Orphanin FQ and glutamate connection in the regulation of gonadotropin-releasing hormone secretion in the preoptic area of conscious male rats

Utilizing the method of push-pull perfusion and radioimmunoassay (RIA), the secretory profile of gonadotropin-releasing hormone (GnRH) in the preoptic area (POA) and serum-luteinizing hormone (LH) levels were examined in conscious male rats after administration of [Nphe(1)]NC(1-13)NH(2), a competitive antagonists of the opioid receptor-like 1 receptor (ORL1 receptor) which is endogenous receptor for Orphanin FQ (OFQ). Glutamate release in the POA was also measured by high-performance liquid chromatography (HPLC) after perfusion of [Nphe(1)]NC(1-13)NH(2), i.e. NC13. The results showed that GnRH secretion from the POA and serum LH levels was increased significantly 40 min and 60 min, respectively after perfusion of 2 and 20 mmol/L NC13 in freely moving male rats (p<0.05). Pretreatment with a glutamate, N-methyl-D-aspartate (NMDA) receptor antagonist (MK-801, s.c., 0.2 mg/kg) abolished the increase of GnRH release in the POA induced by 2 mmol/L NC13. Additionally, 20 mmol/L NC13 significantly enhanced glutamate release in the POA at 40 min post-perfusion in a dose-dependent manner. These findings suggest that hypothalamic OFQ/ORL1 receptor system plays a role in the physiological inhibitory control of GnRH secretion in the POA of male rats, and provide evidence for involvement of an OFQ and glutamate pathway in the control of GnRH secretion.     

Age-related changes in the pattern of luteinizing hormone release induced in female rats by male rat urine

The release of luteinizing hormone (LH) in young (3–4 months) and aged (24–25 months) ovariectomized female Sprague-Dawley rats, s.c. implanted with a 17β-estradiol benzoate silastic capsule, was studied in the presence and absence of stimulation by exposure to male rat urine. After taking an initial blood sample at 12:00 (reference sample), either urine, collected from young adult male rats, or distilled water was poured into the female's cage. Blood samples were then collected hourly up to 18:00 via a catheterized jugular cannula. The concentration of LH in the plasma was measured by RIA. The basal plasma LH level in young control rats was found to increase significantly at 16:00 compared with the 12:00 reference sample while no statistically significant change in plasma LH concentration occurred in old controls over the same period. Male rat urine caused a significantly earlier (at 15:00) and prolonged (from 15:00 to 18:00) elevation of plasma LH in young rats compared with young controls. In contrast, exposure of old female rats to male rat urine resulted in no marked change in plasma LH levels. These results suggest that both basal LH release and the response to pheromonal stimulation by male rat urine may be modified with increasing age in female rats.     

Quinolinic acid stimulates luteinizing hormone secretion in female rats: evidence for involvement of N-methyl-D-aspartate-preferring receptors

Summary Pharmacological evidence suggests that endogenous excitatory amino acid neurotransmitters stimulate luteinizing hormone (LH) secretion in neonatal and adult rats. Recent studies have identified quinolinic acid (QUIN), an endogenous brain and peripheral metabolite of tryptophan, as a potent agonist at N-methyl-D-aspartate (NMDA)-preferring excitatory amino acid receptors. The present studies examined whether QUIN alters LH secretion in ovariectomized, estradiol-primed rats and whether such effects are mediated by specific amino acid receptor subtypes. In one experiment, animals received intracisternal injections of either quinolinic acid, N-methyl-DL-aspartate (NMA), aspartate (ASP), quisqualic acid (QA), or monosodium glutamate (GLU) five minutes prior to decapitation. In a second study, animals receiving central QUIN or NMA were treated simultaneously with either 2-amino-7-phosphonoheptanoic acid (APH) or kynurenic acid (KYA), both antagonists of NMDA-preferring receptors, or the quisqualate antagonist, glutamate diethyl ester (GDEE). Serum LH concentrations were measured by radioimmunoassay. Intracisternal administration of either QUIN or NMA resulted in an acute, dose-dependent increase of serum LH concentrations. Coadministration of APH blocked the effects of QUIN and NMA. QUIN stimulation of LH was also blocked by KYA, but not GDEE. Neither GLU nor ASP increased LH release, but QA did produce a small, significant elevation of LH. Light microscopic evaluation of brains showed no morphologic disturbance resulting from administration of these agents. The present results suggest that QUIN, or other endogenous ligands of NMDA-preferring receptors, may participate in the regulation of LH secretion in the adult female rat.This research was supported by National Research Service Award Postdoctoral Fellowship HD-06443 (MDJ); by NIH grant HD-13703 and NIH Research Career Development Award HD-00366 (WRC); by Biomedical Research Support grant GR RR-05423, and by USPHS grant NS-20509 (WOW)     

