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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J. Leji ¹, G. S. Babitha ², V. Rejitha ¹, A. S. Vijayasree ¹, J. Ignatius ², V. S. Peter ², O. V. Oommen ¹, M. C. S. Peter ¹

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, Kerala, IN
2 Department of Zoology, Fatima Mata National College, Kollam 695001, Kerala, IN

Abstract

The coconut husk retting in the backwaters of Kerala in Southern India, releases toxic effluents (CHRE), which pose a threat to the life of many inhabitants including fish. The indices of osmoregulatory activity and the levels of plasma triiodothyronine (T₃) and thyroxine (T₄) in the Mozambique tilapia Oreochromis mossambicus were quantified after exposing them to the effluents to understand the physiological mechanism of tolerance. The plasma glucose, an indicator of catecholamine secretion, remained unchanged in the tilapia exposed to CHRE. The plasma T₄ significantly increased in the tilapia kept in CHRE-rich water, though it declined in the fish kept for recovery in lake water. The plasma K⁺ significantly decreased in the tilapia treated with CHRE, which returned to the basal levels in those kept for recovery. The Na⁺, Ca²⁺ and PO₄^3- remained the same in both treated and untreated fish. The branchial Na⁺, K⁺-ATPase activity increased in the CHRE-exposed fish, and such an effect was not reversed in the recovery group. The renal Na⁺, K⁺-ATPase activity decreased in the lake water-exposed tilapia but not in the CHRE-treated fish. A reversal in the renal Na⁺, K⁺-ATPase activity was obtained in the tilapia kept for recovery in lake water. The intestinal Na⁺, K⁺-ATPase activity significantly declined in the CHRE-exposed tilapia but not in the recovery group. The data indicate that the presence of CHRE in lake water affects the osmoregulatory potential of tilapia without influencing their metabolic status. The up-regulated thyroid activity in the CHRE-exposed tilapia points to its involvement in the ion homeostasis during CHRE intoxication.

Keywords

Coconut Husk Retting, Fish, Metabolism, Oreochromis mossambicus, Stress, Thyroid Hormones, Tilapia.

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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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S. Leena ¹, B. Shameena ¹, O. V. Oommen ¹

Affiliations
1 Division of Endocrinology and Biochemistry, Department of Zoology, University of Kerala, Trivandrum 695 581, IN

Abstract

The hormonal control of lipid metabolism in heterotherms has received scant attention. The aim of this study was to evaluate the alterations in lipid components by ovine growth hormone (oGH) in a teleost Anabas testudineus. To study the role of oGH, three doses of oGH were given as intraperitoneal injections (0.1, 0.2, 0.5μg/g body wt/ day). Ovine GH at the higher doses significantly reduced serum cholesterol and LDL+VLDL, while increasing HDL. The concentrations of liver free fatty acids, triglycerides and cholesterol decreased and phospholipids increased in hormone treated specimens. Muscle triglycerides and cholesterol were increased after GH treatment. The results suggest the ability of oGH to break down neutral fat or oGH stimulates hepatic lipid mobilization in A. testudineus. Increased concentration of RNA suggests the ability of oGH to increase protein synthesis. Growth hormone appears to be antilipogenic and anabolic in A. testudineus.

Keywords

Anabas, Cholesterol, Free Fatty Acids, Growth Hormone, Phospholipids, RNA, Triglycerides.

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O. V. Oommen ¹, Sunny Francis ²

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Trivandrum 695 581, Kerala, IN
2 Department of Zoology, University College, Palayam, Trivandrum 695 034, Kerala, IN

Abstract

The recent development of diverse biological techniques at molecular levels has cause and explosive rise in our knowledge of production of hormones, their biological functions and modes of action. Steroid effects are typically slow in relation to the rapid time courses for effect of second messenger mediated peptide hormones. These types of slow and transcriptional action of steroids are termed genomic.

