scholarly journals Interactions between kisspeptin and neurokinin B in the control of GnRH secretion in the female rat

2011 ◽  
Vol 300 (1) ◽  
pp. E202-E210 ◽  
Author(s):  
Víctor M. Navarro ◽  
Juan M. Castellano ◽  
Sarah M. McConkey ◽  
Rafael Pineda ◽  
Francisco Ruiz-Pino ◽  
...  
Keyword(s):  
Critical Role ◽  
Fold Increase ◽  
Serum Levels ◽  
Female Rat ◽  
Neurokinin B ◽  
Hypothalamic Nuclei ◽  
Lh Secretion ◽  
Circulating Levels ◽  
Lateral Cerebral Ventricle

Neurokinin B (NKB) and its cognate receptor neurokinin 3 (NK3R) play a critical role in reproduction. NKB and NK3R are coexpressed with dynorphin ( Dyn) and kisspeptin ( Kiss1) genes in neurons of the arcuate nucleus (Arc). However, the mechanisms of action of NKB as a cotransmitter with kisspeptin and dynorphin remain poorly understood. We explored the role of NKB in the control of LH secretion in the female rat as follows. 1) We examined the effect of an NKB agonist (senktide, 600 pmol, administered into the lateral cerebral ventricle) on luteinizing hormone (LH) secretion. In the presence of physiological levels of estradiol (E2), senktide induced a profound increase in serum levels of LH and a 10-fold increase in the number of Kiss1 neurons expressing c -fos in the Arc ( P < 0.01 for both). 2) We mapped the distribution of NKB and NK3R mRNAs in the central forebrain and found that both are widely expressed, with intense expression in several hypothalamic nuclei that control reproduction, including the Arc. 3) We studied the effect of E2 on the expression of NKB and NK3R mRNAs in the Arc and found that E2 inhibits the expression of both genes ( P < 0.01) and that the expression of NKB and NK3R reaches its nadir on the afternoon of proestrus (when circulating levels of E2 are high). These observations suggest that NKB/NK3R signaling in Kiss1/NKB/Dyn-producing neurons in the Arc has a pivotal role in the control of gonadotropin-releasing hormone (GnRH)/LH secretion and its regulation by E2-dependent negative feedback in the rat.

scholarly journals The possible role of Interleukin-6 as a regulator of insulin sensitivity in patients with neuromyelitis optica spectrum disorder

BMC Neurology ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhila Maghbooli ◽  
Abdorreza Naser Moghadasi ◽  
Nasim Rezaeimanesh ◽  
Abolfazl Omidifar ◽  
Tarlan Varzandi ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Neuromyelitis Optica ◽  
Serum Levels ◽  
Spectrum Disorder ◽  
Control Group ◽  
Neuromyelitis Optica Spectrum Disorder ◽  
Downstream Signaling ◽  
Reduce Insulin Sensitivity ◽  
Circulating Levels

Abstract Background Neuromyelitis optica spectrum disorder (NMOSD) is associated with inflammatory mediators that may also trigger downstream signaling pathways leading to reduce insulin sensitivity. Methods We aimed to determine the risk association of hyperinsulinemia in NMOSD patients with seropositive AQP4-IgG and the serum levels of interleukin (IL)-6 and IL-17A compared with the control group. Serum levels of metabolic (Insulin, Fasting Blood Sugar (FBS), lipid profile) and inflammatory (IL-6 and IL-17) markers were assessed in 56 NMOSD patients and 100 controls. Results Hyperinsulinemia was more prevalent in NMOSD patients independent of age, sex and body mass index (BMI) (48.2% vs. 26%, p = 0.005) compared to control group. After adjusting age, sex and BMI, there was significant association between lower insulin sensitivity (IS) and NMOSD risk (95% CI: Beta = 0.73, 0.62 to 0.86, p = 0.0001). Circulating levels of IL-6 and IL-17 were higher in NMOSD patients, and only IL-6 had an effect modifier for the association between lower insulin sensitivity and NMOSD risk. Conclusions Our data suggests that inflammatory pathogenesis of NMOSD leads to hyperinsulinemia and increases the risk of insulin resistance.

