Journal of Endocrinology and Reproduction

L. Divya ¹, M. A. Akbarsha ², M. M. Aruldhas ³, O. V. Oommen ¹

Affiliations
1 Dept of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, IN
2 Department of Animal Science, Bharathidasan University, Tiruchirappalli 620024, IN
3 Department of Endocrinology, Dr ALM PGIBMS, University of Madras, Taramani campus, Chennai 600113, IN

Abstract

Reactive oxygen species (ROS) are known to influence molecular and biochemical processes and signal transduction pathways, affecting cellular proliferation, differentiation and death in a variety of organisms. Amphibian metamorphosis encompasses all these three events within a short span of time. In the frog Clinotarsus curtipes development is largely akin to the post-embryonic development in mammals, displaying increased levels of ROS under in vivo physiological conditions. Scavenging ROS with an antioxidant revealed a serendipitous finding of turning to a pro-oxidant and a novel thyroid hormone mimetic with potential effects on neurotransmitter functions. Further, confirmatory studies, both conventional binding assays combined with in- silico approaches, revealed the ability of the compound to bind to human thyroid receptors thereby to mimic the thyroid hormone activity and thus function as potent endocrine disrupting chemical. Thus our study also cautions against the indiscriminate use of supplementary molecules without proper validation. Our studies on amphibian (Clinotarsus curtipes) development are valuable in examining the role of ROS in post embryonic development.

Keywords

Neurotransmitters, Metamorphosis, ROS, Oxidant.

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O. V. Oommen ¹, P. Sreejith ¹, R. S. Beyo ¹, L. Divya ¹, A. S. Vijayasree ¹, M. Manju ¹

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram-695 581, Kerala, IN

Abstract

Our studies describe the effect of T₃ on the regulation of mitochondrial metabolism, lipid peroxidation and antioxidant enzyme homeostasis in a fresh water teleost, Anabas testudineus. These experiments suggest the possibility that certain of the clinical and biochemical manifestations of T₃ can be attributed to a direct effect of T₃ on mitochondria. Thyroid hormone enhances mitochondrial ATP production rate in the highly oxidative tissue such as liver. These in vitro and in vivo studies substantiate and confirm the earlier reported T₃-induced oxidative metabolism in lower vertebrates. These induced oxidative metabolisms create oxidative stress in tissues. This confirms that T₃ has an immediate response in in vivo and in vitro system on energy adjustment in the fish, A. testudineus. Tri-iodothyronine is also capable of combating the oxidative stress by activating the antioxidant system to remove the ROS. Tri-iodothyronine appears to have a dual role, as a stimulator of oxidative process and as a regulator of antioxidant enzyme activity. This establishes another example for the multi-functional role of T₃ in lower vertebrates also. However, the precise mechanism of action remains to be understood. The protein expression study revealed that T₃ administration in fish creates hypermetaolic state. This hypermetabolic state creates oxidative stress in fish. To maintain the homeostasis of the fish, physiology the main antioxidant CuZn SOD is directly altered. Due to augmented SOD utilization, expression of CuZn SOD is diminished in fish liver and brain. These findings conclude that thyroid hormone effectively maintains physiological status of fresh water fish. It is obvious that thyroid hormones have an over all effect on metabolism in responsive tissue and that their effect is a direct one. Theses studies establish multi-functional role of T₃ in lower vertebrates.

Keywords

Anabas testudineus, Free Radicals, Mitochondrial Respiration, Superoxide Dismutase, Thyroid Hormone, Tri-Iodothyronine.

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R. S. Beyo ¹, L. Divya ¹, K. Ramachandran ¹, O. V. Oommen ¹, M. A. Akbarsha ²

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram, 695585, IN
2 Derpartment of Animal Science, Bharathidasan University, Thiruchirappalli, 620 024, IN

Abstract

Corpus luteum is a transient and well known endocrine gland that develops from the ruptured follicles in the female vertebrate ovaries, immediately after ovulation. A major source of progesterone, this gland is concerned with gestation in the viviparous animals and retention of eggs in the oviduct in the oviparous species. Caecilians are a group of amphibians with several aspects of reproductive anatomy and physiology unique. In as much as corpus lutem has been described in a few caecilian species, it has not been described from ultrastructural perspectives. Here in we describe the ultrastructural features of corpus luteum of a single specimen of Gegeneophis ramaswamii, which was captured immediately after it laid the eggs. The corpus luteum is formed by three types of cells, namely granulosa lutein cells, thecal lutein cells and phagocytic cells. Both the types of lutein cells are characterized by abundant mitochondria, endoplasmic reticulum and Golgi apparatus. The granulose lutein cells abound with discrete granules. The phagocytic cells engage in phagocytosing cell debris. The cellular features are discussed in relation to information from oviparous as well as viviparous vertebrates. Thus, the paper describes, for the first time the corpus luteum of a caecilian from ultrastructural perspectives.

Keywords

Corpus Luteum, Endothelium, Theca, SER, Follicle Cell.

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