Arecoline plays dual role on adrenal function and glucose-glycogen homeostasis under thermal stress in mice.

Arecoline has biomedical importance, but it has untoward side effects on endocrine functions. The aim is to investigate its role on adrenal activity under thermal stress by ultrastructural and hormonal parameters in mice. Cold (4 °C) or heat (37 °C) stress, or arecoline (10 mg/kg body wt), each for 7 days in cold or heat stress stimulated adrenocortical activity ultrastructurally with an elevation of corticosterone level. Adrenomedullary activity was suppressed in cold stress with depletion of catecholamine levels. In heat stress, adrenomedullary activity was stimulated ultrastructurally with an elevation of catecholamine levels. Arecoline treatment alone, or in cold or heat stress suppressed adrenomedullary activity, judged by ultrastructural and hormonal parameters. Arecoline treatment caused hypoglycemia with an elevation of glycogen level, but cold or heat stress, or arecoline treatment in thermal stress caused hyperglycemia, with a fall in glycogen profile. Thus, arecoline in thermal stress plays a dual role on adrenal function and glucose-glycogen homeostasis in mice.

Arecoline ameliorates hyperthyroid condition in mice under cold stress.

Betel nut of Areca catechu is chewed by millions of people for increased capacity to work and stress reduction, but it contains arecoline that causes hypothyroidism. The aim is to investigate the role of arecoline on thyroid activity in cold stress in mice. Arecoline treatment (10 mg/kg body wt/day, for 7 d) caused a reduction in thyroid weight and ultrastructural degeneration of thyro-follicular cells with depletion of T3 and T4 levels compared with the control mice. Cold stress (4 °C for 2 h, twice daily, for 7 d) stimulated thyroid activity ultrastructurally with an elevation of T3 and T4 levels. Arecoline treatment in cold stress suppressed thyroid activity by showing reversed changes to those of cold stress. In contrast, TSH concentrations were consistently increased under all experimental conditions. The findings suggest that cold stress causes hyperthyroidism which arecoline can ameliorate in mice.

Adrenomedullary and glycemic alterations following diverse stress in soft-shelled turtles Lissemys punctata punctata Bonnoterre.

The objective of the current investigation was to study adrenomedullary and glycemic responses to stress in soft-shelled turtles, Lissemys p. punctata. Dehydration (7 days) and formalin (formaldehyde 1%, 0.1 mL/100 g body wt. daily for 7 days) stress-stimulated adrenomedullary activity at histological (by increasing the nuclear diameter and degranulation of chromaffin cells) and hormonal levels (by elevations of norepinephrine and epinephrine concentrations) with hyperglycemia in turtles. But salt loading (NaCl: 1%, 1 mL/100 g body wt. daily for 7 days) had no significant effect on adrenomedullary activity or glycemia presumably owing to the nonresponsiveness of adrenocortical activity to salt stress in turtles. It is suggested that dehydration and formalin stresses might have exerted their actions through the hypothalamo (CRF)-hypophysial (ACTH)-adrenocortical axis in turtles.

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.

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

The effects of some exogenous peripheral hormones (thyroxine, corticosterone, epinephrine, norepinephrine and insulin) on thyroid activity were investigated in juvenile female soft-shelled turtles, Lissemys punctata punctata. Each hormone was injected in three different doses (25 microg, 50 microg or 100 microg each per 100 g body weight, once daily at 9 AM) for 10 consecutive days. Thyroid activity was evaluated by gravimetry, histology (epithelial height) and thyroperoxidase assay. The findings revealed that thyroxine in low dose (25 microg) stimulated thyroid activity by increasing the relative thyroid weight, epithelial height and thyroperoxidase activity, but inhibited gland activity at a high dose (100 microg) by decreasing the values of all these parameters. The medium dose (50 microg) had no significant effect. All other hormones, in all doses, significantly decreased thyroid activity by decreasing the values of all the parameters. Thyroid responses to exogenous hormones are generally dose-dependent in turtles. The mechanisms of actions of the hormones administered are suggested.