scholarly journals Levels of Circulating PD-L1 Are Decreased in Patients with Resectable Cholangiocarcinoma

2021 ◽  
Vol 22 (12) ◽  
pp. 6569
Author(s):  
Christoph Roderburg ◽  
Sven H. Loosen ◽  
Jan Bednarsch ◽  
Patrick H. Alizai ◽  
Anjali A. Roeth ◽  
...  
Keyword(s):  
Tumor Recurrence ◽  
Tumor Biology ◽  
Tumor Resection ◽  
Postoperative Outcome ◽  
Serum Levels ◽  
Strong Trend ◽  
Programmed Cell Death 1 ◽  
Early Tumor ◽  
Circulating Levels

Tumor resection represents the only curative treatment option for patients with biliary tract cancers (BTCs), including intrahepatic cholangiocarcinoma (CCA), perihilar and extrahepatic CCA and gallbladder cancer. However, many patients develop early tumor recurrence and are unlikely to benefit from surgery. Therefore, markers to identify ideal surgical candidates are urgently needed. Circulating programmed cell death 1 ligand 1 (PD-L1) has recently been associated with different malignancies, including pancreatic cancer which closely resembles BTC in terms of patients’ prognosis and tumor biology. Here, we aim at evaluating a potential role of circulating PD-L1 as a novel biomarker for resectable BTC. Methods: Serum levels of PD-L1 were analyzed by ELISA in 73 BTC patients and 42 healthy controls. Results: Circulating levels of preoperative PD-L1 were significantly lower in patients with BTC compared to controls. Patients with low PD-L1 levels displayed a strong trend towards an impaired prognosis, and circulating PD-L1 was negatively correlated with experimental markers of promalignant tumor characteristics such as CCL1, CCL21, CCL25 and CCL26. For 37 out of 73 patients, postoperative PD-L1 levels were available. Interestingly, after tumor resection, circulating PD-L1 raised to almost normal levels. Notably, patients with further decreasing PD-L1 concentrations after surgery showed a trend towards an impaired postoperative outcome. Conclusion: Circulating PD-L1 levels were decreased in patients with resectable BTC. Lack of normalization of PD-L1 levels after surgery might identify patients at high risk for tumor recurrence or adverse outcome.

scholarly journals Investigating the role of noncoding regulatory DNA in plasmid development for Yarrowia lipolytica

2020 ◽  
Author(s):  
Carmen Lopez ◽  
Mingfeng Cao ◽  
Zhanyi Yao ◽  
Zengyi Shao
Keyword(s):  
Yarrowia Lipolytica ◽  
Plasmid Stability ◽  
Critical Role ◽  
Fold Increase ◽  
Microbial Cell Factories ◽  
Cell Factories ◽  
Expression Platform ◽  
Regulatory Dna ◽  
Selection Of

Production of industrially relevant compounds in microbial cell factories can employ either genomes or plasmids as an expression platform. Selection of plasmids as pathway carriers is advantageous for rapid demonstration but poses a challenge of stability. Yarrowia lipolytica has attracted great attention in the past decade for the biosynthesis of chemicals related to fatty acids at titers attractive to industry, and many genetic tools have been developed to explore its oleaginous potential. Our recent studies on the autonomously replicating sequences (ARSs) of nonconventional yeasts revealed that the ARSs from Y. lipolytica showcase a unique structure that includes a previously unannotated sequence (spacer) linking the origin of replication (ORI) and the centromeric (CEN) element and plays a critical role in modulating plasmid behavior. Maintaining a native 645-bp spacer yielded a 4.5-fold increase in gene expression and higher plasmid stability compared to a more universally employed minimized ARS. Testing the modularity of the ARS sub-elements indicated that plasmid stability exhibits a pronounced cargo dependency. Instability caused both plasmid loss and intramolecular rearrangements. Altogether, our work clarifies the appropriate application of various ARSs for the scientific community and sheds light on a previously unexplored DNA element as a potential target for engineering Y. lipolytica.