Location and distribution of Fos protein expression in rat hippocampus following acute moderate aerobic exercise

Hippocampal neurons are activated during endurance exercise; however, little attention has been given to the location and spatial distribution of these neurons. We have, therefore, used Fos protein expression to identify the location and distribution of hippocampal neurons that become activated during acute moderate aerobic exercise. Adult rats were assigned into trained running (TR), trained nonrunning (TNR), untrained nonrunning (UNR), and cage-bound (CB) groups. Rats in the TR and TNR groups were trained to run, for three 20-min running periods separated by 3 min rest, on a treadmill. Rats in the UNR group spent identical time on a nonactivated treadmill, while rats in the CB group remained in their home cages throughout the training and experimentation. After training to criterion performance for both TR and TNR groups, both groups were rested for 1 day. Rats in the TR were then run on the treadmill to criterion level, while those in TNR and UNR groups spent equivalent time on the nonactivated treadmill. Animals in all groups were then killed and their brains removed, sectioned, and processed for Fos protein immunocytochemistry. Fos-like immunoreactive (FLI) neurons were counted in the dentate and CA1-3 fields of the hippocampus. The total numbers of hippocampal FLI neurons, as well as FLI neurons in each hippocampal region, were compared among groups. The total numbers of FLI neurons in the hippocampus, as well as in individual regions, were significantly greater in the TR group compared with the other three groups. Similarly, significant differences were found between the TNR group when compared with UNR and CB groups. Conversely, a significant difference existed between UNR and CB only in the CA1 field, which may account for the significant difference in the total number of hippocampal FLI neurons between these two groups. These results show that Fos induction occurs in the hippocampus during moderate physical exercise. Furthermore, the importance of the incorporation of adequate controls to account for possible differences in expression of immediate early gene expression due to trained performing, trained nonperforming, and untrained groups is discussed. The results indicate that adequate control for nonexercise stimuli is necessary for studies of the effect of exercise on the brain when expression of immediate early genes such as c-fos is used as an outcome measure.     

电针上调食源性肥胖致不孕大鼠下丘脑弓状核内GnRH的表达

目的 探讨电针对食源性肥胖致不孕大鼠中枢性作用中,能否上调下丘脑弓状核GnRH的表达.方法 将100只刚断乳雌性SD大鼠随机分为2组:①正常组20只,喂以普通饲料;②高能饲料组80只,给予高能饲料,筛选出肥胖不孕大鼠22只,并将其随机分成两组,即对照组和电针组.检测血清雌二醇(E2)、睾酮(T)、瘦素(leptin) ...     

Sexually dimorphic age-related changes in the distribution of immunoreactive luteinizing hormone releasing hormone in the platyfish

In this study on platyfish we demonstrate that the distribution and intensity of immunoreactive luteinizing hormone releasing hormone (ir-LHRH) in the brain and pituitary gland fluctuate at specific ages between 8 and 30 months. These changes are not the same in males and females, and they vary for each LHRH-containing region in the brain. In males, ir-LHRH intensity is greatest in the nucleus olfactoretinalis (NOR), nucleus preopticus periventricularis (NPP) and nucleus lateralis tuberis (NLT) at 18 months of age. In females, by comparison, the NOR displays the same degree of immunoreactivity at all ages examined, as does the NLT, where ir-LHRH perikarya are absent at all ages and immunoreactivity is restricted to a few fibers. In the NPP, females show fluctuations similar to those seen in males, however, the intensity of ir-LHRH is always less, and the number of ir-LHRH perikarya appear to be fewer, than in males. Thus, the age-related changes in LHRH systems in platyfish follow different patterns in males and females. Our study clearly indicates that immunocytochemical data must be evaluated with caution and that only after the age and sex of the animal and the maturational state of the gonads have been carefully scrutinized, can meaningful interpretations be made.     

