Regulation of the preovulatory gonadotropin surge by endogenous steroids

Estradiol secreted by growing ovarian follicle(s) has been considered classically to be the neural trigger for the preovulatory surge of gonadotropins. The observation that the estradiol-induced gonadotropin surge in ovariectomized rats is of lesser magnitude and duration than that found in the cycling rat at proestrus has resulted in a search for other steroid regulators. Progesterone is a major regulator of the preovulatory gonadotropin surge. It can only act in the presence of an estrogen background, which is necessary for the synthesis of progesterone receptors. In the estrogen-primed ovariectomized rat, progesterone is able to initiate and enhance the gonadotropin surge to the magnitude observed on the day of proestrus and limit it to 1 day. The physiological role of progresterone in the induction of the preovulatory gonadotropin surge has been demonstrated by the attenuation of the progesterone-induced surge and the endogenous proestrus surge by progesterone receptor antagonist RU486 and the progesterone synthesis inhibitor trilostane. The promoter region of the follicle-stimulating hormone (FHS)-beta gene contains multiple progesterone response elements and progesterone brings about FSH release as well. The reduction of progesterone in the 5 alpha-position appears to be important for the regulation of progesterone secretion. Corticosteroids appear to play a significant role in the secondary FSH surge on late proestrus and early estrus.     

Evidence for a luteinizing hormone surge center in the hypothalamus of the pig

Lipoprotein-X (Lp-X) is an abnormal low-density lipoprotein frequently found in liver disease. It is regarded as the most sensitive and specific biochemical parameter for the diagnosis of intra- and extrahepatic cholestasis. Moreover, Lp-X is supposed to contribute to the development of hypercholesterolemia in cholestatic liver disease, because it fails to inhibit de novo cholesterol synthesis. This investigation will focus on the relationship between the presence of Lp-X and serum lipid concentrations in cirrhosis. The significance of Lp-X in the diagnosis of cholestasis, compared with alkaline phosphatase (AP), gamma-glutamyl transferase (GGT), and bilirubin levels, will be assessed as well. The present cross-sectional study includes 212 patients with histopathologically proven cirrhosis. The detection of Lp-X and the quantification of -, beta-, and pre-beta-cholesterol was based on agar gel electrophoresis and polyanion precipitation. For the characterization of liver function, the concentrations of albumin and bilirubin, the activities of liver enzymes, and coagulation times were assessed. In a subgroup of 40 individuals, liver biopsies were re-evaluated to confirm or exclude intrahepatic cholestasis. As a result, there was no association between the appearance of Lp-X and total cholesterol concentrations. While all patients with Lp-X showed intrahepatic cholestasis (predictive value of the positive test = 1), only 16 of 28 patients with cholestasis formed Lp-X (sensitivity = 0.57). The activities of AP and of GGT, as well as the concentrations of bilirubin, were strongly elevated in most patients, with and without cholestasis. The predictive values of AP, GGT, and bilirubin were 0.77, 0.69, and 0.74 for the positive test and 0.5, 0, and 0.6 for the negative test, respectively. We conclude that Lp-X is not related to hypercholesterolemia in cirrhosis. The positive, but not the negative, Lp-X test has high predictive value for the diagnosis of cholestasis in cirrhosis. The biochemical parameters traditionally used for the assessment of extrahepatic cholestasis, AP, GGT, and bilirubin, do not support the diagnosis of intrahepatic cholestasis caused by cirrhosis.     