Glucocorticoids in the Physiological and Transcriptional Regulation of 5-HT1A Receptor and the Pathogenesis of Depression

2020 ◽  
pp. 107385842097571
Author(s):  
Darakhshan Jabeen Haleem
Keyword(s):  
Transcriptional Regulation ◽  
Critical Role ◽  
Treatment Strategies ◽  
Therapeutic Agents ◽  
Stressful Events ◽  
Antagonist Activity ◽  
Treatment Of Depression ◽  
Prevalence Of Depression ◽  
Circulating Levels

There is growing increase in the global prevalence of depression, but treatment outcome of this highly disabling disease is not satisfactory. Many patients are not benefitted by the currently prescribed antidepressants—together with this partial remission is very common. Improving treatment strategies and developing better therapeutic agents for treating depression is therefore highly needed. Stress-related epigenetic changes play a critical role in the pathogenesis as well as treatment of depression. Stressful events activate hypothalamic-pituitary-adrenal axis to increase circulating levels of glucocorticoids (GCs), and a greater sensitivity to this fright and flight response increases risk of depression. A role of serotonin (5-hydroxytryptamine; 5-HT) in responses to stress and in the pathogenesis and treatment of depression is well established. Substantial evidence supports a critical role of 5-HT1A receptors in these effects of 5-HT. The present article targets stress-induced higher and sustained increases of GCs and mediated influences on the physiological as well transcriptional regulation of 5-HT1A receptors to evaluate their causal role in the pathogenesis of depression. It is suggested that synthetic compounds with antagonist activity for GC receptors and agonist activity for 5-HT1A receptors may prove better therapeutic agents for treating depression.

scholarly journals Kisspeptin and neurokinin B interactions in modulating gonadotropin secretion in women with polycystic ovary syndrome

2020 ◽  
Vol 35 (6) ◽  
pp. 1421-1431
Author(s):  
Karolina Skorupskaite ◽  
Jyothis T George ◽  
Johannes D Veldhuis ◽  
Robert P Millar ◽  
Richard A Anderson
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Clinical Research ◽  
Polycystic Ovary ◽  
Pulse Frequency ◽  
Research Facility ◽  
Neurokinin B ◽  
Ovary Syndrome ◽  
Clinical Research Facility ◽  
Lh Secretion

