Showing papers by "Rockefeller University published in 1980"
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TL;DR: In this paper, the authors make a connection between the mind-body problem and the so-called "identity thesis" in analytic philosophy, which has wide-ranging implications for other problems in philosophy that traditionally might be thought far-removed.
Abstract: I hope that some people see some connection between the two topics in the title. If not, anyway, such connections will be developed in the course of these talks. Furthermore, because of the use of tools involving reference and necessity in analytic philosophy today, our views on these topics really have wide-ranging implications for other problems in philosophy that traditionally might be thought far-removed, like arguments over the mind-body problem or the so-called ‘identity thesis’. Materialism, in this form, often now gets involved in very intricate ways in questions about what is necessary or contingent in identity of properties — questions like that. So, it is really very important to philosophers who may want to work in many domains to get clear about these concepts. Maybe I will say something about the mind-body problem in the course of these talks. I want to talk also at some point (I don’t know if I can get it in) about substances and natural kinds.
5,988 citations
TL;DR: A cell contains millions of protein molecules, which are continually being synthesized and degraded, and at homeostasis, a given species of protein is represented by a characteristic number of molecules that is kept constant within a narrow range.
Abstract: Concurrently with or shortly after their synthesis on ribosomes, numerous specific proteins are unidirectionally translocated across or asymmetrically integrated into distinct cellular membranes. Thereafter, subpopulations of these proteins need to be sorted from each other and routed for export or targeted to other intracellular membranes or compartments. It is hypothesized here that the information for these processes, termed “protein topogenesis,” is encoded in discrete “topogenic” sequences that constitute a permanent or transient part of the polypeptide chain. The repertoire of distinct topogenic sequences is predicted to be relatively small because many different proteins would be topologically equivalent—i.e., targeted to the same intracellular address. The information content of topogenic sequences would be decoded and processed by distinct effectors. Four types of topogenic sequences could be distinguished: signal sequences, stop-transfer sequences, sorting sequences, and insertion sequences. Signal sequences initiate translocation of proteins across specific membranes. They would be decoded and processed by protein translocators that, by virtue of their signal sequence-specific domain and their unique location in distinct cellular membranes, effect unidirectional translocation of proteins across specific cellular membranes. Stop-transfer sequences interrupt the translocation process that was previously initiated by a signal sequence and, by excluding a distinct segment of the polypeptide chain from translocation, yield asymmetric integration of proteins into translocation-competent membranes. Sorting sequences would act as determinants for posttranslocational traffic of subpopulations of proteins, originating in translocation-competent donor membranes (and compartments) and going to translocation-incompetent receiver membranes (and compartments). Finally, insertion sequences initiate unilateral integration of proteins into the lipid bilayer without the mediation of a distinct protein effector. Examples are given for topogenic sequences, either alone or in combination, to provide the information for the location of proteins in any of the intracellular compartments or for the asymmetric orientation of proteins and their location in any of the cellular membranes. Proposals are made concerning the evolution of topogenic sequences and the relationship of protein topogenesis to the precellular evolution of membranes and compartments.
1,199 citations
TL;DR: Recordings of the alarms played back when predators were absent caused Vervet monkeys to run into trees for leopard alarms, look up for eagle alarms, and look down for snake alarms.
Abstract: Vervet monkeys give different alarm calls to different predators. Recordings of the alarms played back when predators were absent caused the monkeys to run into trees for leopard alarms, look up for eagle alarms, and look down for snake alarms. Adults call primarily to leopards, martial eagles, and pythons, but infants give leopard alarms to various mammals, eagle alarms to many birds, and snake alarms to various snakelike objects. Predator classification improves with age and experience.
1,186 citations
TL;DR: It is demonstrated by immunofluorescence microscopy that the lamina is reversibly disassembled during cell division, coincident with the disassembly and reconstruction of the mitotic nuclear envelope architecture, and that all three lamins are monomeric at periods of mitotic lamina disassembly.