Distinct patterns of hippocampal formation activity associated with different spatial tasks: a Fos imaging study in rats

Fos levels were measured in rats trained in one of two qualitatively different spatial memory tasks in a water maze. In one task, (landmark condition) rats found a submerged platform that was always 25 cm south of a visible landmark, the absolute position of the platform and landmark changing after every trial. In the other task (place condition), rats swam to a platform that remained in the same absolute position on every session, but changed session to session, with this task relying on the memory of allocentric cues. Despite matched swim times, the landmark condition resulted in higher levels of Fos in a wide range of cortical and subcortical sites, including the hippocampus and its connections. Structural equation modelling revealed two different patterns of hippocampal function. In the allocentric place task there was a significant association between Fos activity in the entorhinal cortices and the hippocampus proper, while in the non-allocentric landmark task this relationship was not present, but was replaced by a connection from the entorhinal cortices to the subiculum. Thus, the two different tasks engage two different modes of hippocampal activity as demonstrated by Fos expression.     

The effect of Δ1tetrahydrocannabinol on luteinizing hormone release in castrated and hypothalamic deafferented male rats

Summary ¹Tetrahydrocannabinol (THC) acutely suppresses tonic serum luteinizing hormone (LH) and prolactin levels in adult male rats. The exact site of its action has not been identified. We have performed complete hypothalamic deafferentation (CHD), which disrupts the medial basal hypothalamus (MBH) from the rest of the CNS, but did not abolish the abilitiy of THC to suppress hypothalamic-pituitary responses in gonadectomized male rats. This was shown by the equal reduction in serum levels of LH and prolactin in non-deafferented (ND) and CHD animals. These results indicate that THC is able to act inside the MBH and that the MBH-pituitary axis remains responsive to its inhibitory effect despite interruption of the neural connections between the MBH and extrahypothalamic areas. However, the corticotropin releasing factor neurons in the MBH appear functionally impaired as a result of the transection and become unresponsive to the normally produced THC stimulation. Different patterns of action seem to govern the various hypophyseal hormones controlled by the hypothalamus, suggesting that the release of LH releasing hormone and prolactin inhibiting factor might be maintained by the activity of neurons surviving inside the island.     

β-Endorphin/β-lipotropin release and gonadotropin secretion after acute exercise in physically conditioned males

Summary β-endorphin (β-EP) andβ-lipotropin (β-LPH) concentrations were measured in the basal state and after acute exercise for 15 min or until exhaustion in 6 physically conditioned male volunteers. Serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone and prolactin were also measured in the basal state. In addition, the concentrations of the gonadotropins (LH and FSH) were determined after exercise and the gonadotropin response to gonadotropin releasing hormone was assessed before and after exercise. The data show that acute exercise stimulates the release of bothβ-EP andβ-LPH which return to base-line levels within 60 min after exercise. This is in contrast to our previously described results in physically unconditioned male volunteers in whom onlyβ-LPH release was noted after exercise. Serum LH concentrations declined after exercise reaching nadir values between 60 to 150 min after exercise. As we previously reported in physically unconditioned male volunteers, serum FSH concentrations did not change with exercise and the gonadotropin response to LRH stimulation was uninfluenced by exercise. Serum testosterone and prolactin concentration were within the normal range for healthy adult males. We speculate that the difference inβ-EP release with exercise in physically conditioned and unconditioned males represents a difference in processing of the opioid precursor molecule (pro-opiomelanocortin, POMC) in the two groups.     

