The relationship between pineal and thyroid in response to the adrenocortical modulation is poorly understood. In the present study post pubertal male rats were treated with natural and synthetic corticoids and an antiadrenal agent mitotane. Hydroxycortisone was administered at a dose of 4 mg / 100 g b.w., dexamethasone 2 mg / 100 g b.w. and mitotane 3 mg / 100 g b.w. for fifteen consecutive days. Our data revealed that both the corticoids, hydroxycorticosterone and dexamethasone induced hyperactivity of pineal and thyrofollicular cell morphology. The functional relation between the cells of the pineal parenchyma and thyroid follicles were noted. Similar results were induced by mitotane, an antiadrenal agent. It is concluded, that our present study indicates a mutual relationship between the pineal and the thyroid gland karyomorphological and functional parameters in response to corticoids and an antiadrenal agent in post pubertal male rat (Rattus rattus).

Stimulatory response of pineal-thyroid nuclear morphology and function following adrenocortical modulation in rat (Rattus rattus)

Noise is a world-wide problem that causes nervous, endocrine and cardiovascular disorders, and eventually health hazards in humans and animals. Objective of the current work is to investigate endocrine interaction in noise stress, which subsequently affects other endocrine functions including gonads in a poultry bird like chicks. Gravimetric, ultrastructural and hormonal status of the endocrine organs were examined to ascertain the effects of noise stress. Acute noise at 60 dB had no effect, but at 80 and 100 dB each for 3 h, increased pineal and serum serotonin, and adrenal and serum corticosterone, epinephrine and norepinephrine concentrations, without any change in thyroid or gonadal hormones. Chronic noise exposure at 60, 80 and 100 dB each for 6 h, daily for 7 days, drastically disturbed normal behavior, and quantum of food consumption and water intake. Chronic exposure also significantly decreased body weight including thyroid, ovary and testis weight, and increased adrenal weight. Noise stress caused ultrastructural changes leading to stimulations of pinealocytes (with abundance of rough endoplasmic reticulum and mitochondria), adrenocortical cells (enlarged nuclei and abundance of smooth endoplasmic reticulum) and adrenomedullary cells (enlarged nuclei with presence of chromaffin granules) were observed in noise stress. Additionally, pineal and serum serotonin, N-acetyl serotonin and melatonin, and adrenal and serum corticosterone, epinephrine and norepinephrine levels were significantly elevated following chronic noise exposure. Contrarily, thyroid activity was suppressed with atrophied thyroid follicles followed by declined levels of serum T3 and T4 with elevation of TSH level. Simultaneously, serum 17β-estradiol (E2) and testosterone (T) concentrations were also significantly declined in all the doses of chronic noise. These changes were dose dependent of noise exposure. The findings suggest that (a) adrenal and pineal glands respond primarily to noise and secondarily act on other endocrine organs including gonads in chicks, (b) adrenal directly and/or indirectly causes thyroid and gonadal dysfunctions via pineal following noise exposure in chicks.

Noise Induces Hypothyroidism and Gonadal Dysfunction Via Stimulation of Pineal–Adrenal Axis in Chicks

A composite study including pineal and thyroid cell morphology, hormonal analysis and function in response to exogenous melatonin administration awaits in depth investigation in any bird. To investigate the pineal and thyroid responsiveness to exogenous melatonin from combined morphological and hormonal studies in neonatal chicks – two groups, each with eleven chicks were used as control (C) and treated with melatonin (M) at a dose of 100 µg.100 g body weight for fifteen consecutive days. The treatment with melatonin induced stimulation of pineal karyomorphology as evidenced from significantly increased nuclear diameter in the melatonin treated group. On the contrary, melatonin used inhibition of thyroidal activity as evidenced by significantly decreased values of thyroid nuclear diameter, thyrofollicular epithelial height, diameter and D/N activity associated with significantly decreased T4 values in neonatal male chicks. Our study thus shows that exogenous melatonin induced disparate changes in pineal and thyroid gland activity in these neonatal chicks, whereas pineal gland showed an overall stimulation; in contrast, melatonin induced thorough inhibition of thyroid cytophysiomorphology and hormonal milieu compared to control group of neonatal chick (Gallus domesticus)

Exogenous melatonin induced disparate changes in pineal karyomorphology and thyroid cytophysiology and T 4 levels in chick (Gallus domesticus)

The purpose of this investigation was to explore whether the pineal organ and its hormone melatonin has any influence on the activity of thyroid glands, if so, how that relates to the reproductive status of a hitherto unstudied seasonally breeding wild bird. Accordingly, an identical experimental regimen was followed with adult male spotted munia (Lonchura punctulata; Passeriformes) during both its gametogenically active (August-September) and inactive (March-April) phases of the annual reproductive cycle. In either case, the levels of circulating thyroid hormones (both T3 and T4) and cellular characteristics of thyroid glands in groups of birds were studied following surgical removal of the pineal gland and/or daily afternoon administration of melatonin (10 μg/ 100 g body weight/ day for 30 days). The results of the same experimental schedule were found to be different depending on the sexual status of the concerned birds. During the breeding phase, pinealectomy (Px) induced significantly decreased value...

Effects of Pinealectomy and Exogenous Melatonin on the Thyroid Gland Activity Varies in Relation to Reproductive Status of Male Spotted Munia (Lonchura punctulata; Aves, Passeriformes)

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 The current investigation was undertaken to asses the pineal and thyroid gland cytophysiology and function in response to exogenously altered steroid milieu following administration of steroid hormone and non-steroidal antihormones. In the present study male rat ( Rattus rattus ) were injected with estradiol at a dose of 2 mg, testosterone 100 µg, tamoxifen 100 µg and flutamide 2 mg per 100 g. b.w. in all cases and injected intramuscularly for 15 consecutive days. Control rats were similarly injected with peanut oil vehicle intramuscularly for same duration as those of treated groups. The results indicated that pineal and thyroid gland response to estradiol and testosterone administration was opposite in nature, whereas estradiol induced significant hypertrophy of pineal and thyroid cytophysiology as indexed from significant increased pineal and thyroid karyomorphological and associated parameter values, testosterone on the reverse caused significant atrophy of pineal and thyroid cytophysiological parameters. Tamoxifen acted as a true estrogen agonist whereas flutamide showed androgen antagonist nature thereby causing hyperactivity of pineal and thyroid karyomorphological and associated functions similar to that observed in estradiol treated rats opposite to that shown by testosterone induction in these rats.

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Pineal-Thyroid Cytophysiological Responsiveness to Altered Steroid Hormone and Antihormone Milieu in Rat (Rattus rattus)

Melatonin induced morphology of the thyrofollicular activity in Blossomheaded parakeets (Psittacula cyanocephala) and Indian weaver birds (Ploceus philippinus)

A Sarkar

Papers

Melatonin induced morphology of the thyrofollicular activity in Blossomheaded parakeets (Psittacula cyanocephala) and Indian weaver birds (Ploceus philippinus)