902 citations
TL;DR: It is concluded that vervet alarm calls function to designate different classes of external danger, and context was not a systematic determinant of response.
876 citations
TL;DR: The role of the PSD and of some of its proteins in these synaptic responses is discussed and it is possible that PSDs isolated from cerebrum and midbrain were derived from the Gray type I, or asymmetric, synapses, whereas cerebellum PSDs werederived from theGray type II, or symmetric,synapses.
Abstract: Postsynaptic densities (PSDs) have been isolated from cerebral cortex, midbrain, cerebellum, and brain stem by the Triton X-100 method previously used in the isolation of cerebral PSDs (Cohen et al., 1977, J. Cell Biol. 74:181). These PSDs have been compared in protein composition, protein phosphorylation, and morphology. Thin-section electron microscopy revealed that cerebral cortex and midbrain PSDs were identical, being approximately 57 nm thick and composed of apparent aggregates 20-30 nm in diameter. Isolated cerebellar PSDs appeared thinner (33 nm) than cerebral cortex PSDs and lacked the apparent 20- to 30-nm aggregates, but had a latticelike structure. In unidirectional and rotary-shadowed replicas, the cerebrum and midbrain PSDs were circular in shape with a large central perforation or hole in the center of them. Cerebellum PSDs did not have a large perforation, but did have numerous smaller perforations in a lattice like structure. Filaments (6-9 nm) were observed connecting possible 20- to 30-nm aggregates in cerebrum PSDs and were also observed radiating from one side of the PSD. Both cerebral cortex and midbrain PSDs exhibited identical protein patterns on SDS gel electrophoresis. In comparison, cerebellar PSDs (a) lacked the major 51,000 Mr protein, (b) contained two times less calmodulin, and (c) contained a unique protein at 73,000 Mr. Calcium plus calmodulin stimulated the phosphorylation of the 51,000 and 62,000 Mr bands in both cerebral cortex and midbrain PSDs. In cerebellar PSDs, only the 58,000 and 62,000 Mr bands were phosphorylated. In the PSDs from all brain regions, cAMP stimulated the phosphorylation of Protein Ia (73,000 Mr), Protein Ib (68.000 Mr), and a 60,000 Mr protein, although cerebrum and midbrain PSDs contained very much higher levels of phosphorylated protein than did the cerebellum. On the basis of the morphological criteria, it is possible that PSDs isolated from cerebrum and midbrain were derived from the Gray type I, or asymmetric, synapses, whereas cerebellum PSDs were derived from the Gray type II, or symmetric, synapses. Since there is some evidence that the type I synapses are involved in excitatory mechanisms while the type II are involved in inhibitory mechanisms, the role of the PSD and of some of its proteins in these synaptic responses is discussed.
738 citations
TL;DR: The cell type generated by retinoic acid and dibutyryl cAMP treatment is therefore indistinguishable from definitive parietal endoderm, and analysis of the final phenotype indicates that it is not dependent upon the continued presence of either compound, and that cAMP agents are active only on cells that have been treated with retinoi acid.
711 citations
TL;DR: A review of the principal features of DC that are useful in their identification, purification, and differentiation from mononuclear phagocytes, the other cell type most often considered in studies of accessory cell functions, and properties of DC in situ are considered.
Abstract: Dendritic cells (DC) are irregularly shaped cells that were initially identified in the glass and plastic adherent population of mouse spleen. DC are la*, Ig", thy-1" bone marrow derived elements that show little or no endocytic activity for several tracers. DC occur in low frequency accounting for less than 1 *% of the cells in all organs we have studied. However, methods have been developed for their enrichment. DC in small numbers stimulate allogeneic and syngeneic mixed leukocyte reactions (MLR) and serve as accessory cells for the development of in viiro immune responses. This review will consider several topics: a) the principal features of DC that are useful in their identification, purification, and differentiation from mononuclear phagocytes the other cell type most often considered in studies of accessory cell functions; b) surface markers of DC including expression of la antigens; c) properties of DC in situ; and d) functional capacities of DC in vitro.