Importance of the gonadotropin-releasing hormone (GnRH) surge for induction of the preovulatory luteinizing hormone surge of the ewe: dose-response relationship and excess of GnRH

The preovulatory LH surge in the ewe is stimulated by a large sustained surge of GnRH. We have previously demonstrated that the duration of this GnRH signal exceeds that necessary to initiate and sustain the LH surge. The objective of the present study was to determine whether a similar excess exists for amplitude of the GnRH surge. Experiments were performed using an animal model in which GnRH secretion was blocked by progesterone, which in itself does not block the pituitary response to GnRH. To assess the amplitude of the GnRH surge needed to induce the LH surge, we introduced artificial GnRH surges of normal contour and duration but varying amplitudes. Twelve ewes were run through 3 successive artificial follicular phases (total of 36). Six of these artificial follicular phases were positive controls, in which progesterone was removed, the estradiol stimulus was provided, and vehicle was infused. In these control cycles, animals generated endogenous LH surges. In the remaining artificial follicular phases, progesterone was not withdrawn, the estradiol stimulus was provided, and either vehicle (negative control) or GnRH solutions of varying concentrations (experimental) were infused. The circulating GnRH concentrations achieved by infusion were monitored. No LH surges were observed in negative controls, whereas LH surges were induced in experimental cycles provided a sufficient dose of GnRH was infused. A highly significant dose-response relationship was observed between the amplitude of the GnRH surge and both the amplitude of the LH surge and the area under the curve describing the LH response, but no such relationship existed between the amplitude of the GnRH surge and the duration of the LH response. In numerous cases, LH surges similar to those in the positive control animals resulted from infusion of amounts of GnRH estimated to be considerably less than those delivered to the pituitary during the endogenously generated GnRH/LH surge. These findings indicate that, in the ewe, increased GnRH secretion drives the preovulatory LH surge in a dose-dependent fashion, and they provide evidence that the amplitude of the GnRH surge may exceed that needed to generate the LH surge.     

Gene expression in a subpopulation of luteinizing hormone-releasing hormone (LHRH) neurons prior to the preovulatory gonadotropin surge

Gene expression in luteinizing hormone-releasing hormone (LHRH) neurons was analyzed during the periovulatory period to (1) characterize temporal patterns of LHRH gene expression and their relationship(s) to gonadotropin surges, and (2) determine if any such changes are uniform or dissimilar at different rostrocaudal levels of the basal forebrain. The number of neurons expressing mRNA for the decapeptide, and the relative degree of expression per cell were analyzed using in situ hybridization and quantitative image analysis. Rats were killed at 1800 hr on metestrus (Met), 0800 hr, 1200 hr, 1800 hr, and 2200 hr on proestrus (Pro), or 0200 hr, 0800 hr, and 1800 hr on estrus (E; n = 5-6 rats/group). All sections were processed for LHRH mRNA in a single in situ hybridization assay. Sections were atlas matched and divided into four rostrocaudal groups for analysis: vertical limb of the diagonal band of Broca (DBB), rostral preoptic area/organum vasculosum of the lamina terminalis (rPOA/OVLT), medial preoptic area (mPOA), and suprachiasmatic/anterior hypothalamic area (SCN/AHA). Plasma LH and FSH levels from all animals were analyzed by RIA. The labeling intensity per cell was similar among all time points at all four rostrocaudal levels. The number of cells expressing LHRH mRNA, however, varied as a function of time of death during the estrous cycle, and this temporal pattern varied among the four anatomical regions. At the level of the mPOA, the number of cells was highest at 1200 hr on Pro, and then declined and remained low throughout the morning of E. At the level of the rPOA/OVLT, the greatest number of LHRH neurons was noted later in Pro, at 1800 hr, dropping rapidly to lowest numbers at 2200 hr. No significant changes in LHRH cell number occurred at the DBB or SCN/AHA levels. At all anatomical levels, the secondary surge of FSH was unaccompanied by any change in the number of neurons expressing LHRH mRNA. These data demonstrate that (1) the number of detectable LHRH mRNA-expressing cells fluctuates during the periovulatory period and (2) peak numbers of LHRH-expressing cells are attained in the mPOA before the onset of the LH surge and before peak LHRH cell numbers are seen at more rostral levels. A model is proposed in which gene expression in this subpopulation of LHRH neurons may be activated by preovulatory estrogen secretion and acutely reduced following the proestrous surge of progesterone.     

