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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine the role of arginine vasopressin (AVP) in stress-induced release of anterior pituitary hormones, AVP antiserum or normal rabbit serum (NRS) was micro-injected into the 3rd ventricle of freely-moving, ovariectomized (OVX) female rats. A single 3 microliter injection was given, and 24 hours later, the injection was repeated 30 min prior to application of ether stress for 1 min. Although AVP antiserum had no effect on basal plasma ACTH concentrations, the elevation of plasma ACTH induced by ether stress was lowered significantly. Plasma LH tended to increase following ether stress but not significantly so; however, plasma LH following stress was significantly lower in the AVP antiserum-treated group than in the group pre-treated with NRS. Ether stress lowered plasma growth hormone (GH) levels and this lowering was slightly but significantly antagonized by AVP antiserum. Ether stress also elevated plasma prolactin (Prl) levels but these changes were not significantly modified by the antiserum. To evaluate any direct action of AVP on pituitary hormone secretion, the peptide was incubated with dispersed anterior pituitary cells for 2 hours. A dose-related release of ACTH occurred in doses ranging from 10 ng (10 p mole)-10 micrograms/tube, but there was no effect of AVP on release of LH. The release of other anterior pituitary hormones was also not affected except for a significant stimulation of TSH release at a high dose of AVP. The results indicate that AVP is involved in induction of ACTH and LH release during stress. The inhibitory action of the AVP antiserum on ACTH release may be mediated intrahypothalamically by blocking the stimulatory action of AVP on corticotropin-releasing factor (CRF) neurons and/or also in part by direct blockade of the stimulatory action of vasopressin on the pituitary. The effects of vasopressin on LH release are presumably brought about by blockade of a stimulatory action of AVP on the LHRH neuronal terminals.
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PMID:Role of arginine vasopressin in control of ACTH and LH release during stress. 298 9

Mouse hybrid cell clones secreting antigonadotropin releasing hormone monoclonal antibody were developed by fusion of SP2/O-Ag 1.4 myeloma cells with splenocytes of mouse immunized with gonadotropin releasing hormone (GnRH) tagged to tetanus toxoid. The product of hybrid cell clones obtained as ascites fluid from mouse peritoneal cavity had a titre of 10(6) (30-40% binding of 125I-GnRH) in radioimmunoassay. The antibody was IgG2a and Kappa. The association constant (Ka) of the product of hybrid cell clone P(8)16(62) for binding with GnRH was 1.2 X 10(9) L/mole. The monoclonal antibody (P(8)16(62)) was highly specific for the native GnRH and devoid of reactivity with thyroid releasing hormone as tested in competitive radioimmunoassay. The recognition for GnRH agonists by monoclonal was 387-fold less with D-Ser (But)6 des Gly10 GnRH ethylamide and 608-fold less with Bz1-His6 GnRH. Monoclonal anti-GnRH antibody was competent to neutralize the in vivo bioactivity of the hormone as evident by the block of estrus cycle and termination of pregnancy in mice. Termination of pregnancy in animals receiving anti-GnRH monoclonal could be prevented by administration of progesterone.
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PMID:Characteristics and bioefficacy of monoclonal antigonadotropin releasing hormone antibody. 388 52

The complete synthesis of the C-terminal 28 residues segment 67-94 of human seminal plasma beta-Inhibin, called beta 2-Inhibin, is reported. The Inhibin-like activity of the native 94 amino acids beta-Inhibin is compared to that of the synthetic replica of beta 2-Inhibin. In all assays used both peptides effectively suppress the FSH release induced by LHRH but have little effect on the LH release. In the mouse both peptides are equipotent on a mole basis. In the rat the synthetic beta 2-Inhibin is 3-10 times more potent than beta-Inhibin. Both peptides are active in rat anterior pituitary primary culture assays where maximum suppression of FSH release induced by LHRH occurs around 300 pmol/ml of beta 2-Inhibin. In contrast, maximum suppression of FSH release in the mouse pituitary assay occurs at 10-15 pmol/ml of either Inhibin.
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PMID:beta 2-Inhibin contains the active core of human seminal plasma beta-inhibin: synthesis and bioactivity. 391 87