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O. V. Oommen ¹, M. Smita ¹, R. S. Beyo ¹, M. G. Jancy ², R. Girija ², M. A. Akbarsha ²

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, 695 581, Thiruvananthapuram, IN
2 Department of Animal Science, Bharathidasan University, Thinjchirappalli- 620 024, IN

Abstract

Caecilians, of the order Gymnophiona in the Lissamphibia, are circumtropically distributed across most moist tropical regions of the world. Gymnophiona are among the least understood terrestrial vertebrates and have received lesser attention than the other two orders of lissamphibians, the Urodela and Anura. Spermiogenesis, known as spermateleosis in lower vertebrates, is the transformation of the round spermatid into a highly specialized spermatozoon with a species-specific structure. Spermateleosis and sperm morphology of two species of caecilians, Ichthyophis tricolor and Uraeotyphlus cf. narayani, from the Western Ghats of Kerala, India, were studied using light and scanning electron microscopy. The cyst morphology is described in ten steps. We also report the sperm transporting course in this enigmatic amphibian in addition to localizing sperm in the kidney. This confirms the transport of sperm through the kidney.

Keywords

Amelwid Cells, Caecilians, Connective Tissue Strand, Cyst, Sertoli Cells, Spermatids, Spermatozoa, Sperm Transport.

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M. Smita ¹, O. V. Oommen ¹, M. G. Jancy ², M. A. Akbarsha ²

Affiliations
1 Department of Zoology, University of Kerala, Kariavottom 695 581, Trivandrum, Kerala, IN
2 Department of Animal Sciences, Bharathidasan University, Thiruchirappalli 620 024, Tamil Nadu, IN

Abstract

The Gymnophiona are the least wellknown amphibian order, an unfortunate situation because these animals can clarify many aspects of amphibian natural history, vertebrate evolution and the physiology of viviparity and fossorial life.

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S. Francis ¹, R. N. Binitha ¹, R. Indulekha ¹, O. V. Oommen ²

Affiliations
1 Department of Zoology, University College, Palayam, Trivandrum 695 034, IN
2 Department of Zoology, University of Kerala, Kariavottom, Trivandrum 695 581, IN

Abstract

Over the past decade, it has become evident that the brain is a steroidogenic organ. The actions of hormones in the brain play important roles during early development and in the process of sexual differentiation. The effects of steroid hormones on dendritic morphology, synaptic function and ionic conductance have been implicated in the regulation of behaviour in both vertebrates and invertebrates.

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M. G. Jancy ¹, M. Smita ², M. M. Ibrahmsha ³, O. V. Oommen ², M. A. Akbarsha ¹

Affiliations
1 Department of Animal Science, Bharathidasan Univeristy, Tiruchirappalti 620 024, IN
2 Department of Zoology, University of Kerala, Kariavattom 695 581, IN
3 Department of Zoology, Jamal Mohamed College, Tiruchirappalli 620 020, IN

Abstract

The retention of Mullerian duct in the adult male caecilians has been an intriguing aspect of reproductive biology of the vertebrates, as it defies the established knowledge of sex differentiation. It is hypothesized that this retention must have a bearing on the unique aspects of their reproduction namely internal fertilization and partial- to total viviparity, particularly in the secretion of a seminal plasma in which sperm should be suspended during ejaculation.

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R. S. Beyo ¹, O. V. Oommen ¹, M. A. Akbarsha ²

Affiliations
1 Department of Zoology, University of Kerala, Kariavattom, Thiruvananthapuram 695581, IN
2 Department of Animal Science, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620 024, IN

Abstract

This study is the first to describe the major stages of follicles of a caecilian from ultrastructural perspectives. The female reproductive system of Ichthyophis tricolor is described. Assembly of the folhcles involves the origin of primary oocytes from oogonia and the pre-granulosa cells from ovarian stroma, each from a separate nest, and the arrival of pre-granulosa cells around the meiotic oocyte to become granulosa cells. Appearance of a perivitelline space between the oocyte and the granulosa cells marks the beginning of pre-vitellogenic follicles. Macrovilli arise from the granulosa cells and ramiiy in the perivitelline space. In the vitellogenic follicles the macrovilli are further more prominent, and microvilli arising from the oolemma intercalate between the macrovilli. Yolk platelets appear in the cortical ooplasm, which are initially small and scattered but later the smaller ones fuse, and lipid and glycogen are added on resulting in large yolk platelets. The material of the vitelline envelope appears in the perivitelline space, which later condenses into the vitelline envelope. Some of the follicles undergo atresia when the granulosa cells become atrophied, and amoeboid cells from the theca enter the ooplasm and phagocytose the yolk.

Keywords

Caecilian, Follicle, Granulosa Cells, Ichthyophis tricolor, Oocyte, Ovary.

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