Expression of growth hormone secretagogue-receptors by growth hormone-releasing hormone neurons in the mediobasal hypothalamus

A novel class of synthetic compounds, termed GH-secretagogues (GHSs), have been shown to be potent stimulators of GH release, although their mechanism of action and functional significance remains obscure. The recent cloning of the rat GHS receptor (GHS-R) permitted the identification of numerous sites of expression of GHS-R in brain, but nothing is yet known about the cell types that express this receptor. We performed dual chromogenic and autoradiographic in situ hybridization to test the hypothesis that GHRH neurons in the hypothalamus coexpress GHS-R mRNA. GHS-R-hybridizing cells showed extensive overlap with GHRH-expressing neurons in both the arcuate (Arc) and ventromedial (VMN) hypothalamic nuclei. Quantification of the double-labeled cells revealed that approximately 27% of GHRH-hybridizing neurons in the Arc, and 22% of those in the VMN, expressed the GHS-R gene. These studies are the first to colocalize the GHS-R to any neurochemical cell type in rat brain. The results provide evidence that the GHSs may directly modulate GHRH release, and thereby stimulate GH secretion, through interaction with the GHS-R on hypothalamic GHRH mRNA-containing neurons.     

Glucose availability modulates the timing of the luteinizing hormone surge in the ewe

To determine if glucose availability modulates the timing of the positive feedback action of oestrogen on gonadotropin secretion, we monitored the estradiol-induced luteinizing hormone (LH) surge in sheep (n = 5/group) made transiently hypoglycemic by insulin. Experiment 1 determined an effective insulin treatment, one which would depress tonic LH secretion. Two injections of insulin (5 IU/kg iv) 4 h apart were found to induce extended hypoglycemia (10-13 h) and to decrease the LH pulse frequency for 8 h (5.0 +/-0.32 pulses/4 h before versus 2.5+/-0.34 pulses/4 h after insulin; P<0.05; mean +/- SEM). Using this same paradigm, experiment 2 determined the influence of the transient hypoglycemia on the LH surge mechanism. In control sheep, estradiol (subcutaneous implants at hour 0) evoked an LH surge with a latency period of 12.4+/-0.5 h. When insulin was administered either before (hours -4 and 0) or after the estradiol stimulus (hours 4 and 8, or 12 and 16), the onset of the LH surge was delayed to 29.0+/-2.4 h (average of all three time groups, P <0.05). Infusion of glucose from hours 12-30, along with insulin, prevented hypoglycemia and restored the normal timing of the oestrogen-induced LH surge to that of controls (15.4+/-0.93 h, P>0.05). These findings suggest that not only is the tonic mode of LH secretion sensitive to metabolic fuel availability, but the surge mode of LH secretion is as well.     

Gonadotropin-releasing hormone axons target the median eminence: in vitro evidence for diffusible chemoattractive signals from the mediobasal hypothalamus

The projection of GnRH neurons to the median eminence of the medial basal hypothalamus (MBH) is established early in development and is also seen when preoptic area-derived GnRH cell-containing grafts are placed in the third ventricle of hypogonadal mice. To further study the factors directing GnRH axonal targeting, we cultivated embryonic or postnatal day 1 preoptic area with a coexplant on collagen- and laminin-coated membranes in insert chambers. After 7 days of culture, GnRH-immunoreactive fibers extended significantly farther and in greater number onto the sector of membrane facing a MBH coexplant than in the opposite sector, but not toward coexplants of control tissue. Moreover, such effects were specific, as outgrowth of a general axonal population, immunoreactive for growth-associated protein 43 was not influenced by the presence of the MBH. Preferential GnRH outgrowth toward the MBH was established early and was maintained during 10 days of culture. The importance of substrate-derived guidance was also assessed with confocal microscopy. GnRH axons consistently traveled in the company of growth-associated protein 43-labeled axons, but only erratic associations were seen between GnRH and glial processes extending on the membrane. We suggest that although employing an axonal substrate, GnRH axons follow a diffusible chemoattractive signal(s) secreted by the MBH.     