Adrenocortical involvement during diverse stress in soft-shelled turtle Lissemys p. punctata Bonnoterre.

Adrenocortical responses to diverse stressful situations (dehydration, formaldehyde treatment and salt loading) were studied in the adult female soft-shelled turtle, Lissenmys p. punctata. Dehydration, formaldehyde treatment (formalin, 1%: 0.1 ml/100 g body weight daily) or salt loading (NaCl, 1%: 0.1 ml/100 g body weight daily) treatments consecutively for 7 days caused hypertrophy of the adrenocortical cells with their nuclear diameter increased, and depletions of adrenal cholesterol and ascorbic acid concentrations followed by decreased acid phosphatase and alkaline phosphatase activities in turtles. Corticosterone levels were elevated in both the adrenal gland and serum of turtles after dehydration and formalin stress, but the hormone level remained unaltered after salt loading in turtles. The results suggest active involvement of adrenal cortex in stress for homeostasis in Lissemys turtles.

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.

Interrenal responses to high ambient temperature in soft-shelled turtle, Lissemys punctata punctata.

An exposure to ambient temperature of 25 degrees C had no perceptible effect on interrenal function but further increase of temperature to 35 degrees C caused nuclear hypertrophy with increase of nuclear diameter, RNA concentration, acid phosphatase and alkaline phosphatase activities, accompanied by quantitative depletions of cholesterol (free, esterified and total) and ascorbic acid levels in the interrenal gland of the soft-shelled turtle Lissemys p. punctata. Similar manifestations of stimulation, except in the nucleus, were marked after exposure to 38 degrees C, but the degree of response in respect of esterified and free cholesterol levels was higher at 38 degrees C than at 35 degrees C. Moreover, withdrawal of 38 degrees C temperature and subsequently maintaining at 25 degrees C for 15 days showed reverse manifestations to those of 35 degrees C/38 degrees C, leading to a tendency towards normalcy. It is suggested that high a ambient temperature of 35 degrees C significantly stimulates interrenal function of Lissemys turtles, but further increase of 38 degrees C does not cause further overall stimulation, and withdrawal of higher temperature (38 degrees C) shows a tendency towards normalcy. It is also suggested that (a) high ambient temperature causes thermal stress, (b) it is reversible and (c) it acts on interrenal activity presumably via CRF-ACTH-axis in turtles.

Adrenomedullary hormonal and glycemic modulation following gonadotropin and sex hormone administration in the soft-shelled turtle Lissemys punctata punctata.

The aim of the current investigation was to ascertain whether gonadotropins and sex hormones can modulate adrenomedullary and glycemic functions in turtles. Exogenous FSH (3.0 microg/100 gm body wt daily for 10 days) stimulated adrenomedullary activity by increasing nuclear diameter and cytoplasmic degranulation, and elevating adrenal norepinephrine and epinephrine, and blood glycemic levels in turtles. LH (3.0 microg/100 gm body wt daily for 10 days) had no significant effect and the combined treatment of FSH and LH (3.0 microg each/100 gm body wt daily for 10 days) failed to show further adrenomedullary stimulation and hyperglycemia beyond that of FSH alone. Estrogen treatment in low dose (25 microg/100 gm body wt daily for 10 days) had no significant effect on adrenomedullary activity or glycemia, but at higher doses (50 microg or 100 microg/100 gm body wt daily for 10 days) showed dose-dependent adrenomedullary stimulation by inducing the same manifestations as those of FSH. Progesterone in low dose (25 microg/100 gm body wt daily for 10 days) had no perceptible effect, but in other doses (50 microg/100 microg per 100 gm body wt daily for 10 days), suppressed dose-dependent adrenomedullary activity by reversing the changes to those of estrogen. Simultaneous treatment with estrogen and progesterone (50 microg each/100 gm body wt daily for 10 days) failed to show further changes beyond that of estrogen alone.