Seema Rai

Pineal oscillator functioning in the chicken – Effect of photoperiod and melatonin

The avian pineal gland, apart from the hypothalamic master clock (suprachiasmatic nuclei, SCN) and retina, functions as an independent circadian oscillator, receiving external photic cues that it translates into the rhythmical synthesis of melatonin, a biochemical signal of darkness. Functional similarity to the mammalian SCN makes the avian pineal gland a convenient model for studies on biological clock mechanisms in general. Pineal melatonin is produced not only in a light-dependent manner but also remains under the control of the endogenous oscillator, while the possible involvement of melatonin in maintaining cyclic expression of the avian clock genes remains to be elucidated. The aim of the present study was to characterize the diurnal profiles of main clock genes transcription in the pineal glands of chickens exposed to continuous light (LL) and supplemented with exogenous melatonin. We hypothesized that rearing chickens from the day of hatch under LL conditions would evoke a functional pinealectomy, influencing, in turn, pineal clock function. To verify this hypothesis, we examined the diurnal transcriptional profiles of selected clock genes as well as the essential parameters of pineal gland function: transcription of the genes encoding arylalkylamine N-acetyltransferase (Aanat), a key enzyme in melatonin biosynthesis, and the melatonin receptor (Mel1c), along with the blood melatonin level. Chickens hatched in summer or winter were maintained under LD 16:8 and 8:16, corresponding to the respective photoperiods, as the seasonal control groups. Another set of chickens was kept in parallel under LL conditions and some were supplemented with melatonin to check the ability of exogenous hormone to antagonize the effects evoked by continuous light. Twelve-day-old chickens were sacrificed every 3 h over a 24-h period and the mRNAs of selected clock genes, Bmal1, Cry1, Per3, E4bp4, together with those of Aanat and Mel1c, were quantified in the isolated pineal glands. Our results indicate that the profiles of clock gene transcription are not dependent on the duration of the light phase, while LL conditions decrease the amplitude of diurnal changes, but do not abolish them entirely. Melatonin supplied in drinking water to the birds kept in LL seems to desynchronize transcription of the majority of clock genes in the summer, while in the winter, it restores the pattern, but not the diurnal rhythmicity. Rhythmic expression of Bmal1 appears to provide a direct link between the circadian clock and the melatonin output pathway, while the availability of cyclic melatonin is clearly involved in the canonical transcription pattern of Per3 in the chicken pineal gland. Regardless of the experimental conditions, a negative correlation was identified between the transcription of genes involved in melatonin biosynthesis (Aanat) and melatonin signal perception (Mel1c receptor).

Melatonin vs. phytomelatonin: Therapeutic uses with special reference to polycystic ovarian syndrome (PCOS)

Abstract Melatonin—a tiny tryptophan derivative in the bovine pineal extract. Since then, this wonder molecule is known to regulate a wide variety of physiological and psychological activities of lower and higher vertebrates including the human beings. The exact mechanisms of melatonin actions are poorly understood and explained to date, but the coexistence of endocrine, paracrine, autocrine, and intracrine actions and feedback effects are suggested mostly to be mediated by the specific receptors found in the respective target organs. Melatonin exhibits a remarkable contextual diversity of functions as circadian pacemakers, hypothalamic/pituitary axes to vasomotor effects, immunomodulatory, antioxidative actions, anti-apoptotic effects (direct and indirect), etc. Melatonin with such efficacy and safety may therefore eventually drive its use with other plant extracts containing phytomelatonin in universally effective clinical applications and an adjuvant therapy specially during Polycystic Ovarian Syndrome (PCOS) for treatment in near future and can be proved as a best medicinal tool.