The Helmholtz free energy F (rather than the energy) is the correct criterion for stability; therefore, calculation of F is important for peptides and proteins that can populate a large number of metastable states. The local states (LS) method proposed by H. Meirovitch [(1977) Chemical Physics Letters, Vol. 45, p. 389] enables one to obtain upper and lower bounds of the conformational free energy, FB (b,l) and FA (b,l), respectively, from molecular dynamics (MD) or Monte Carlo samples. The correlation parameter b is the number of consecutive dihedral or valence angles along the chain that are taken into account explicitly. The continuum angles are approximated by a discretization parameter l; the larger are b and l, the better the approximations; while FA can be estimated efficiently, it is more difficult to estimate FB. The method is further developed here by applying it to MD trajectories of a relatively large molecule (188 atoms), the potent "Asp4-Dpr10" antagonist [cyclo(4/10)-(Ac-delta 3Pro1-D-pFPhe2-D-Trp3-Asp4-Tyr5-D-Nal6-Leu7-Arg8 -Pro9- Dpr10-NH2)] of gonadotropin releasing hormone (GnRH). The molecule was simulated in vacuo at T = 300 K in two conformational states, previously investigated [J. Rizo et al. Journal of the American Chemical Society, (1992) Vol. 114, p. 2860], which differ by the orientation of the N-terminal tail, above (tail up, TU) and below (tail down, TD) the cyclic heptapeptide ring. As in previous applications of the LS method, we have found the following: (1) While FA is a crude approximation for the correct F, results for the difference, delta FA = FA (TD)-FA (TU) converge rapidly to 5.6 (1) kcal/mole as the approximation is improved (i.e., as b and l are increased), which suggests that this is the correct value for delta F; therefore TD is more stable than TU. (The corresponding difference in entropy, T delta SA = 1.3(2) kcal/mole, is equal to the value obtained by the harmonic approximation.) (2) The lowest approximation, which has the minimal number of local states, i.e., based on b = 0 (no correlations) and l = 1 (the angle values are distributed homogeneously), also leads to the correct value of delta F, within the error bars. This is important since the lowest approximation can be applied even to large proteins. (3) The method enables one to define the entropy of a part of the molecule and thus to measure the flexibility of this part.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Computer simulation of the free energy of peptides with the local states method: analogues of gonadotropin releasing hormone in the random coil and stable states. 805 67

The precursor of gonadotropin-releasing hormone (GnRH) and the 56-amino acid GnRH-associated peptide is encoded in an mRNA of about 560 bases in length. This mRNA derives from an approximately 4300-base pair-long gene consisting of four relatively short exons (denoted 1, 2, 3, and 4) and three large introns (A, B, and C). In this study, we characterized the order by which the three introns are spliced from the primary transcript and processing intermediates to give rise to a mature mRNA and evaluated the potential role of gene transcription and pre-mRNA processing in the control of proGnRH mRNA levels in vivo. Nuclear and cytoplasmic RNA fractions isolated from rat preoptic area-anterior hypothalamus (POA-AH) and basal olfactory area (located rostral to the POA) were analyzed by 1) solution hybridization-RNase protection mapping using several RNA probes directed at various regions of the proGnRH gene and 2) reverse transcription-polymerase chain reaction using several oligonucleotide primers. Both types of analysis showed that proGnRH pre-mRNA processing begins with the splicing of intron B from the primary gene transcript. Hence, intron B is the ideal target for studying proGnRH primary transcript by in situ hybridization. Subsequent splicing of introns A and C appeared to take place in two alternative, although not equally prevalent pathways. Quantitative analysis indicated that the proGnRH hnRNA species constituted, on a mole basis, about 20% of the total gene transcripts in the POA-AH. The primary transcript alone constituted about 10% of the total gene transcripts in the POA-AH and as much as 20% in the basal olfactory area. The prospect of blockade of proGnRH hnRNA processing by means of hybridization with endogenous antisense RNAs (transcribed from the SH gene on the opposite strand of the same DNA locus) did not prove to be likely, as the SH transcripts were present at very low levels compared to any of the proGnRH RNA species. We conclude that the relatively large pool of proGnRH hnRNA may reflect a high rate of gene transcription and/or slow RNA processing.
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PMID:Processing of gonadotropin-releasing hormone gene transcripts in the rat brain. 830 66

The epidermal nevus syndrome is characterized by the association of epidermal nevi with abnormalities of the skin, skeletal system, central nervous system, eyes, and cardiovascular system, as well as with malignant conditions. We describe a 2-year-old girl with an extensive epidermal nevus involving the left side of the body (nevus unius lateris) and associated with a woolly hair nevus on the left parietal area of the scalp and multiple acquired melanocytic nevi. Idiopathic central precocious puberty characterized by premature breast and public hair development and advanced bone age developed at the age of 20 months. A sharp increase in serum gonadotropins after a luteinizing hormone releasing hormone (LHRH) stimulation test confirmed the presence of central precocious puberty. This is the third reported case of precocious puberty associated with the epidermal nevus syndrome.
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PMID:Epidermal nevus syndrome: association with central precocious puberty and woolly hair nevus. 891