Resistance of gonadotropin releasing hormone drive to sex steroid-induced suppression in hyperandrogenic anovulation

Women with hyperandrogenic anovulation (HAA) exhibit increased GnRH drive, as evidenced by a faster LH pulse frequency that slows in response to progestin-induced opioidergic tone. To determine whether increased GnRH-LH drive in HAA reflects altered sex steroid exposure caused by chronic anovulation or is an intrinsic hypothalamic attribute, we compared the pulsatile LH response to oral contraceptive (OC)-induced suppression in seven women with HAA, with that of seven eumenorrheic women (EW). LH levels were determined at 10-min intervals for 12 h after 19-21 days of OC use and 5-7 days after cessation. Testosterone, androstenedione, estradiol, FSH, and LH levels were determined at weekly intervals before, during, and after OC use. LH pulse number/12 h was higher (P < 0.001) in HAA during and after OCs, when compared with that of EW. Mean LH was increased in HAA before, during, and after OCs. Testosterone, androstenedione, and estradiol levels were higher in HAA before OCs, but they decreased to similar levels during OC use in both groups. FSH concentrations were similar before and during OCs but rose more after cessation of OCs in EW. These findings indicate that GnRH drive in HAA is resistant to OC-induced suppression and, therefore, could be an intrinsic hypothalamic attribute.     

Blockade of the oestrogen-induced luteinizing hormone surge in ovariectomized ewes by a highly selective opioid mu-receptor agonist: evidence for site of action

OBJECTIVE: We studied the course of pregnancy in women with epilepsy to identify possible risk factors which might complicate the epilepsies and pregnancy outcomes. MATERIAL AND METHODS: Data were collected retrospectively from the records of 151 pregnancies in 124 women with epilepsy from 1978-1992. Epilepsy variables were compared with that of non-pregnant women with epilepsy matched for age. Obstetric and neonatal variables were compared with those of all deliveries in the same unit from 1979-1992 (n=38,983). RESULTS: Pregnancy among patients with epilepsy was more likely to occur in women with relatively mild epilepsy. In 12% of the pregnancies, the women were untreated while 71% were on monotherapy. Twenty-one percent had increased seizure frequency during the pregnancy. Perinatal deaths among newborns of epileptic mothers (1.3%) was more frequent but not significantly increased compared to the background population of 0.5% (95% CI 0.2-4.7). A total of 5.3% had congenital malformations compared to 1.5% in the controls (95% CI 2.3-10.3). No neural tube defects were observed. Maternal treatment with phenytoin was significantly related to the occurrence of congenital malformations, P=0.04. CONCLUSIONS: Most women with epilepsy have an uncomplicated pregnancy and normal healthy offsprings. Maternal treatment with phenytoin might be associated with congenital malformations. No other risk factors could be identified.     

The midcycle gonadotropin surge in normal women occurs in the face of an unchanging gonadotropin-releasing hormone pulse frequency

The midcycle gonadotropin surge is a critical event in normal reproductive cycles and requires functional integration of the hypothalamus, pituitary, and ovary. To determine whether a change in GnRH frequency occurs coincident with the onset or termination of the surge in normal women, 20 studies were performed at a sampling interval of every 5 min for up to 36 h. The frequency of pulsatile GnRH secretion was assessed by the use of two surrogate markers of its secretion, LH and free alpha-subunit (FAS). The timing of the studies was prospectively determined by serial ultrasound and previous cycle history, whereas measurements of LH, FSH, estradiol, and progesterone in daily blood samples were used retrospectively to locate the frequent sampling study in relation to the day of ovulation in each individual. The frequent sampling studies were divided into late follicular phase (LFP; days -4 to -2) and early, mid-, and late portions of the midcycle surge (days -1 to 1) in relation to the 95% confidence limits of the LH peak derived from daily samples in 69 normal ovulatory women. The patterns of LH and FAS secretion were pulsatile at all times during the midcycle surge. The amplitude of LH pulsations increased from the LFP and early surge to the midportion of the midcycle surge (5.9 +/- 6 and 15.1 +/- 5 vs. 39.0 +/- 3 IU/L; P < 0.0001) and decreased from the mid- to the late portion of the surge (13.4 +/- 5 IU/L; P < 0.0001). Likewise, the amplitude of FAS pulse increased from the LFP and early surge to the midportion of the surge (82.4 +/- 59 and 153.1 +/- 50 vs. 421.4 +/- 35 ng/L; P < 0.0001) and decreased from the mid- to the late portion of the surge (190.8 +/- 49 ng/L; P < 0.0002). Although there was excellent concordance of pulsatile secretion of LH and FAS, significantly more pulses of FAS were detected than of LH (P < 0.0001). There was no change in frequency (expressed as interpulse interval) between the LFP and the early and midportions of the surge for LH (70.0 +/- 8, 67.5 +/- 7, and 65 +/- 5 min, respectively) or FAS (55.1 +/- 7, 54.6 +/- 6, and 60.0 +/- 4 min). However, there was an increase in LH interpulse interval (decrease in pulse frequency) in the late portion of the surge (87.0 +/- 6 min) compared to the early and midportions of the surge (P < 0.02 and P < 0.0005, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)     