Abstract STUDY QUESTION What is the role of the hypothalamic neuropeptide neurokinin B (NKB) and its interaction with kisspeptin on GnRH/LH secretion in women with polycystic ovary syndrome (PCOS)? SUMMARY ANSWER Administration of neurokinin 3 receptor antagonist (NK3Ra) for 7 days reduced LH and FSH secretion and LH pulse frequency in women with PCOS, whilst the stimulatory LH response to kisspeptin-10 was maintained. WHAT IS KNOWN ALREADY PCOS is characterized by abnormal GnRH/LH secretion. NKB and kisspeptin are master regulators of GnRH/LH secretion, but their role in PCOS is unclear. STUDY DESIGN, SIZE, DURATION The NK3Ra MLE4901, 40 mg orally twice a day, was administered to women with PCOS for 7 days (n = 8) (vs no treatment, n = 7). On the last day of NK3Ra administration or the equivalent day in those not treated, women were randomized to 7-h kisspeptin-10 (4 µg/kg/h i.v.) or vehicle infusion. This was repeated with the alternate infusion in a subsequent cycle. PARTICIPANTS/MATERIALS, SETTING, METHODS Subjects were women with PCOS, studied in a Clinical Research Facility. Reproductive hormones were measured before and after NK3Ra administration. On the last day of NK3Ra administration (or the equivalent cycle day in untreated women), all women attended for an 8-h frequent blood sampling to allow analysis of the pulsatile LH secretion. MAIN RESULTS AND THE ROLE OF CHANCE NK3Ra reduced LH secretion (4.0 ± 0.4 vs 6.5 ± 0.8 IU/l, P &lt; 0.05) and pulse frequency (0.5 ± 0.1 vs 0.8 ± 0.1 pulses/h, P &lt; 0.05); FSH secretion was also reduced (2.0 ± 0.3 vs 2.5 ± 0.4 IU/l, P &lt; 0.05). Without NK3Ra pre-treatment, kisspeptin-10 increased LH secretion (5.2 ± 0.5 to 7.8 ± 1.0 IU/L, P &lt; 0.05), with a positive relationship to oestradiol concentrations (r2 = 0.59, P &lt; 0.05). After NK3Ra administration, the LH response to kisspeptin-10 was preserved (vehicle 3.5 ± 0.3 vs 9.0 ± 2.2 IU/l with kisspeptin-10, P &lt; 0.05), but the positive correlation with oestradiol concentrations was abolished (r2 = 0.07, ns. after NK3Ra). FSH secretion was increased by kisspeptin-10 after NK3Ra treatment, but not without NK3Ra treatment. LIMITATIONS, REASONS FOR CAUTION The study did not explore the dose relationship of the effect of NK3R antagonism. The impact of obesity or other aspects of the variability of the PCOS phenotype was not studied due to the small number of subjects. WIDER IMPLICATIONS OF THE FINDINGS These data demonstrate the interactive regulation of GnRH/LH secretion by NKB and kisspeptin in PCOS, and that the NKB system mediates aspects of oestrogenic feedback. STUDY FUNDING/COMPETING INTEREST(S) Wellcome Trust through Scottish Translational Medicine and Therapeutics Initiative (102419/Z/13/A) and MRC grants (G0701682 to R.P.M. and R.A.A.) and MR/N022556/1 to the MRC Centre for Reproductive Health. This work was performed within the Edinburgh Clinical Research Facility. J.T.G. has undertaken consultancy work for AstraZeneca and Takeda Pharmaceuticals and is an employee of Boehringer Ingelheim. R.P.M. has consulted for Ogeda and was CEO of Peptocrine. R.A.A. has undertaken consultancy work for Merck, Ferring, NeRRe Therapeutics and Sojournix Inc. J.D.V. and K.S. have nothing to disclose. TRIAL REGISTRATION NUMBER N/A.

scholarly journals Phosphinic peptides, the first potent inhibitors of astacin, behave as extremely slow-binding inhibitors

1998 ◽  
Vol 331 (2) ◽  
pp. 375-379 ◽  
Author(s):  
Irene YIALLOUROS ◽  
Stamatia VASSILIOU ◽  
Athanasios YIOTAKIS ◽  
Robert ZWILLING ◽  
Walter STÖCKER ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Critical Role ◽  
Fold Increase ◽  
Rational Basis ◽  
Inhibitor Binding ◽  
Parent Molecule ◽  
Transition State Analogue ◽  
Morphogenetic Protein ◽  
Binding Behaviour

