Enhancement of serum FSH levels after pinealectomy

The effect of pinealectomy on the circadian periodicity in serum gonadotropins was investigated in adult male rats. Pinealectomy resulted in an elevation of the serum FSH concentration 7 days after the operation. A 4-fold increase in serum FSH over 24 h with no concommitant increase in serum LH following pinealectomy suggests that the control of FSH secretion could be mediated via the pineal gland.     

Similarity between the effects of suprachiasmatic nuclei lesions and of pinealectomy on gonadotropin release in ovariectomized,sulpiride-treated and melatonin-replaced rats

The aim of this study was to compare the effects of pineal indole treatments on LH and FSH release in pinealectomized and suprachiasmatic lesioned and ovariectomized rats rendered hyperprolactinemic by acute sulpiride treatment. pinealectomy or suprachiasmatic nuclei lesions in female rats both decreased plasma LH and FHS at 10, but not at 20 d after surgery, whereas the daily afternoon administration of melatonin effectively restored levels of both gonadotropins to control values. In ovariectomized rats, pinealectomy or suprachiasmatic nuclei lesions were ineffective in counteracting the high plasma levels of LH and FSH. However, sulpiride treatment in both pinealectomized and suprachiasmatic nuclei lesioned and castrated female rats significantly decreased the levels of LH and FSH, an effect which was counteracted by daily afternoon melatonin administration. Other pineal indoles tested, i.e., 5-hydroxy- and 5-methoxytryptophol, were ineffective in regulating gonadotropin levels. The results suggest that the pineal gland, through its hormone melatonin, can modulate gonadotropin secretion by acting on a dopamine mechanism independent of hypothalamic suprachiasmatic areas.     

Proestrous gonadotropin levels in thyroparathyroidectomized female rats

Summary Intact and TPTx animals showed the expected afternoon increase in serum LH, FSH and prolactin levels. But the afternoon increase in serum LH levels in TPTx rats was less than that observed for intact animals (p<0.01). Neither serum prolactin nor FSH levels were altered by TPTx.The excellent technical and secretarial assistance ofS. Hemelt andD. Landman is gratefully acknowledged.     

Stimulation of the secretion of LH and FSH and increase in testicular weight at birth in rats]

The evolutions of serum LH and FSH concentrations and of testicular weight have been measured in the newborn Rat before, during and up to 24 hrs. after birth. A sudden and transient increase of LH and FSH is observed at birth. The testicular weight rises rapidly between 2 and 4 hrs.     

Mitotic activity in the glandular epithelium of the rat small intestine after electrothermocoagulation of the tubero-infundibular region of the hypothalamus and simultaneous resection of the pineal gland]

Radio-frequency lesions of the tubero-infundibular region of the hypothalamus and simultaneous pinealectomy are performed in rats. The double operation is followed by a significant increase of mitotic rate in the small intestine glandular epithelium. This increase is higher than the addition of the effects that are caused by each operation.     

Effects of repeated administration of potassium canrenoate (SC-14266) on serum gonadotrophin,prolactin, testosterone and progesterone in male rats

Summary Chronic administration of potassium canrenoate (SC-14266), a water-soluble anti-aldosterone agent, increased serum LH levels in male rats without altering serum levels of FSH, prolactin, testosterone and progesterone. The increase in serum LH may be due to the anti-androgenic effect of potassium canrenoate.Acknowledgments. The authors thank the Rat Pituitary Hormone Distribution Program, NIAMDD, NIH and Dr A.F. Parlow for radioimmunoassay materials.     

Comparison between serum LH and FSH levels in male and female rats during the perinatal period]

In the newborn female Rat, no transient LH and FSH serum surges were observed between 0 and 2 hrs., as compared with the newborn male. In the newborn female, a progressive increase in serum gonadotropins was observed between 2 and 6 hrs. These results indicate that, at birth, the pituitary-gonadal axis reacts in a different way in male and female Rats.     

Stimulation of pituitary LH and FSH secretion after immunoneutralization of endogenous substance P in the cycling rat]

In the cycling female Rat, administration of substance P antisera performed at noon on the proestrous day provokes a significant increase in LH and FSH serum level, right before or after the preovulatory surges, but had no effect on its occurrence or magnitude. These results suggest that substance P has a normal physiological inhibitory role in gonadotropin regulation.     

Lesions in suprachiasmatic nuclei simulate effects of pinealectomy on prolactin release in ovariectomized and sulpiride-treated female rats

Previous studies indicate that the pineal gland alters prolactin secretion, and it was suggested that at least part of the effect of the pineal hormone melatonin on prolactin release may be mediated by the hypothalamic structures. In this study, pinealectomy and lesions of the suprachiasmatic nuclei were found to alter serum levels of prolactin in the same direction, an effect that was counteracted by daily afternoon melatonin administration. Melatonin, but not other pineal indoles, also prevented sulpiride-induced prolactin secretion in pinealectomized or suprachiasmatic nuclei-lesioned and ovariectomized rats, which suggested that the pineal gland can modulate prolactin secretion by acting through a dopamine mechanism independent of hypothalamic suprachiasmatic structures.     

Neuroendocrine effects of a non-steroidal compound of testicular origin

Summary The effects of the compound (+)-1,4-diphenylbutane-2,3-diol (DPB, synthetized in the testes) on gonadotropin secretion have been studied in castrated male rats. DPB, when injected subcutaneously, does not modify serum levels of LH and FSH. On the contrary, the local implantation of DPB in the median eminence of the hypothalamus results in a significant elevation of serum FSH. It is suggested that DPB may play a physiological role in the control of FSH release.This work has been supported by grants of the Ford Foundation, New York, and of the CNR, Biology of Reproduction Program, Rome. Kits for LH and FSH radioimmunoassay have been kindly provided by the Rat Pituitary Hormone Distribution Program of the National Institutes of Arthritis, Metabolism and Digestive Diseases of the National Institutes of Health. Diphenylbutane was a kind gift of Dr R. Neher of the Ciba-Geigy Laboratories, Basel, to Dr Iturriza. Thanks are also due to Mrs Paola Assi Brunone for her skilful technical assistance.     

