Thyroid responses to altered photoperiod in the soft-shelled turtle Lissemys punctata punctata bonnoterre.

The aim of the current investigation was to investigate the effect of photoperiod on thyroid activity in soft-shelled turtles (Lissemys punctata punctata). Thirty days exposure of short photoperiod with 2L:22D increased relative weight, follicular epithelial height and peroxidase activity of the thyroid gland; whereas exposure of long photoperiod with 22L:2D for 30 days showed reversed changes to those of the short photoperiod in adult female turtles. These findings indicate that short photoperiod stimulates thyroid activity and long photoperiod inhibits its activity in soft-shelled turtles. It is suggested that photoperiod exerts its action on thyroid activity presumably via gonads and/or pineal-gonadal axis in turtles.

Sarkar S ，Sengupta A ，Chaudhuri-Sengupta S ，Maiti BR ... -  《ACTA BIOLOGICA HUNGARICA》

Thyroidal inhibition following diverse stress in soft-shelled turtle, Lissemys punctata punctata bonnoterre.

The current study was undertaken to ascertain the effects of diverse stress on thyroid activity in soft-shelled turtles, Lissemys punctata punctata. The findings revealed that starvation (10 days), dehydration (10 days) or exposure to electric shock (12 volts for 15 seconds at an interval of 30 min for 3 h) caused significant decrease in the body weight (except in electric shock), relative weight, peripheral and central epithelial heights of the follicles and peroxidase activity of the thyroid gland of turtles. The degree of change in the values of these parameters was nearly same in all the stress experiments, indicating that there is not much difference in the degree of thyroid responses to diverse stress in turtles. It is suggested that these stressors might have exerted their actions on thyroid activity presumably indirectly via adrenal medulla and/or substance in metabolic stress (starvation and dehydration) and via hypothalamo-hypophysial-adrenocortical axis in non-metabolic stress (electric shock) in Lissemys turtles.

Ray PP ，Sengupta A ，Chaudhuri-Sengupta S ，Maiti BR ... -  《ACTA BIOLOGICA HUNGARICA》

Thyroidal modulation following hypo- and hyper-thermia in the soft-shelled turtle Lissemys punctata punctata Bonnoterre.

The aim of the current study was to investigate the effects of ambient temperature on thyroid activity of the soft-shelled turtle (Lissemys punctata pucntata). Turtles exposed to low ambient temperature (10 degrees C for 15 days) showed a significant decrease in relative thyroid weight, follicular cell size (cell became squamous from cuboidal type) and epithelial height in both the peripheral and central follicles of the gland, with the appearance of homogeneous colloid materials in the follicular lumen. Thyroid peroxidase activity declined significantly. In contrast, high ambient temperatures (32/34 degrees C for 15 days) caused reverse changes to those observed after exposure with low ambient temperature. No significant difference was marked in thyroid activity between 32 and 34 degrees C temperature treatments. The findings provide evidence that low ambient temperature inhibits thyroid activity and high ambient temperature stimulates the gland activity in soft-shelled turtles. Ambient temperature acts presumably via the hypothalamo-hypophysial (TRF-TSH) axis which in turn alters thyroid function in turtles.

Sengupta A ，Ray PP ，Chaudhuri-Sengupta S ，Maiti BR ... -  《-》

Melatonin action on thyroid activity in the soft-shelled turtle, Lissemys punctata punctata.

Sarkar S ，Sarkar NK ，Bhattacharyya S ，Das P ... -  《FOLIA BIOLOGICA-KRAKOW》

Roles of thyroid, adrenal and pancreatic hormones on thyroid activity of the soft-shelled turtles Lissemys punctata punctata Bonnoterre.

Ray PP ，Sarkar S ，Sengupta A ，Chaudhuri-Sengupta S ，Maiti BR ... -  《FOLIA BIOLOGICA-KRAKOW》