A series of phosphinic pseudo-peptides varying in length and composition have been designed as inhibitors of the crayfish zinc endopeptidase astacin, the prototype of the astacin family and of the metzincin superfamily of metalloproteinases. The most efficient phosphinic peptide, fluorenylmethyloxycarbonyl-Pro-Lys-PheΨ(PO2CH2)Ala-Pro-Leu-Val, binds to astacin with a Ki value of 42 nM, which is about three orders of magnitude below the corresponding values for previously used hydroxamic acid derivatives. However, the rate constants for association (kon = 96.8 M-1·s-1) and dissociation (koff = 4.1×10-6 s-1) are evidence for the extremely slow binding behaviour of this compound. N-terminally or C-terminally truncated phosphinic analogues of this parent molecule are much less potent, indicating a critical role of the peptide size on the potency. In particular, omission of the N-terminal proline residue leads to a 40-fold increase in Ki which is mostly due to a 75-fold higher koff value. These findings are consistent with the previously solved crystal structure of astacin complexed with one of the phosphinic peptides, benzyloxycarbonyl-Pro-Lys-PheΨ(PO2CH2)Ala-Pro-O-methyl, Ki = 14 µM [Grams, Dive, Yiotakis, Yiallouros, Vassiliou, Zwilling, Bode and Stöcker (1996) Nature Struct. Biol. 3, 671–675]. This structure also reveals that the phosphinic group binds to the active site as a transition-state analogue. The extremely slow binding behaviour of the phosphinic peptides is discussed in the light of the conformational changes involving a unique ‘tyrosine switch ’ in the structure of astacin upon inhibitor binding. The phosphinic peptides may provide a rational basis for the design of drugs directed towards other members of the astacin family which, like bone morphogenetic protein 1 (BMP1; i.e. the procollagen C-proteinase), have become targets of pharmacological research.

Multiplex Analysis of Serum Cytokine Levels in Waldenström Macroglobulinemia Patients.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2616-2616
Author(s):  
Sherine F. Elsawa ◽  
Anne J. Novak ◽  
Steven C. Ziesmer ◽  
Thomas E. Witzig ◽  
Vincent Rajkumar ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
Elevated Serum ◽  
Fold Increase ◽  
Serum Levels ◽  
Healthy Controls ◽  
Β2 Microglobulin ◽  
Healthy Donors ◽  
Cytokine Levels

Abstract Waldenström macroglobulinemia (WM) is a monoclonal B cell disorder characterized by a circulating monoclonal IgM protein that may lead to serum hyperviscosity in association with an infiltration of lymphoplasmacytic cells into the bone marrow. Although proinflammatory and chemotactic cytokines can profoundly affect tumor cells and the tumor microenvironment, and many cytokines have been shown to have potent therapeutic efficacy in preclinical cancer models, the role of cytokine networks in WM is not fully understood. In this study, we used a high-throughput xMAP multiplex immunobead assay technology (Luminex Corp., Austin, TX) to simultaneously test 30 cytokines, chemokines, angiogenic factors as well as growth factors and soluble receptors in the sera of WM patients and compared them with other B cell malignancies including IgM monoclonal gammopathy of undetermined significance (MGUS), follicular lymphoma, chronic lymphocytic leukemia (CLL) as well as healthy controls. Using a Mann-Whitney U test to analyze the differences between the groups, 15 of the 30 cytokines tested had significantly different levels in WM compared to healthy controls. Of those 15 cytokines, 11 were elevated in WM patients and 4 were decreased. Cytokines were grouped into 3 groups; those with &lt; 2-fold difference, 2–8 fold difference and those having &gt; 8-fold difference in their cytokine levels compared to healthy donors. There was a greater than 8-fold increase in the serum levels of Rantes, G-CSF and IL-2R (p&lt;0.0001) in WM patients. Furthermore, 3 cytokines had between 2–8-fold increase in WM patients including IL-4 (p&lt;0.0001), IL-6 (p&lt;0.0019) and IP-10 (p&lt;0.0006). Five cytokines had statistically elevated levels in WM patients compared to healthy controls, however the fold increase was &lt; 2 including HGF (p&lt;0.0185), IL-10 (p&lt;0.0002), MIP-1α (P&lt;0.0484), IL-2 (P&lt;0.0130) and IL-12 (P&lt;0.0155). Of the cytokines that had significantly lower levels in the sera of WM patients, IL-8 (p&lt;0.0001) and EGF (p&lt;0.0001) were &gt; 8-fold decreased, MCP-1 (p&lt;0.0001) was 2–8 fold lower and Eotaxin (p&lt;0.0004) was &lt; 2-fold lower in WM patients. All of the cytokines that had the greatest fold difference (&gt; 8-fold) in WM patients compared to healthy donors also differed significantly from the MGUS patients. Rantes, G-CSF, IL-2R and EGF had significantly different levels compared to other B cell malignancies. We tested for a correlation between the cytokines that had &gt; 2-fold difference between the WM group and control group with clinical features of the disease and found the cytokines IL-6 and IL-2R had a significant correlation with β2-microglobulin levels (p&lt;0.01). We analyzed cytokine levels in the bone marrow plasma of the same patients and found that high levels of IL-2R in the bone marrow microenvironment significantly correlated with anemia and elevated serum β2-microglobulin (p&lt;0.01). In conclusion, we have simultaneously analyzed sera from WM patients for 30 cytokines and found the most significantly elevated cytokines are Rantes, G-CSF and IL-2R and the most significantly downregulated cytokines are IL-8 and EGF. Furthermore, we found that elevated serum levels of IL-6 and IL-2R correlated with β2-microglobulin levels, a measure of disease activity. Further analysis of the biological role of these cytokines in WM may offer insight into disease pathogenesis and provide a basis for novel targeted therapies.