Domperidone stimulates prolactin secretion in rats with complete destruction of the mediobasal hypothalamus

The H1-antagonist diphenhydramine can undergo direct glucuronidation at its tertiary amino group with formation of a quaternary ammonium glucuronide. The intraindividual variability in the amount of N-glucuronide excretion in urine was investigated in two female volunteers who repeatedly took single doses of 25 mg diphenhydramine hydrochloride without and with concomitant administration of ascorbic acid or ammonium chloride for urine acidification. Another two female and four male subjects underwent single tests without and with additional ascorbic acid. Diphenhydramine N-glucuronide quantities in urine differed significantly among subjects and ranged between 2.7% and 14.8% of the dose within 8 h. Neither ascorbic acid nor ammonium chloride significantly influenced the quantity of N-glucuronide in urine, but ammonium chloride, that in contrast to ascorbic acid proved effective in lowering urinary pH, increased the excretion of the parent drug.     

Growth hormone releasing peptides: a comparison of the growth hormone releasing activities of GHRP-2 and GHRP-6 in rat primary pituitary cells

In the present study, the effect of GHRP-2 on GH release was evaluated in rat primary pituitary cells, and the results were compared with those elicited by GHRP-6. In the rat system, GHRP-2, like GHRP-6, acts synergistically with GRF to release GH. Co-administration of GHRP-2 and GHRP-6 at maximal concentrations had no further effect on GH release than either one alone. The GHRP's were able to desensitize cells to each other, but not to GRF. The effect of GHRP-2 was inhibited by Peptide Antagonist, but was not affected by a GRF antagonist. In conclusion, GHRP-2 was found to stimulate GH release from rat pituitary cells via the same receptor and mechanism as GHRP-6, despite the structural difference between the peptides.     

Suppression of spermatogenesis in man induced by Nal-Glu gonadotropin releasing hormone antagonist and testosterone enanthate (TE) is maintained by TE alone

