Reproductive Hormonal Axis of the Male Rat in Experimental Hypothyroidism

Kalland, Gene A.; Vera, Arnoldo; Peterson, Margaret; Swerdloff, Ronald S.

doi:10.1210/endo-102-2-476

Cited by 52 publications

(23 citation statements)

References 17 publications

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“…Boutrand et al [10] showed that plasma LH response after intravenous injec tion of GnRH was higher in Tx rats than in normal rats. Also, injection of GnRH caused a significantly greater increase of serum LH in hypothyroid than in euthyroid rats [11,12], These in vivo observations are in agreement with the data of our present in vitro studies, and reflect a possibility of the increase in the number and/or in the binding affinity of GnRH receptors in Ovx rat AP following thyroidectomy. Some evidence in dicates that the binding of GnRH to AP var ied within the estrous cycle [13] and is af fected by sex steroids [14], Castration pro duced an increase in the number of GnRH receptors, and treatment with steroid hor mones decreased or prevented the rise of pituitary GnRH receptors [15,16].…”

Section: Discussionsupporting

confidence: 88%

Effects of Thyroidectomy and Thyroxine Replacement on the Release of Luteinizing Hormone and Gonadotropin-Releasing Hormone in vitro

Wang¹,

Pu²,

Chiang³

et al. 1987

Horm Res

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The effects of thyroidectomy and thyroxine (T4) replacement on the release of luteinizing hormone (LH) and gonadotropin-releasing hormone (GnRH) in ovariectomized (Ovx) rats were studied. Immediately after ovariectomy, rats were thyroidectomized (Tx) or sham-Tx. The Ovx-Tx rats were injected subcutaneously with either saline or T4 (2 µg/100 g body weight) daily for 30 days before sacrifice. Sham-Tx rats were treated with saline only. Twenty hours after the last injection, the blood sample was obtained by decapitation. The excised anterior pituitary gland (AP) was bisected and incubated in vitro with or without 0.1 0.5, 2.5, and 50 ng GnRH at 37 °C for 4 h. The mediobasal hypothalamus (MBH) was bisected and incubated with or without the AP of Ovx donor rat in vitro. Concentrations of LH and GnRH in the medium and that of LH in the serum were measured by radioimmunoassay. LH in the serum of Tx rats was higher than that in the serum of sham-Tx and Tx-T4 rats. Thyroidectomy resulted in an increase of LH release by Ovx rat AP, stimulated with or without 0.1 and 50 ng GnRH, as well as in an increase of immunoreactive GnRH release from MBH of Ovx rats in vitro. After a 4-hour incubation with donor APs, the LH in the medium containing MBH obtained from Tx rats was significantly higher than that obtained from sham-Tx and Tx-T4 rats. LH concentrations, in both sera and media, as well as GnRH concentration in the media of euthyroid and T4-replaced Tx groups were nonsignificantly different. These results suggest that T4 is inhibitory to the basal and GnRH-stimulated LH release as well as to the release of GnRH in the absence of ovarian hormones.

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Section: Discussionsupporting

confidence: 88%

Effects of Thyroidectomy and Thyroxine Replacement on the Release of Luteinizing Hormone and Gonadotropin-Releasing Hormone in vitro

Wang¹,

Pu²,

Chiang³

et al. 1987

Horm Res

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“…The increased level of E2 may be due to increased peripheral metabolism of androgens into estrogen [90]. Kalland et al [48] and Cristovao et al [32] found no change in serum testosterone in prepubertal and adult hypothyroid rats, but 376 R. R. M. Maran most reports showed serum T and E2 levels to be low in hypothyroid rats and rams, while an opposite effect was observed in hyperthyroid animals [15, 24-26, 35, 63, 67, 68, 85, 98]. Recently, we reported that low levels of T, DHT, and E2 were found in the plasma and testicular interstitial fluid (TIF) of hypothyroid rats whose hypothyroidism was induced neonatally [68].…”

Section: Serum Sex Steroids Under Altered Thyroid Statusmentioning

confidence: 99%

Thyroid Hormones: Their Role in Testicular Steroidogenesis

Maran

2003

Archives of Andrology

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“…Photomicrographs of sections of ovary of control and melatonin treated hypothyroid rats. Sections of ovaries of 2 245 and 90 day old rats (1,3,5) showing less number of atretic follicles and number of primary, secondary and tertiary follicles compared to age matched melatonin treated hypothyroid rats (2,4,6). significantly lower than the control level at 45 and 90 days.…”

Section: Serum Hormone Profilementioning

confidence: 82%

“…Thyroid hormones are critically involved in embryonic and foetal development of vertebrates [2]. Both thyroid hormone deficiency and excess are known to affect the development and functions of reproductive system [3,4]. Prepubertal hypothyroidism induced from the day of birth till day 40 postpartum shows reduced body and ovarian weights, with the ovaries of such rats containing more secondary and less antral follicles, smaller non-atretic antral follicles and more atretic follicles with no corpora lutea compared to age-matched controls [5].…”

Section: Introductionmentioning

confidence: 99%

Simultaneous Melatonin Administration Effectively Deprograms the Negative Influence of Neonatal Hypothyroidism on Immature Follicles but not on Mature Follicles and Body and Ovarian Weights

Thakkar

2011

J Endocrinol Metab

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Background: The impact of simultaneous melatonin administration on neonatal progmming by hypothyroidism (HPOT + MT) on adult ovarian functions and serum hormone profiles has been evaluated in the Charles foster strain of rats. Methods:The female neonates were rendered hypothyroid (HPOT) by feeding lactating mothers with 6-propyl 2-thiouracil (PTU) through drinking water and were simultaneously administered with melatonin (MT) (40 µg/animal/day) from day 0 to day 21 in the evening at 16:30 hours just prior to lights off. Results:The experimental animals (HPOT + MT) consistently showed decreased body and ovary weights compared to controls. The total number of follicles was significantly lower in treated animals (HPOT + MT) but was greater than the HPOT group of animals, and both showed significantly decreased number of follicles compared to control rats. There was a significant reduction in the number of antral follicles and corpora lutea and decreased atretic follicles in experimental rats. Conclusions:It can be concluded from the above results that melatonin is able to nullify the negative influence of hypothyroidism on adult ovarian functions and steroidogenesis to a greater extent.

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Reproductive Hormonal Axis of the Male Rat in Experimental Hypothyroidism

Cited by 52 publications

References 17 publications

Effects of Thyroidectomy and Thyroxine Replacement on the Release of Luteinizing Hormone and Gonadotropin-Releasing Hormone in vitro

Effects of Thyroidectomy and Thyroxine Replacement on the Release of Luteinizing Hormone and Gonadotropin-Releasing Hormone in vitro

Thyroid Hormones: Their Role in Testicular Steroidogenesis

Simultaneous Melatonin Administration Effectively Deprograms the Negative Influence of Neonatal Hypothyroidism on Immature Follicles but not on Mature Follicles and Body and Ovarian Weights

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