scholarly journals The role of endothelial PI3Kγ activity in neutrophil trafficking

Blood ◽  
2005 ◽  
Vol 106 (1) ◽  
pp. 150-157 ◽  
Author(s):  
Kamal D. Puri ◽  
Teresa A. Doggett ◽  
Ching-Yu Huang ◽  
Jason Douangpanya ◽  
Joel S. Hayflick ◽  
...  
Keyword(s):  
Critical Role ◽  
Fold Increase ◽  
Necrosis Factor Alpha ◽  
Catalytic Subunits ◽  
Injury Model ◽  
Lung Injury Model ◽  
Factor Alpha ◽  
Phosphoinositide 3 Kinase

Phosphoinositide 3-kinase gamma (PI3Kγ) in neutrophils plays a critical role in the directed migration of these cells into inflamed tissues. In this study, we demonstrate the importance of the endothelial component of PI3Kγ activity relative to its leukocyte counterpart in supporting neutrophil interactions with the inflamed vessel wall. Despite the reconstitution of class-Ib PI3K function in neutrophils of p110γ–/– mice, we observed a 45% reduction in accumulation of these cells in an acute lung injury model. Mechanistically, this appears to result from a perturbation in selectin-mediated adhesion as manifested by a 70% reduction in wild-type (WT) neutrophil attachment to and 17-fold increase in rolling velocities on p110γ–/– microvessels in vivo in response to tumor necrosis factor alpha (TNFα). This alteration in adhesion was further augmented by a deficiency in p110δ, suggesting that the activity of both catalytic subunits is required for efficient capture of neutrophils by cytokine-stimulated endothelium. Interestingly, E-selectin–mediated adhesion in p110γ–/– mice was impaired by more than 95%, but no defect in nuclear factor kappa B (NF-κB)–induced gene expression was observed. These findings suggest a previously unrecognized partnership between class-I PI3Ks expressed in leukocytes and endothelium, the combination of which is required for the efficient trafficking of immunocompetent cells to sites of inflammation.

scholarly journals Metabolic profiling reveals that PNPLA3 induces widespread effects on metabolism beyond triacylglycerol remodeling in Huh-7 hepatoma cells

2014 ◽  
Vol 307 (1) ◽  
pp. G66-G76 ◽  
Author(s):  
Hae-Ki Min ◽  
Silvia Sookoian ◽  
Carlos J. Pirola ◽  
Jianfeng Cheng ◽  
Faridoddin Mirshahi ◽  
...  
Keyword(s):  
Liver Disease ◽  
Metabolic Profiling ◽  
Critical Role ◽  
Fold Increase ◽  
Liver Metabolism ◽  
Hepatoma Cells ◽  
Triacylglycerol Lipase ◽  
Nonalcoholic Fatty Liver ◽  
Triglyceride Accumulation