GnRH antagonists plus testosterone (T) suppress LH and FSH levels and inhibit spermatogenesis to azoospermia or severe oligozoospermia. High-dose T treatment alone has been shown to be an effective male contraceptive (contraceptive efficacy rate of 1.4 per 100 person yr). Combined GnRH antagonist and T induces azoospermia more rapidly and at a higher incidence than T alone; this combination has therefore been proposed as a prototype male contraceptive. However, because GnRH antagonists are expensive to synthesize and difficult to deliver, it would be desirable to rapidly suppress sperm counts to low levels with GnRH antagonist plus T and maintain azoospermia or severe oligozoospermia with T alone. In this study, 15 healthy men (age 21-41 yr) with normal semen analyses were treated with T enanthate (TE) 100 mg im/week plus 10 mg Nal-Glu GnRH antagonist sc daily for 12 weeks to induce azoospermia or severe oligozoospermia. At 12-16 weeks, 10 of 15 subjects had zero sperm counts, and 14 of 15 had sperm counts less than 3 x 10(6)/mL. The 14 who were suppressed on combined treatment were maintained on TE alone (100 mg/week im) for an additional 20 weeks. Thirteen of 14 subjects in the TE alone phase had sperm counts maintained at less than 3 x 10(6)/mL for 20 weeks. Ten remained persistently azoospermic or had sperm concentration of 0.1 x 10(6)/mL once during maintenance. Mean LH and FSH levels in the subjects were suppressed to 0.4+/-0.2 IU/L and 0.5+/-0.2 IU/L in the induction phase, which was maintained in the maintenance phase. The 1 subject who failed to suppress sperm counts during induction had serum LH and FSH reduced to 0.3 and 0.5 IU/L, respectively. The subject who failed to maintenance had LH and FSH suppressed to 1.0 and 0.2 IU/L, respectively, during the induction phase but these rose to 1.6 and 2.1 IU/L, respectively, during maintenance. Failure to suppress or maintain low sperm counts may be related to incomplete suppression of serum LH and FSH levels. We conclude that sperm counts suppressed with GnRH antagonist plus T can be maintained with relatively low dose TE treatment alone. This concept should be explored further in the development of effective, safe, and affordable hormonal male contraceptives.     

The role of neuropeptide Y (NPY) in the control of LH secretion in the ewe with respect to season, NPY receptor subtype and the site of action in the hypothalamus

Neuropeptide Y1-36 (NPY1-36) acts through Y1 and Y2 receptors while the C-terminal NPY fragments NPY18-36 and N-acetyl[Leu28,31]pNPY24-36 act only through the Y2 receptor. We have investigated the effects of intracerebroventricular (i.c.v.) administration of NPY1-36, NPY18-36 and N-acetyl[Leu28,31]pNPY24-36 on LH secretion in the ovariectomised (OVX) ewe. These peptides were administered into a lateral ventricle (LV) or the third ventricle (3V) of OVX ewes during the non-breeding and breeding seasons. Microinjections of NPY were also made into the preoptic area (POA) during both seasons to investigate the effects of NPY at the level of the GnRH cell bodies. Tamed sheep were fitted with 19 gauge guide tubes into the LV, 3V or the septo-preoptic area (POA). Jugular venous blood samples were taken every 10 min for 3 h. Sheep were then given NPY1-36 (10 micrograms), NPY18-36 (100 micrograms) or saline vehicle into the LV; N-acetyl[Leu28,31]pNPY24-36 (100 micrograms), NPY1-36 (10 micrograms or 100 micrograms), NPY18-36 (10 micrograms or 100 micrograms) or saline vehicle into the 3V, or NPY1-36 (1 microgram, 5 micrograms, 10 micrograms) into the POA. Blood sampling continued for a further 3 h. LH was measured in plasma by radioimmunoassay. LV or 3V injection of 10 micrograms NPY1-36 caused a small but significant (P < 0.025) increase in the interval from the last pre-injection pulse of LH to the first post-injection LH pulse during the breeding season. Other LH pulse parameters were not significantly affected. NPY18-36 did not produce any significant change in LH pulsatility when injected into the LV, and neither peptide had any effect on plasma prolactin or GH levels. There was a significant (P < 0.01) reduction in LH pulse frequency after 3V injection of 10 micrograms and 100 micrograms NPY and 100 micrograms NPY18-36. Pulse amplitude was reduced by 3V administration of the Y2 agonist, N-acetyl[Leu28-31]pNPY24-36 and 100 micrograms NPY18-36. When the amplitude of the first post-injection LH pulse was analysed, 10 micrograms NPY also had a significant (P < 0.05) suppressive effect. During the non-breeding season, 100 micrograms NPY1-36 (but not 10 micrograms) decreased (P < 0.01) LH pulse frequency. LH pulse amplitude was significantly (P < 0.01) decreased by 100 micrograms NPY18-36. Doses of 10 micrograms NPY1-36 and 100 micrograms NPY18-36 had greater inhibitory effects on pulse frequency during the breeding season but the suppressive effect of 100 micrograms NPY was similar between seasons. Microinjections of NPY into the POA decreased (P < 0.01) average plasma LH levels during the non-breeding season at a dose of 10 micrograms but did not significantly affect pulse frequency or amplitude. We conclude that a substantial component of the inhibitory action of NPY on LH secretion in the absence of steroids is mediated by the Y2 receptor. This inhibition is probably exerted by way of a presynaptic action on GnRH terminals in the median eminence as NPY does not modulate the frequency or amplitude of LH pulses at the level of the GnRH cell bodies in the POA.     