Heme oxygenase-derived carbon monoxide modulates gonadotropin-releasing hormone release in immortalized hypothalamic neurons

Heme oxygenase (HO), the main enzyme deputed to heme metabolism, has been identified as two main isoforms called HO-1 and HO-2 both present in the central nervous system. Heme oxygenase has been shown to regulate the hypothalamic release of neuropeptides such as corticotrophin-releasing hormone and arginin-vasopressin. The aim of this study was to investigate and further characterize the presence of HO in gonadotropin-releasing hormone (GnRH) secreting hypothalamic neurons, GT1-7 and the role of HO by-products on GnRH secretion. The pulsatile release of GnRH from scattered hypothalamic neurons is the key regulator of mammalian fertility in the central nervous system. GT1-7 cells are immortalized hypothalamic neurons, characterized by spontaneous electrical activity and pulsatile GnRH release, resembling the central control pathway of the hypothalamic pituitary gonadal axis (HPG) in mammals. Hemin, the substrate of HO, significantly stimulated HO activity in static cultures, causing a rapid increase in GnRH release. Neither biliverdin nor bilirubin were able to mimic this rapid stimulatory effect, which was instead caused by carbon monoxide. Evidence of a possible involvement of prostaglandin E₂ in the HO by-product modulated GnRH secretion was reported. The hemin-evoked effect on GT1-7 neurons suggests a direct activity of HO by-products on the hypothalamic neuropeptide secretion, and claims for a possible role of CO in both the modulation of gonadotropin secretion and crosstalk among HPG and stress axis within the mammalian hypothalamus.     

Immunocytochemical localization of luteinizing hormone-releasing hormone in neurons in the medial basal hypothalamus of the female rat

Summary Luteinizing hormone-releasing hormone (LHRH)-neurons were localized with a LHRH antiserum (WP-1) in the medial basal hypothalamus (MBH) of the female rat using the sagittal hypothalamic slice preparation in combination with the peroxidase-antiperoxidase immunocytochemical technique of Sternberger (1979). Numerous darklystained perikarya were visualized in the cell-poor zone, lateral arcuate nucleus and the median eminence. The processes of these neurons contributed to the intensely-stained fiber bundle above the tubero-infundibular sulcus. The fibers in this tract run in a rostrocaudal plane in the lateral external zone of the median eminence. Also, numerous fibers course into the internal zone of the median eminence, perpendicular to the rostrocaudal plane. Several LHRH-immunoreactive perikarya also were identified in the periventricular area caudal to the optic chiasm (retrochiasmatic area). The LHRH neurons were small (10 m) bipolar neurons with fibers (dendrites) exiting from either pole which showed very little branching. It appears that the sagittal slice in combination with the appropriate fixation procedure and LHRH antiserum enabled us to demonstrate the presence of LHRH-immunoreactive perikarya in the MBH of the female rat.Supported by Health Research Services Foundation Grant W-22 and NIH Grant NS16419     

卵泡刺激素与卵泡刺激素及黄体生成素共同干预对玻璃化冻存小鼠卵巢组织血管内皮生长因子表达的影响

目的 通过在玻璃化冻存全程给予小鼠卵巢组织卵泡刺激素（FSH）及FSH和黄体生成素（LH）共同干预,观察冻融卵巢组织的形态学改变以及两种激素干预对冻存卵巢组织血管内皮生长因子（VEGF）表达的影响,寻找最佳的提高冻融卵巢组织卵泡存活及VEGF表达的激素干预方式。 方法 4周龄C57BL/6J小鼠卵巢组织分为新鲜对照组（CG）,玻璃化冻存对照组（VCG）,300IU/L FSH全程干预玻璃化冻存组（OG-FSH）,以及150IU/L FSH+150IU/L LH全程干预玻璃化冻存组(OG-FSH+LH),每组30个卵巢样本。通过常规组织学、Western blotting技术,观察并分析各组卵巢组织形态结构改变及VEGF蛋白表达量;通过荧光定量PCR技术(Real-time PCR)检测VEGF mRNA表达情况。 结果 OG-FSH+LH 组正常卵泡百分比最高,且显著高于OG-FSH组（P<0.05）;VEGF蛋白表达量在OG-FSH+LH组显著高于OG-FSH组（P<0.05）;荧光定量PCR检测结果表现为VEGF mRNA表达量在OG-FSH+LH组最高,其次为OG-FSH组,最低是VCG组（P<0.05）。 结论 玻璃化冻存全程添加FSH+LH的干预方式较单独FSH干预具有更高正常卵泡百分比和更佳的VEGF蛋白表达。     

Corticotropin releasing hormone and gonadotropin secretion in physically active males after acute exercise