Radioimmunoassay of some hormones simultaneously measured in serum and breast cyst fluid

Blood and breast cyst fluid were drawn simultaneously for hormonal determination. There was no difference between serum and cyst fluid values of PRL and TSH. A significant difference was noted for LH (p less than 0.01) and FSH (p less than 0.05), serum concentrations being higher than cyst fluid concentrations.     

Monoamine oxidase activity of the hypothalamus and pituitary: alterations after pinealectomy, changes in photoperiod, or additions of melatonin in vitro.

Rat pituitary MAO activity was reduced by constant darkness and by additions of melatonin in vitro and was increased by constant light and by pinealectomy. Hypothalamic MAO activity followed the same pattern but was less dramatically affected. The data suggest that MAO may be a target enzyme for melatonin.     

Influence of pinealectomy on corticotropin (ACTH)

Sensory deprivation produced by removing the eyes and olfactory bulbs in male rats allowed pinealectomy to markedly augment the post-adrenalectomy elevation of ACTH levels. Pineal removal or sensory deprivation separately did not have this effect. Thus, intact sensory input and an intact pineal gland are independently capable of restricting the post-adrenalectomy rise in ACTH levels.     

Changes in total and polymerized tubulin of the medial basal hypothalamus and adenohypophysis of castrated or hormone-injected rats

Summary Treatment of orchidectomized rats with LH, FSH or prolactin decreased the tubulin content of the medial basal hypothalamus (MBH), whereas FSH or prolactin augmented it in the adenohypophysis (AH). After castration, negative correlations existed between serum LH and total or polymerized MBH tubulin, whereas in the AH positive correlations were found. After estradiol-progesterone treatment of spayed rats a significant correlation was found between serum LH and the percentage of AH tubulin in the polymerized form.Deceased November 24, 1979This study was supported in part by grants from the Consejo Nacional de Investigaciones Científicas y Técnicas (CON-ICET), Argentina (grant n^o 6638) and a John Simon Guggenheim Memorial Foundation Fellowship to DPC.     

Gonadostatin and gonadocrinin, polypeptides of ovarian origin with hypophysiotropic activity]

Crude acetic acid extract of Rat ovaries pretreated with pregnant mare serum (PMSG) contains native peptides with two types of separable biological activities: one, molecular weight greater than 10,000 dalton inhibits the secretion of both LH and FSH as stimulated by luteinizing hormone releasing factor (LRF) in a pituitary monolayer culture system and is referred to as gonadostatin; the other, less than 3,500 dalton, stimulates the secretion of gonadotropins and is designated as gonadocrinin. The biological activities of ovarian gonadocrinin can be competitively inhibited by an LRF-analog-antagonist, D-Phe2, D-Trp6-LRF. These ovarian peptides may participate in physiological control of pituitary LH/FSH secretion.     

Radioimmunoassay of some hormones simultaneously measured in serum and breast cyst fluid

Summary Blood and breast cyst fluid were drawn simultaneously for hormonal determination. There was no difference between serum and cyst fluid values of PRL and TSH. A significant difference was noted for LH (p<0.01) and FSH (p<0.05), serum concentrations being higher than cyst fluid concentrations.The authors are indebted to Miss J. Meister, E. Dullaert and J. Beck for their skillful technical help. We are also indebted to the National Institutes of Health, NIAMDD and the World Health Organization, International Laboratory for Biological Standards.     

Influence of light on the plasma gonadotropin concentrations in the newborn rat.

The physiological increase in plasma gonadotropin (LH and FSH) levels in newborn rats is indisputably influenced by light. Permanent illumination accentuates this increase, whereas darkness decreases it in 16-day-old female rats. In male rats of the same age, only permanent illumination was tested with the same results.     

Inhibition of hypothalamic GnRH synthesis by inhibin

Summary Both testicular and ovarian inhibin preparations blocked GnRH synthesis by the hypothalamus and consequently reduced the circulating level of FSH. The serum level of LH was unaffected.Acknowledgment. We thank Dr S. Raiti of NIAMDD, National Institutes of Health, Bethesda, USA, for rat-hormone assay kits and Ms Maria Enrica Mongardi of Instituto Farmacologico Serono, Italy, for GnRH RIA kit.     

Effect of testosterone on the hypothalamic-pituitary-gonadal axis of pinealectomized and pineal-intact male rats.

Previous studies indicate that steroid hormones alter pineal biochemistry, and it has been suggested that at least part of the negative feedback effect of steroid hormones on pituitary gonadotropin release may be mediated by the pineal gland. In this study, pinealectomy did not alter the inhibitory effect of testosterone on neuroendocine-gonadal activity in the male rat, suggesting that the pineal gland does not mediate the response of the rat hypothalamic-pituitary axis to testosterone.     

The effect of gonadotrophins on the steroidogenesis, in the ovary and testis of gonadotrophin-deprived fresh water teleost, Cyprinus carpio.

Studies have been made on the effect of LH, FSH, and LH+FSH on the gonadal steroidogenesis in gonadotrophin-deprived common carp. LH alone and in combination with FSH was more effective than FSH in stimulation of steroidogenesis.