The site of estradiol sensitization of the gonadotrope is prior to calcium mobilization

In primary pituitary cell cultures prepared from ovariectomized rats, estradiol-17B (E2) sensitizes gonadotropes to stimulation of luteinizing hormone (LH) release by gonadotropin releasing hormone (GnRH). The calcium ionophore A23187, which stimulates LH release from the cells by Ca2+ mobilization at a post-receptor locus, and veratridine, which stimulates LH release by activation of endogenous ion channels, were used to localize the site of E2 action. Cells cultured in medium which was charcoal stripped (to remove steroids) or which contained 10(-8) M added E2 responded equally well to the ionophore and equally well to veratridine, indicating that the molecular locus of E2 action precedes Ca2+ mobilization. This type of analysis can be used to locate the site of action of compounds which alter the responsiveness of the pituitary to GnRH.     

The status of the gonadotropin releasing hormone test in differential diagnosis of delayed puberty in adolescents over 14 years of age

BACKGROUND: In patients with delayed puberty with a bone age less than 11 years in girls or 12 years in boys, the clinical and endocrinological examination allows the differentiation of patients with the various forms of hypergonadotropic hypogonadism, but not of patients with hypogonadotropic hypogonadism from more prevalent constitutional delay in puberty. Therefore, watchful waiting is generally recommended for differential diagnosis in patients with delayed puberty. On the other hand, the late onset of sexual hormone replacement in patients with hypogonadism will worsen their outcome. PATIENTS AND METHOD: Therefore, we decided to carry out a retrospective study in 105 adolescents who were examined because of short stature or delayed puberty, who were aged 14 to 22 years at first visit and in whom the differential diagnosis of delayed puberty was documented after an at least one-year follow-up in order to find out which endocrinological parameters could have effectively predicted the final diagnosis already at the first visit. RESULTS: Patients with hypogonadotropic hypogonadism differed from patients with constitutional delay in puberty by lower responses of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels to gonadotropin-releasing hormone stimulation (GnRH, 100 micrograms iv) (p < 0.01) as well as by smaller testicular volume (p < 0.05) and by lower testosterone levels (p < 0.01). Stimulated LH < 10 mU/ml differentiated patients with hypogonadotropic hypogonadism from constitutional delay in puberty with a sensitivity of 82% and a specificity of 98%. CONCLUSION: In patients with delayed puberty aged 14 years and older bone age usually exceeds 11 years in girls or 12 years in boys. It thus is in the range, in which normal adult responses of LH to GnRH can be expected. In contrast to patients aged less than 14 years, therefore, measuring GnRH-stimulated LH levels in these patients allows the rapid and effective differential diagnosis of delayed puberty.     

Reduced nicotinamide adenine dinucleotide phosphate-diaphorase activity in the paraventricular nucleus of the rat hypothalamus is modulated by estradiol

Leiomyomas represent 2% of gastric tumors. Commonly, gastric leiomyomas are clinically silent. Most often they become clinically apparent due to bleeding from ulceration of the overlying gastric mucosa. Surgical extirpation of the tumor is the standard treatment. Gastric leiomyomectomy was done routinely through open laparotomy until availability of laparoscopic equipment and techniques. Recently, there have been a few published reports regarding laparoscopic or laparoscopic-assisted removal of smooth muscle gastric tumors. There is little data, however, describing or discussing a laparoscopic approach to gastric leiomyomas located on the posterior gastric wall. We describe two different laparoscopic approaches to posterior wall gastric leiomyomas that we used in two patients. The postoperative recovery of both patients was remarkably quick and uneventful.