554 citations
TL;DR: Serial sectioning indicated that tubular structures in Golgi-lysosome regions were often interconnected to the larger vesicles, but that tubules in the peripheral cytoplasm were only occasionally connected to larger structures.
459 citations
TL;DR: It is demonstrated that a portion of this highly conserved segment of repetitive mamalian DNA sequence is similar to a sequence found within a low molecular weight RNA that hydrogen-bonds to poly(A)-terminated RNA molecules of Chinese hamsters and a sequence that forms half of a perfect inverted repeat near the origin of DNA replication in papovaviruses.
Abstract: DNA base sequence comparisons demonstrate that the principal family of 300-nucleotide interspersed human DNA sequences, the repetitive double-strand regions of HeLa cell heterogeneous nuclear RNA, and specific RNA polymerase III in vitro transcripts of cloned human DNA sequences are all representatives of a closely related family of sequences. A segment of approximately 30 residues of these sequences is highly conserved in mammalian evolution because it is also present in the interspersed repeated DNA sequences of Chinese hamsters. Further DNA sequence comparisons demonstrate that a portion of this highly conserved segment of repetitive mamalian DNA sequence is similar to a sequence found within a low molecular weight RNA that hydrogen-bonds to poly(A)-terminated RNA molecules of Chinese hamsters and a sequence that forms half of a perfect inverted repeat near the origin of DNA replication in papovaviruses.
458 citations
TL;DR: In this article, a group of free-ranging juvenile vervet monkeys were played to a group containing their mothers and two "control" females who also had offspring in the group.
TL;DR: The projections of the nucleus of the solitary tract were studied by autoradiographic anterograde fiber‐tracing and horseradish peroxidase (HRP) retrograde cell‐labeling and showed topographically organized bilateral projections to the ventrolateral medullary reticular formation which contains neurons of the ambiguus complex.
Abstract: The projections of the nucleus of the solitary tract (NST) were studied by autoradiographic anterograde fiber-tracing and horseradish peroxidase (HRP) retrograde cell-labeling. Tritiated proline and leucine were deposited in electrophysiologically identified regions of NST. Injections of NST at levels caudal to where the vagus enters the nucleus, from which responses were evoked by stimulation of cranial nerves IX and X, revealed topographically organized bilateral projections to, most prominently, the ventrolateral medullary reticular formation which contains neurons of the ambiguus complex, and to the lateral and medial parabrachial nuclei, including a small portion of the medially adjacent central gray substance. Labeled fibers in the ventrolateral reticular formation were present from the nucleus retroambigualis rostralward to the retrofacial nucleus, with the densest concentration located over the nucleus ambiguus proper. The parabrachial projection was confirmed using HRP and shown to originate from cells in the medial subdivision of NST. Due to the problem of fibers en passant, it was not possible to interpret conclusively the cell-labeling seen around the solitary tract after HRP injections made in the region of the nucleus ambiguus. Labeled fibers were also traced from caudal NST to the dorsal motor nucleus of the vagus, but their origin could not be determined with certainty. Other labeled axons, traced to circumscribed parts of the inferior olivary complex and via the contralateral medial lemniscus to VPL of the thalamus, were shown in HRP experiments to originate from the dorsal column nuclei rather than NST. No labeled fibers were traced into the spinal cord, nor were any cells labeled in NST after large HRP deposits in upper cervical segments. Isotope deposits at levels of NST rostral to the entrance of the vagus, from which responses were evoked by rapid stimulation of the tongue, revealed an ipsilateral projection which ascends as a component of the central tegmental tract to the parvicellular part of the ventral posteromedial thalamic nucleus (VPMpc). After small HRP deposits in VPMpc, labeled cells in NST were restricted to the rostral part of the lateral subdivision. No labeled axons were traced from rostral NST to the ambiguus complex or parabrachial area. Injections of 3H-amino acids at intermediate levels of NST resulted in fiber-labeling in VPMpc, the parabrachial area, and the ambiguus complex.