The Mashona mole-rat, Cryptomys darlingi, exhibits an extreme reproductive division of labour. Reproduction in the colony is restricted to a single breeding pair. The non-reproductive male and female colony members are restrained from sexual activity by being familiar and related to one another and the reproductive animals. Circulating basal concentrations of luteinizing hormone (LH) as well as LH levels measured in response to a single exogenous gonadotropin releasing hormone (GnRH) challenge are not significantly different between the reproductive and non-reproductive groups of either sex. Socially induced infertility in both non-reproductive males and females does not result from a reduced pituitary secretion of LH or decreased sensitivity to hypothalamic GnRH, but rather appears to result from an inhibition of reproductive behaviour in these obligate outbreeders. The African mole-rats exhibit a continuum of socially induced infertility with differing social species inhabiting regions of varying degrees of aridity. In this continuum a transition from a predominantly behavioural repression in a social mesic-adapted species through to complete physiological suppression lacking incest avoidance in an arid-adapted eusocial species occurs in this endemic African family of rodents.
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PMID:LH responses to single doses of exogenous GnRH by social Mashona mole-rats: a continuum of socially induced infertility in the family Bathyergidae. 926 67

A paired terminal nerve with gonadotropin-releasing hormone-immunoreactive (GnRHir) neurons was found in five of six specimens of the Zambian common mole-rat (Cryptomys sp.). In these animals the distribution of GnRHir neurons in the CNS was approximately even on both sides. One adult female lacked a right terminal nerve, yet exhibited a comparable total number of GnRHir neurons, most of which were located on the left side of the brain, i. e., on that side where the terminal nerve was present. An additional population of GnRHir cells was detected in the area of the parafascicular and dorsomedial thalamic nuclei of three non-reproductive adult females, but not in young animals (one female, two males). The additional GnRHir cells, referred to as dark spot cells (DSCs) since their perikarya exhibit large or small strongly immunoreactive vacuoles, were present on both sides of the brain in equal numbers even in the specimen with unilateral absence of the terminal nerve. Obviously, the lack of one terminal nerve correlates with a drastic reduction in the number of ipsilateral genuine neurons but leaves the DSCs unaffected.
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PMID:Unilateral absence of the terminal nerve and distribution of gonadotropin-releasing hormone immunoreactive neurons in the brain of the common mole-rat (Cryptomys, Rodentia). 983 32

The influence of endogenous opioid peptides (EOPs) on plasma luteinizing hormone (LH) levels in subordinate female highveld mole-rats (Cryptomys hottentotus pretoriae) was investigated to elucidate the physiological mechanisms responsible for inhibiting their gonadotropin-releasing hormone (GnRH) and/or LH release. The opioid antagonist naloxone was administered either alone or with GnRH. A single injection of naloxone failed to alter plasma LH levels in dominant reproductive females or in subordinate non-reproductive females in the presence or absence of their ovaries. Pituitary sensitivity to a GnRH challenge was not influenced by naloxone administered acutely or according to longer-term regimens in any of the treatment groups. The results suggest no role for EOPs at the level of the pituitary or hypothalamus in the socially induced infertility evident in non-reproductive female highveld mole-rats.
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PMID:Reproductive suppression in subordinate female highveld mole-rats (Cryptomys hottentotus pretoriae): no role for endogenous opioid peptides. 1657 70

The Damaraland mole-rat (Fukomys damarensis) is a eusocial, subterranean rodent, in which breeding is limited to a single reproductive pair within each colony. Non-reproductive females, while in the confines of the colony, exhibit socially induced infertility. Anovulation is thought to be caused by a disruption in the normal gonadotropin-releasing hormone (GNRH) secretion from the hypothalamus. To assess whether social suppression is associated with altered Gnrh mRNA expression in the brain, we investigated the distribution and gene expression levels by means of in situ hybridization in female breeders and non-breeders from field captured colonies of the Damaraland mole-rat. We found expression of Gnrh mRNA as a loose network in several forebrain areas of female Damaraland mole-rats with the majority of labelling in the preoptic and anterior hypothalamus. The distribution matched previous findings using immunocytochemistry in this and other social mole-rat species. Quantification of the hybridisation signal revealed no difference between breeding and non-breeding females in the average optical density of the hybridization signal and the size of the total area covered by Gnrh mRNA. However, analysis along the rostro-caudal axis revealed significantly elevated Gnrh mRNA expression in the rostral preoptic region of breeders compared to non-breeders, whereas the latter had increased Gnrh mRNA expression at the caudal level of the anterior hypothalamus. This study indicates that social suppression affects the expression of Gnrh mRNA in female Damaraland mole-rats. Furthermore, differential regulation occurs within different neuron subpopulations.
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PMID:Gnrh mRNA expression in the brain of cooperatively breeding female Damaraland mole-rats. 2810 24


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