Melatonin Attenuates Free Radical Load and Reverses Histologic Architect and Hormone Profile Alteration in Female Rat: An In vivo Study of Pathogenesis of Letrozole Induced Poly Cystic Ovary

Objectives: The present study was designed and conducted for obtaining information about the role of melatonin (Mel) in pathophysiology of polycystic cystic ovarian syndrome (PCOS) which generally leads to infertility in human females.Methodology: Letrozole, a non-steroidal aromatase inhibitor supplemented (1 mg/100 g/body weight/day for 28 days) for induction of (PCOS). Treatment of exogenous melatonin (200 μg/100 g/body weight/day) was given to PCO and normal rats. After completion of experiment gravimetric analysis, Lipid peroxidation (LPO) in terms of thiobarbituric acid reactive substance (TBARS), histological slide preparation following hemotoxylene-eosin (HE) double staining method for ovarian tissue was done and results were documented. Hormonal assay estrogen (E), progesterone (P), and Melatonin (Mel), luteinizing hormone (LH) and follicle stimulating hormone (FSH) was performed using ELISA kit.Major findings: Letrozole induced PCOS exhibited increase in ovarian weight, lipid peroxidation level (LPO). Histopathology of PCO rats showed sub-capsicular cysts and capsicular thickening. Circulatory hormone profiles showed a significant decrease in plasma level of E, P, Mel. Plasma testosterone (T) level was noted significantly high whiles an unsteady ratio of LH) and FSH in PCOS rats. Melatonin treatment to the PCO rats showed recovery in ovarian weight, significant decrease in lipid per oxidation (LPO), withdrawal of presence of cyst from ovarian histology, reversal of plasma circulatory hormone profile to the control group of rats.Conclusion: The finding update about similarity of ovarian cysts in rats to that observed in human PCOS and their regression following exogenously melatonin administration. The present findings may indicate and novel therapeutic approach based on the modulation of pathogenicity of PCOS in female rats through melatonin to improve the functional ovarian physiology as a possible future molecule among human females to treat the infertility. Such clinical trials may really prove to be highly beneficial for women with PCOS.

Receptor Cross Talk and Interplay between Melatonin and Ovarian Thyroid Axis in a Letrozole Induced Polycystic (Pco) Rat

The objective of present study was to establish the interrelationship between thyroid and melatonin during anovulatory/letrozole induced polycystic ovarian condition on female Wister rats. Rats were procured and after acclimatization 20 rats were divided in 4 groups with 5 rats in each. They were divided as Control, Letrozole induced PCO rat (1 mg/kg BW/d), and melatonin alone (200 μg/100 g BW/d). The experiment was conducted for the duration of 28 d. Assessment of gravimetric, hormonal profile and thyroid histology and relative expression of MT1, MT2, and ERα, (thyroid, ovary) Dio2, TRα (Ovary) done followed by standard protocol. Histological observation showed shrinkages in thyroid follicles in PCO rats however exogenous melatonin maintained the cellular architecture and normal thyroid weight. PCO rats showed significantly high circulating testosterone but significant decreased in estrogen and progesterone level. Circulatory gonadotropins (LH, FSH) were noted significantly high in PCO rats. Melatonin injection to the PCO rats however reversed to the control level and restored. Circulatory TSH level in PCO rats were noted suppressed where as T3 and T4 were non-significantly increased suggesting a reciprocal relation between melatonin and thyroxine. Thyroid tissue of PCO rats expressed MT1 and MT2 in way alternate and opposite way being MT1 as up regulated whereas down regulation of MT2. Ovarian tissue of PCO rats showed reverse receptor expression to that of thyroid tissue being MT1 down regulated and MT2 was noted unregulated. Parallel relation was noted between ERα and TRα receptor expression in thyroid and ovarian tissue respectively. PCO rats resulted in up regulation of Dio2, receptor expression in a non-significant manner. Therefore, present finding suggests a fine interplay and cross talk via melatonin its two receptor MT1 , MT2 with ERα, TRα, and Dio2 thyroid and ovarian tissue as the case between ovarian thyroid axis hence maintaining a physiological trade-offs between theses gland with a tonic regulation to maintain melatonin and thyroid homeostasis during polycystic pathogenicity.