TL;DR: A method of finding pattern similarities between two sequences, where two portions, one from each sequence, are similar if they are close in the metric space of evolutionary distances, lends itself to finding similarities by computer between pairs of biological sequences.
TL;DR: Two vocal control nuclei of the canary telencephalon, hyperstriatum ventrale, pars caudale (HVc) and nucleus robustus archistriatalis (RA), are larger in males, that learn complex songs, than in females, that normally do not sing.
TL;DR: In this article, grooming and related behaviors among adult females in three groups of vervet monkeys were studied for 14 months, and the authors found that high rates of grooming were significantly correlated with high levels of alliance formation and/or proximity.
TL;DR: The results suggest that the oligopeptides competitively interfere with the N-terminal region of the F 1 or HA 2 polypeptides of paramyxoviruses or myxoviruse, respectively, providing a possible new approach to chemical inhibition of viral replication.
TL;DR: In relation to the actions of progesterone which do and do not require estrogen priming and in relation to intracranial progestone implantation studies, the properties of these sites appear indistinguishable from those of cytoplasmic progestin receptors from the uterus.
Abstract: Putative progestin receptors have been characterized in brain and pituitary tissue from untreated and estrogenprimed ovariectomized-adrenalectomized rats. The properties of these sites appear indistinguishable from those of cytoplasmic progestin receptors from the uterus: 1) sedimentation coefficient of 7S, which is reduced by half in the presence of 0.3 m KC1; 2) specificity of binding which strongly favors synthetic and natural progestins as opposed to glucocorticoids, androgens, and estrogens; 3) a dissociation constant for binding the synthetic progestin [3H]R5020 (17α,21-dimethyl-19-norpregna-4, 9-diene-3,20- dione) of 0.3 nm; and 4) similar rates of formation and dissociation of the [3H]R5020-receptor complexes. In these respects, the estrogen-inducible and noninducible receptors of the brain also appear to be indistinguishable from each other. Estrogen induction of progestin receptors is apparent in uterus (6-fold), pituitary (8-fold), mediobasal hypothalamus (4-fold), and preoptic area (4-fold), a...
TL;DR: The chapter emphasizes micro-geographical variation, and examines the two factors that most significantly influence local spatial variation in bird song: the extent and accuracy of imitation, and the site of song imitation with respect to the sites of breeding.
Abstract: Publisher Summary This chapter deals with repertoires and geographical variation in bird song Three methods have been used to investigate the function of a behavior pattern: (1) interspecific comparisons in which differences between species are related to ecological and life history variables; (2) intraspecific comparisons relating variations between individuals to variations in survival, reproductive success, or success in acquiring resources; and (3) direct experimental tests of the effect of a behavior All three methods have been applied to the study of how selection favors repertoires The chapter emphasizes micro-geographical variation, and examines the two factors that most significantly influence local spatial variation in bird song: (1) the extent and accuracy of imitation, and (2) the site of song imitation with respect to the site of breeding It discusses the relationship between genetic separation of populations and song variations, and the influence of song repertoire size on the ability to establish or maintain sharp discontinuities in song traditions between neighboring populations The usefulness and definition of the term “dialect” and the functional significance of vocal imitation and its influence on song dialects are also discussed
TL;DR: The F Glycoprotein 43 Protease activation mutants of a paramyxovirus 45 The activating protease 45 Proteolytic cleavage and viral virulence ..... 46 structure of the F protein 47 Specific inhibition of virus-induced membrane fusion and virus penetration by oligopeptides 48 Importance of antibodies to F glycoprotein in prevention of spread of paramyxvirus infection 49
Abstract: The F Glycoprotein 43 Protease activation mutants of a paramyxovirus 45 The activating protease 45 Proteolytic cleavage and viral virulence ..... 46 Structure of the F protein 47 Specific inhibition of virus-induced membrane fusion and virus penetration by oligopeptides 48 Importance of antibodies to F glycoprotein in prevention of spread of paramyxovirus infection 49
TL;DR: A hypoxanthine phosphoribosyl transferase (HPRT)-deficient human B-cell line derived from a patient suffering from multiple myeloma with peripheral lymphocytes obtained from a patients with subacute sclerosing panencephalitis were found to secrete human IgM specific for measles virus nucleocapsids.
