Fenugreek, A Potent Hypoglycaemic Herb Can Cause Central Hypothyroidism Via Leptin - A Threat To Diabetes Phytotherapy.

Fenugreek (Trigonella foenum graecum), a medicinal herb with potent antihyperglycaemic and hypoglycaemic effects, is used to treat diabetes. This study is aimed to explore the interaction of fenugreek seed extract (FSE) and HPT (hypothalamic-pituitary-thyroid) axis in context of leptin secretion which have important role in normal and type-1 diabetic subjects. FSE (confirmed to contain trigonelline, diosgenin, 4 hydroxyisoleucine) was gavaged (0.25 gm/kg body weight/day) to normal and alloxan-induced type-1 diabetic rats for 4 weeks. Expression of hypothalamic prepro-TRH (Thyrotropin releasing hormone) mRNA, serum levels of TRH, TSH (Thyroid stimulating hormone), fT3, fT4, insulin, leptin, glucose; thyroperoxidase activity and growth of thyroid gland, food intake, adiposity index were also studied FSE significantly down regulated prepro-TRH mRNA expression; decreased serum TRH, TSH, fT3, fT4 levels, and regressed thyroid gland in FSE-fed normal and diabetic rats than those observed in normal diet-fed control and diabetic rats. FSE decreased (p<0.005-0.001) adiposity index and leptin secretion, increased food intake and body weight in all FSE-fed rats. FSE improved insulin secretion, decreased glucose level but impaired HPT axis in diabetic rats, indicating insulin-independent central hypothyroidism. Results suggested that the dominant signal to hypothalamus suppressing HPT axis is the fall in leptin level which i resulted from decreased adiposity index following FSE feeding. Fenugreek simultaneously having hypoglycaemic and hypothyroidal actions raises questions whether it can be safely used to treat diabetes and/or hyperthyroidism as was suggested by many workers.

Arecoline aggravates hypothyroidism in metabolic stress in mice.

Millions of people consume betel nut for increased capacity of work. It contains arecoline which is highly toxic and has several untoward side effects on endocrine functions. In this article, the role of arecoline on thyroid function under metabolic stress was investigated in mice. Water or food-deprivation, each for 5 days, caused ultrastructural degeneration of thyro-follicular cells, evident from pycnotic nuclei, scanty rough endoplasmic reticulum and mitochondria followed by depletion of blood serum T3 and T4 levels with alteration of TSH level as compared with control. Thyroid activity was also suppressed ultrastructurally as well as at hormonal level after arecoline administration. Further, arecoline treatment in water deprivation or food deprivation stress also caused thyroid dysfunction beyond that of metabolic stress, as evident from further ultrastructural degeneration of thyrocytes and depletion of thyroid hormones in mice. The findings suggest that arecoline aggravates hypothyroid condition in metabolic stress 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.

Thyroid responses to altered photoperiod in the soft-shelled turtle Lissemys punctata punctata bonnoterre.

The aim of the current investigation was to investigate the effect of photoperiod on thyroid activity in soft-shelled turtles (Lissemys punctata punctata). Thirty days exposure of short photoperiod with 2L:22D increased relative weight, follicular epithelial height and peroxidase activity of the thyroid gland; whereas exposure of long photoperiod with 22L:2D for 30 days showed reversed changes to those of the short photoperiod in adult female turtles. These findings indicate that short photoperiod stimulates thyroid activity and long photoperiod inhibits its activity in soft-shelled turtles. It is suggested that photoperiod exerts its action on thyroid activity presumably via gonads and/or pineal-gonadal axis in 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.

Oviductal sperm storage structure and their changes during the seasonal (dissociated) reproductive cycle in the soft-shelled turtle Lissemys punctata punctata.

The oviduct of the Indian fresh water soft-shelled turtle Lissemys punctata punctata was examined throughout the year under light and scanning electron microscopes to determine the location, histomorphological characteristics, and function of sperm storage structure, as well as their changes at different phases of the seasonal reproductive cycle. Sperm storage structures in the form of tubules were observed in the wall of isthmus throughout the year. These tubules developed either by folding or fusion of the oviductal mucosal folds and were lined by both ciliated and nonciliated epithelial cells. The height and secretory activities of the epithelia were markedly high during the breeding phase (August to September) but low in the nonbreeding phase (October to June). A few short tubules lined by cuboidal epithelium appear in the wall of infundibulum only during the breeding phase. Following mating (May), inseminated sperm were stored within the tubules of isthmus up to the pre-ovulatory stage (August). Thereafter, sperm associated with PAS-positive materials secreted from the epithelium (referred to as a carrier matrix) moved forward to the infundibulum and were stored within the storage tubules of the infundibulum for a short time. Subsequently, sperm evacuated the storage tubules and entered the oviductal lumen to fertilize the subsequently ovulated eggs during or prior to ovulation. The isthmus-tubules become shorter and narrower in the regressive phase (October to November) and remained so until the early preparatory phase (April). Sperm release might have been stimulated by estrogen secreted from the ovarian follicles of pre-ovulatory turtles. Stored sperm not utilized for fertilization remained viable not less than six months in the present turtle species.

Histological and functional changes of oviductal endometrium during seasonal reproductive cycle of the soft-shelled turtle, Lissemys punctata punctata.

Scanning electron and light microscopic studies reveal significant changes in the endometrial histophysiology of the soft-shelled turtle Lissemys punctata punctata during its seasonal reproductive cycle. Scanning electron microscopy shows the entire oviductal mucosa to be only slightly folded throughout the non-breeding period (regressive, quiescent, preparatory and recrudescent phases). With the onset of the breeding phase, the mucosa shows extensive foldings and convolutions. The adluminal mucosal lining of the non-breeding oviduct is covered by a tall, dense ciliary bed, interrupted by a few fissures and pits. Microvilli-bordered secretory cells only appear amongst the ciliated cells during the breeding phase. Light microscopic study reveals the mucosal epithelium to be low pseudostratified columnar throghout the non-breeding period. The breeding epithelium, on the other hand, is tall columnar and does contain clearly distinguishable ciliated and secretory cell types. Submucosal glands only appear for a short period (ovulation to oviposition) in the infundibulum and isthmus regions of the oviduct, but these glands are observed throughout the reproductive cycle in the tube and uterus. The secretory activity of the submucosal glands, which occur only during the peak breeding stages, involves release of vesicular secretory materials through the gland openings. The stimulated endometrial histology and activity during the breeding phase coincide with increased levels of serum estrogen and progesterone, whereas the regressed and inactive state of the endometrium is paralleled by decreased levels of these ovarian steroids. © 1995 Wiley-Liss, Inc.