Summary Plasma concentrations of corticotropin releasing hormone (CRH) and the serum concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, adrenocorticotropic hormone (ACTH) and cortisol were measured in seven physically active males after acute exercise on a treadmill using the Bruce protocol. Measurements were made in the basal pre-exercise state, immediately after exercise, and at 30-min intervals for 3 h after exercise. Serum LH concentrations declined following exercise reaching nadir values between 60 and 180 min after exercise (90 min post exercise in the group). The nadir values in individual volunteers were significantly lower than both the baseline and post-exercise levels. This fall in serum LH concentration appeared to follow a slight but significant elevation of the plasma concentration of CRH which reached peak levels when measured immediately post exercise. Plasma ACTH concentrations paralleled the rise in CRH, but fell to undetectable levels of below 13.8 nmol · l^–1 (< 5 ng · l^–1) 60 min after exercise. Plasma cortisol concentrations peaked approximately 30 min after the rise in ACTH, after which they gradually declined to baseline levels. Plasma testosterone concentrations paralleled the concentrations of LH. The data suggest that CRH, on the basis of its previously described gonadotropin-depressant property, may be the hormone involved in the exercise-mediated decline in serum LH. Alternatively, some as yet unidentified factor(s), may be involved in producing the altered concentrations of both LH and CRH.     

促性腺激素释放激素类似物对乳腺癌细胞株化疗敏感性的影响

目的： 探讨促性腺激素释放激素类似物（GnRHa）对乳腺癌细胞株（MCF-7和MDA-MB-231）化疗敏感性的影响。方法：不同浓度的GnRHa（曲普瑞林,triptorelin）（10^－9 mol/L、10^－8 mol/L、10^－7 mol/L、10^－6 mol/L、10－5 mol/L）分别作用于MCF-7和MDA-MB-231细胞24 h、96 h和168 h后，用CCK-8方法检测细胞活性。用或不用GnRHa（10^－5 mol/L）处理96 h后，分别加入5-氟尿嘧啶（5-FU）或表阿霉素(EPI)作用24 h，用CCK-8法检测细胞抑制率。用RT-PCR检测GnRHa（10^－5 mol/L）作用168 h后GnRH受体、PCNA和MDR1 mRNA表达水平。结果：不同浓度GnRHa作用不同的时间后对乳腺癌细胞活性无影响。GnRHa（10^－5 mol/L）作用96 h后，5－FU和EPI对两种细胞的IC50不改变；GnRHa（10^－5 mol/L）不影响5－FU（MCF-7细胞0.5 g/L，MDA－MB－231细胞0.5 g/L）和EPI（MCF-7细胞1.2 mg/L,MDA－MB－231细胞0.8 mg/L）对两种细胞的抑制作用（P>0.05）。GnRHa（10^－5 mol/L）作用168 h后，MCF-7细胞的PCNA mRNA表达无改变。而在MDA-MB-231细胞，PCNA表达升高，差别有统计学意义（P<0.05）。在MCF-7对照组中，MDR1 mRNA有弱表达。GnRHa作用后，抑制了MDR1 mRNA表达。MDA-MB-231细胞GnRHa作用前后， MDR1 mRNA均无表达。结论：GnRHa不影响乳腺癌细胞株对5-FU和EPI的敏感性。GnRHa可能通过下调MDR1 mRNA表达水平，减弱MCF-7细胞的耐药性。     

Fos expression following regimens of predator stress versus footshock that differentially affect prepulse inhibition in rats