Abstract: Monoclonal antibodies against a variety of antigens can be produced using techniques of somatic cell hybridization between cells of rodent myeloma lines and B cells derived from animals immunized against a given antigen. However, because of the monoclonal antibodies secreted by these hybridomas are of rodent origin, their use in human immunotherapy is limited. Thus the production of B-cell hybrids that secrete human monoclonal antibodies may be of considerable value. We have hybridized a hypoxanthine phosphoribosyl transferase (HPRT)-deficient human B-cell line derived from a patient suffering from multiple myeloma with peripheral lymphocytes obtained from a patient with subacute sclerosing panencephalitis (SSPE). These hybridomas were found to secrete human IgM specific for measles virus nucleocapsids.
TL;DR: It is found that the weak radiative corrections to $\ensuremath{
u}$-hadron neutral-current scattering give rise to a universal renormalization factor, which is useful in the study of radiative Corrections to many other processes of physical interest.
Abstract: Weak corrections of order $\ensuremath{\alpha}$ to $\ensuremath{
u}$-induced neutral-current phenomena are studied in the $\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ theory. Calculations are carried out using a simple renormalization framework in which ${cos\ensuremath{\theta}}_{W}=\frac{{m}_{W}}{{m}_{z}}$ exactly and amplitudes are expressed in terms of ${G}_{\ensuremath{\mu}}$, the universal constant of the weak interactions obtained from muon decay. To rigorously evaluate corrections to hadronic vertices, we employ the current-algebra formulation of radiative corrections. Our main emphasis is on large-momentum-transfer processes such as deep-inelastic scattering; however, we also discuss low-momentum transfers and $\ensuremath{
u}$-lepton interactions. We find that the weak radiative corrections to $\ensuremath{
u}$-hadron neutral-current scattering give rise to a universal renormalization factor ${\ensuremath{\rho}}_{\mathrm{Nc}}^{(\ensuremath{
u};h)}$ multiplying the overall amplitude, a correction factor ${\ensuremath{\kappa}}^{(\ensuremath{
u};h)}({q}^{2})$ multiplying ${{sin}^{2}\ensuremath{\theta}}_{W}$, and two new induced currents not present at the tree level. For nonexotic values of ${m}_{{\ensuremath{\varphi}}_{1}}$ (Higgs-scalar mass) and ${m}_{t}$ $t$-quark mass), the corrections ${\ensuremath{\rho}}_{\mathrm{Nc}}^{(\ensuremath{
u};h)}$- 1 and ${\ensuremath{\kappa}}^{(\ensuremath{
u};h)}({q}^{2})$- 1 turn out to be small over a wide range of momentum transfers. The smallness of these corrections is mainly due to the renormalization framework employed; but it is helped by a subtle partial cancellation between hadronic and bosonic contributions. Photonic corrections to the hadronic vertices are also briefly discussed in the leading-logarithm approximation of the quark-parton model. Detailed expressions for the $\mathrm{ZZ}$, $\mathrm{WW}$, $\ensuremath{\gamma}Z$, and $\ensuremath{\gamma}\ensuremath{\gamma}$ self-energies along with a discussion of the effect of large ${m}_{t}$ on these quantities are given. They play an important role in our renormalization scheme and are useful in the study of radiative corrections to many other processes of physical interest.