Phytochemical Characterization and Antioxidative Property of Ocimum canum : Effect of Ethanolic Extract of Leaves and Seeds on Basic Immunologic and Metabolic Status of Male Rats

The present study was carried out to assess the effect of ethanolic extract of leaves and seeds of Ocimum canum on the hematological parameters (hemoglobin percentage (Hb%), Red Blood Corpuscles (RBC), White Blood Corpuscles (WBC), Differential Leukocyte Counting (DLC)), free radical load on vital organs (brain, testis, liver and kidney) and lymphoid organs (bone marrow, spleen) of male rat. Chemical characterization of leaves and seeds of O. canum showed the presence of volatile oils, flavonoids, carbohydrates, phytosterols, tannins and fixed oils. An oral dose of extracted leave and seeds with 0.05mg/100g body weight daily was given to the rats for 30 days. The hematological parameter showed significant (*p<0.05) increase in Hb%, R.B.C. and basophil was noted. Whereas a significant decrease in the monocyte and eosinolphil was found after the supplementation by ethanolic extract of leaves and seeds and therefore the impact may be said as cell specific. Supplementation of the extract of leave and seeds resulted in the significant decrease of free radical load expressed in Thiobarbituric acid reactive substances (TBARS) in brain. However leaves extract was noted more effective in case of liver, kidney and testis in lowering the free radical load.

Biochemical and Histopathological Inflections in Hepato-renal Tissues ofStreptozotocin (STZ) Induced Diabetic Male Rats: Impact of Exogenous Melatonin Administration

Objective: To evaluate the therapeutic efficacy of exogenous melatonin (MEL) on hepato-renal tissue in a diabetic rat model. Methodology: Streptozotocin (STZ) was used to establish diabetic rat model. Diabetes was confirmed by monitoring the blood glucose level, animals having glucose level above 250 mg/dl were considered as diabetic and were divided into six different groups. Model control group, diabetic group, melatonin treatment to diabetic rats, melatonin per se group, glibenclamide (a standard hypoglycemic drug) treatment to diabetic rats and glibenclamide (standard control) alone respectively. The model control was given 0.5 ml (0.1 M) citrate buffer, experiment was conducted for one month. After the completion of experiment, rats were sacrificed. Blood was collected and centrifuged at 3000 rpm for 10 minutes to obtain the serum. Serum was kept at -800c for further analysis of liver and renal function tests and lipid profile. Liver and kidney tissues were weighed, fixed in Bouin’s fixative for histopathological studies. Further tissues were processed for Lipid peroxidation (LPO), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT). Major findings: Administration of MEL to STZ induced diabetic rat showed a significant decrease of lipid peroxidation (TBARS) in kidney and liver tissue comparable to the control and GLIBEN group of rats. In addition MEL prevented the decrease in antioxidative enzyme parameters viz. superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) of hepato-renal tissues. Parameters of liver functions (alanine amino transaminase (ALT), aspartate amino transaminase (AST) and alkaline phosphatase (ALP) and renal function (urea, uric acid and creatinine) were noted restored following MEL treatment. MEL administration further maintained the normal levels of lipid profiles i.e., triglyceride, cholesterol, low and high density lipoprotein (LDL, HDL) to that of the control group of rats. Histological architecture of liver and kidney tissues were noted repaired and rescued as judged by cellularity of hepatocytes and renal cells. Conclusion: The present finding strongly indicates the protective effect of exogenous melatonin for hepato-renal tissues form the damages and impairment observed and noted in the experimentally induced STZ male rat model.

Immunophysiological Significance for Differential Receptor Expression of Melatonin (Mel1aR/Mel1bR), Cytokine(s) (IL-2R/IL-10R/TGF-òR) and Tyrosine Hydroxylase (THR) in Lymphocyte Sub-Population: A Novel Crosstalk between Melatonin and Catecholamines

Retraction Note The article entitled “Immunophysiological Significance for Differential Receptor Expression of Melatonin (Mel1aR/Mel1bR), Cytokine(s) (IL-2R/IL-10R/TGF-β R) and Tyrosine Hydroxylase (THR) in Lymphocyte Sub-Population: A Novel Crosstalk between Melatonin and Catecholamines” has been accepted for publication in the Journal of Clinical and Cellular Immunology. Soon after publication of the paper in the Volume 6 Issue 4, the authors of the paper would like to retract the paper for their personal reasons. Therefore, the journal publisher disowns the paper from the issue 4 of volume 6. Hereafter the content of the paper may not available online in any of the publisher’s websites or related weblinks