PNPLA3 was recently associated with the susceptibility to nonalcoholic fatty liver disease, a common cause of chronic liver disease characterized by abnormal triglyceride accumulation. Although it is established that PNPLA3 has both triacylglycerol lipase and acylglycerol O-acyltransferase activities, is still unknown whether the gene has any additional role in the modulation of the human liver metabolome. To uncover the functional role of PNPLA3 on liver metabolism, we performed high-throughput metabolic profiling of PNPLA3 siRNA-silencing and overexpression of wild-type and mutant Ile148Met variants (isoleucine/methionine substitution at codon 148) in Huh-7 cells. Metabolomic analysis was performed by using GC/MS and LC/MS platforms. Silencing of PNPLA3 was associated with a global perturbation of Huh-7 hepatoma cells that resembled a catabolic response associated with protein breakdown. A significant decrease in amino- and γ-glutamyl-amino acids and dipeptides and a significant increase in cysteine sulfinic acid, myo-inositol, lysolipids, sphingolipids, and polyunsaturated fatty acids were observed. Overexpression of the PNPLA3 Met148 variant mirrored many of the metabolic changes observed during gene silencing, but in the opposite direction. These findings were replicated by the exploration of canonical pathways associated with PNPLA3 silencing and Met148 overexpression. Overexpression of the PNPLA3 Met148 variant was associated with a 1.75-fold increase in lactic acid, suggesting a shift to anaerobic metabolism and mitochondrial dysfunction. Together, these results suggest a critical role of PNPLA3 in the modulation of liver metabolism beyond its classical participation in triacylglycerol remodeling.

The N-methyl-d-aspartate receptor antagonist MK-801 delays the onset of puberty and may acutely block the first spontaneous LH surge and ovulation in the rat

1991 ◽  
Vol 131 (3) ◽  
pp. 435-441 ◽  
Author(s):  
H. M. A. Meijs-Roelofs ◽  
P. Kramer ◽  
E. C. M. van Leeuwen
Keyword(s):  
Nmda Receptors ◽  
Receptor Antagonist ◽  
Acute Treatment ◽  
Physiological Role ◽  
Female Rat ◽  
Mk 801 ◽  
Aspartate Receptor ◽  
Serum Lh ◽  
Lh Secretion

ABSTRACT The physiological role of activated hypothalamic N-methyl-d-aspartate (NMDA) receptors during the final phase of female sexual maturation was explored in the rat. The effects of administration of the specific non-competitive receptor antagonist MK-801 on the occurrence of first ovulation and on LH secretion were studied. Injections of MK-801 (0·1–0·2 mg/kg body wt, s.c.) were given once or twice daily, starting at 28 or 35 days of age and continuing up to the day of first ovulation, resulted in a significant delay of this ovulation. Rats that were treated daily with 0·2 mg MK-801/kg, starting on days 30 or 34 and continuing up to day 38, but not including the day of first pro-oestrus, also showed retarded first ovulation. No decrease in serum LH concentration, compared with control rats, could be detected in these rats. Acute treatment with MK-801 (one or two injections of 0·2, or one injection of 0·5 mg/kg) given at 11.30 h (and 16.00 h) on the day of first pro-oestrus produced partial (1 × 0·2 mg/kg) or complete (2×0·2 and 1 × 0·5 mg/kg) blockade of first ovulation; blocked rats ovulated 1 day later. Serum LH concentrations at 16.00 h on the day of pro-oestrus were significantly decreased in all MK-801-treated groups compared with saline-injected control rats. At 19.00 and 22.00 h LH concentrations remained low in all non-ovulating MK-801-treated rats, but increased in the MK-801-treated rats that ovulated. Thus chronic blockade of the NMDA receptors by the antagonist MK-801 delays but does not prevent first ovulation, whereas acute treatment blocks the pro-oestrous LH peak. It was concluded that activation of NMDA receptors plays an important role both in tonic and preovulatory LH secretion during the onset of puberty in the female rat. Journal of Endocrinology (1991) 131, 435–441

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