunostimulatory in nature. In our present study, we report the effect of exogenous melatonin and testosterone on expression of melatonin receptor subtypes (Mel_1a and Mel_1b ) and androgen receptor in lung of a tropical bird Perdicula asiatica. Birds were collected from vicinity of Varanasi and acclimatized in laboratory with sufficient food and water. The birds were treated with melatonin and testosterone at dose of 25 µg/100 g B.wt./day and 1 mg/100 g B.wt./day, respectively, for 28 days. At the end of the experiment, the birds were sacrificed and lung tissue and blood sample were collected for immunohistochemistry, Western blot analysis and hormonal assay. Testosterone treatment increased circulatory testosterone and upregulated expression of androgen receptors whereas downregulated expression of melatonin receptor subtypes Mel_1a and Mel_1b . Melatonin administration increased peripheral melatonin and upregulated expression of melatonin receptor subtypes Mel_1a and Mel_1b while downregulated androgen receptor. Thus, our results suggest that a trade-off relationship between melatonin and testosterone exists in regulation of their receptors in lung of Perdicula asiatica.

Daily variation in antioxidant enzymes and lipid peroxidation in lungs of a tropical bird Perdicula asiatica: role of melatonin and nuclear receptor RORα

The wild animals are exposed in nature to more oxidative stress than any laboratory animals. Studies on oxidative stress of brain, liver and kidney are quite common while very less reports are available on respiratory system when it is the most susceptible organ to various stressors. We checked the oxidative stress of lung tissue of a wild seasonally breeding bird Perdicula asiatica by noting down the daily variation in antioxidant enzymes (superoxide dismutase and catalase) levels, lipid peroxidation in terms of malondialdehyde level and total antioxidant status during reproductively active (RAP) and inactive phase (RIP). On the other hand melatonin has been accepted as free radical scavenger acting via receptor (nuclear receptor) or non receptor pathway. To pin point the role of melatonin in regulation of antioxidant enzymes via non receptor mediated pathway in lungs of bird, we checked variation in the nuclear melatonin receptor RORα. Antioxidant enzymes (superoxide dismutase and catalase) exhibited a marked 24h rhythm in lungs being high during night time and coincided almost with the peak of melatonin and total antioxidant status where as malondialdehyde level and nuclear receptor RORα showed inverse relationship with all the above mentioned parameters. These findings suggest that melatonin might be acting as an antioxidant for the free radical load of lung tissue of a tropical bird P. asiatica and its action might be via nuclear receptor RORα.

Annual variation in lung associated immunity and season dependent invasion of Alternaria alternata in lungs of Indian jungle bush quail, Perdicula asiatica

The purpose of this study was to evaluate annual variation in lung associated immune system (LAIS) along with general immunity ofPerdiculaasiaticaan Indian tropical bird. Variation in immunological parameters such as size of bronchus associated lymphoid tissue (BALT) and non-BALT nodules, percent stimulation ratio (%SR) of isolated lung lymphocytes, total leukocyte count (TLC) and lymphocyte count (LC) was noted along with circulatory hormonal levels i.e. melatonin and testosterone for two consecutive years. Lowest immune status in terms of small BALT and non-BALT nodular size, %SR, TLC and LC was noted in the month of April. Considering the relation between annual variation of the peripheral hormones melatonin and testosterone and immune status of this bird, we observed an inverse relationship. It could be that high testosterone (an immunosuppressor) and low melatonin (an immunostimulator) levels during summer months are responsible for low immunity. While studying annual variation in LAIS we observed a fungal pathogenAlternaria alternatapresent in the lungs only during April suggesting that invasion occurred at a particular month of harvest (April). During the month of April low lung immune status was recorded, which could be responsible for such an invasion. This bird is a game bird and consumed as food by common rural people. If this fungus is being ingested along with the birds it may cause diseases like bronchitis, asthma, etc. in human being. Hence, gaming of this bird during summer month (April) should be avoided.