Stress is suggested to exacerbate symptoms and contribute to relapse in patients with schizophrenia and several other psychiatric disorders. A prominent feature of many of these illnesses is an impaired ability to filter information through sensorimotor gating processes. Prepulse inhibition (PPI) is a functional measure of sensorimotor gating, and known to be deficient in schizophrenia and sometimes in post-traumatic stress disorder (PTSD), both of which are also sensitive to stress-induced symptom deterioration. We previously found that a psychological stressor (exposure to a ferret without physical contact), but not footshock, disrupted PPI in rats, suggesting that intense psychological stress/trauma may uniquely model stress-induced sensorimotor gating abnormalities. In the present experiment, we sought to recreate the conditions where we found this behavioral difference, and to explore possible underlying neural substrates. Rats were exposed acutely to ferret stress, footshock, or no stress (control). 90 min later, tissue was obtained for Fos immunohistochemistry to assess neuronal activation. Several brain regions (prelimbic, infralimbic, and cingulate cortices, the paraventricular hypothalamic nucleus, the paraventricular thalamic nucleus, and the lateral periaqueductal gray) were equally activated following exposure to either stressor. Interestingly, the medial amygdala and dorsomedial periaqueductal gray had nearly twice as much Fos activation in the ferret-exposed rats as in the footshock-exposed rats, suggesting that higher activation within these structures may contribute to the unique behavioral effects induced by predator stress. These results may have implications for understanding the neural substrates that could participate in sensorimotor gating abnormalities seen in several psychiatric disorders after psychogenic stress.     

Detection of gonadotropin-releasing hormone receptor in normal human pituitary cells and pituitary adenomas using immunohistochemistry

Gonadotropin-releasing hormone (GnRH), which is a well-known regulator of gonadotroph function, has recently been considered to be a paracrine factor involved in the control of somatotroph, lactotroph, and corticotroph cells. GnRH action is initiated by binding to a specific cell surface receptor, the gonadotropin-releasing hormone receptor (GnRHR), which is expressed by follicle-stimulating hormone/luteinizing hormone (FSH/LH) cells. Using in situ hybridization techniques, GnRHR messenger ribonucleic acid (mRNA) has recently been detected in normal human anterior pituitary gland and in various pituitary adenomas, including FSH/LH-cell, growth hormone (GH)-cell, adrenocorticotropic hormone (ACTH)-cell, and null-cell adenomas. However, immunohistochemical studies indicating the specific cell distribution of GnRHR in normal pituitary cells have never been reported. The aim of the present investigation was to evaluate the immunohistochemical expression of GnRHR in different types of normal pituitary cells and related tumors. Using double-label immunohistochemical techniques on formalin-fixed and paraffin-embedded tissues and specific antibodies directed against pituitary hormones and GnRHR, we found GnRHR immunoreactivity not only in FSH/LH cells, but also in GH- and thyroid-stimulating hormone (TSH) cells. GnRHR was detected in FSH/LH-cell, GH-cell, mixed GH- and prolactin (PRL)-cell, and α-subunit (α-SU)/null-cell adenomas. The findings of this study suggest that the interaction between GnRH and GnRHR may play a role in paracrine/autocrine regulation of different types of normal pituitary cells and pituitary adenomas. Received: 24 January 2000 / Accepted: 12 April 2000     

缝隙连接蛋白43和黄体生成素受体在小鼠卵巢中的表达

目的 观察小鼠卵泡发育过程中缝隙连接蛋白43（Cx43）和黄体生成素受体（LHR）在小鼠卵巢中的表达以及黄体生成素(LH)对卵巢Cx43表达的影响,为这两种分子与卵泡发育的关系提供实验依据。 方法 选择出生后1d、4d、7d、2周、3周、4周、6周、8周龄雌性C57小鼠共8组,每组10只,取卵巢。HE染色观察卵巢形态、卵泡发育并测量颗粒细胞体积分数。免疫组织化学和Western blotting观察卵巢组织中Cx43及LHR的表达,Western blotting检测不同浓度黄体生成素（LH）孵育后对卵巢Cx43表达的影响。 结果 HE染色显示,出生1d小鼠卵巢中见原始卵泡,出生7d卵巢内出现初级卵泡,2周时出现窦前卵泡和少量窦卵泡,3周、4周时,出现较多大的窦卵泡,6～8周时出现黄体。卵泡颗粒细胞体积分数在2周后的卵巢中明显增加。Cx43表达在各阶段卵泡的颗粒细胞胞膜上,LHR表达在卵泡膜细胞、颗粒细胞及卵母细胞胞质中。Cx43和LHR出生后2周卵巢中的表达开始明显增加,并随卵泡发育表达逐渐增强,在3周、4周、6周和8周维持相对较高水平。LH体外干预可增加卵巢组织Cx43的表达。 结论 Cx43和LHR在卵泡发育中发挥重要作用,LH可能通过LHR促进卵巢卵泡颗粒细胞Cx43的表达。