TL;DR: The complete sequence of cloned full-length DNA (NS DNA) derived from influenza virus gene 8, which codes for two unique polypeptides, NS1 and NS2, and the sequence of the NS2 mRNA is obtained, indicating that NS1and NS2 overlap by 70 amino acids that are translated from different reading frames.
TL;DR: Additional data on mature leaf petioles and young leaves suggest that the high ratio of cell-sap to cell-wall in these items, and their related high digestibility, explain the high relative abundance of these items in the P. johnii diet.
Abstract: The leaf-monkey Presbytis johnii has been found to exhibit considerable selectivity in its dietary utilization of mature foliage in a rain-forest habitat. To investigate the basis of this selectivity and to examine the hypothesis that the observed selection is related to the digestibility and toxicity of the available foliage, chemical analyses have been made on 16 of the most important tree species in the monkey's habitat. It has been found that the most heavily used items, which form a staple part of the diet of P. johnii, are characterized by a low fibre content and a very low condensed tannin content. However, neither class of compound is an absolute feeding deterrent as minor, but still significant, mature leaf food items contain considerable amounts of both. It is suggested that the feeding deterrents in these minor items, which may be ingested to supply specific dietary requirements, can perhaps be tolerated because of their dilution in the gut by the dietary staples. An examination of the pepsin/cellulase digestibility of available mature foliage showed that the staple food items tended to be highly digestible. Little correlation has been found between alkaloid content and food selection and it is suggested that the colobine forestomach microflora has the ability to detoxify at least some alkaloids. Additional data on mature leaf petioles and young leaves suggest that the high ratio of cell-sap to cell-wall in these items, and their related high digestibility, explain the high relative abundance of these items in the P. johnii diet.
TL;DR: In this article, the authors considered the ℏ→0 limit of the quantum dynamics generated by the Hamiltonian and proved that the evolution of certain Gaussian states is determined asymptotically as ℎ→0 by classical mechanics.
Abstract: We consider the ℏ→0 limit of the quantum dynamics generated by the HamiltonianH(ℏ)=−(ℏ2/2m)Δ+V We prove that the evolution of certain Gaussian states is determined asymptotically as ℏ→0 by classical mechanics For suitable potentialsV inn≧3 dimensions, our estimates are uniform in time and our results hold for scattering theory
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TL;DR: The association of certain Ia antigens with susceptibility or resistance to a variety of diseases, including rheumatoid arthritis, systemic lupus erythematosus, idiopathic thrombocytopenic purpura, rheumatic fever, multiple sclerosis, and diabetes, provides both a valuable clinical predictive measure and a lead for the future study of pathogenetic factors possibly related to the particular Ia genes involved.
Abstract: Publisher Summary This chapter discusses conceptual and technical developments in the field of human Ia antigens by describing the chemical structure and immunologic relationship to their murine counterparts. The distribution of human Ia antigens is limited primarily to the B lymphocyte series, stimulated T cells, and stem and precursor hematopoietic cells, suggestive of both cell type and differentiation specificity. The association of certain Ia antigens with susceptibility or resistance to a variety of diseases, including rheumatoid arthritis, systemic lupus erythematosus, idiopathic thrombocytopenic purpura, rheumatic fever, multiple sclerosis, and diabetes, provides both a valuable clinical predictive measure and a lead for the future study of pathogenetic factors possibly related to the particular Ia genes involved. The chapter examines the Ia antigens from two principal perspectives: (1) as membrane components related to differentiation, and (2) as part of a genetically intricate system of molecules bearing alloantigens that have relevance to susceptibility to certain diseases. Three types of antisera are used to detect Ia antigens: alloantisera, heteroantisera raised in rabbits or similar species, and monoclonal hybridoma reagents. It is apparent that the relationship of diseases to the Ia alloantigens is an intricate one and is likely to involve several distinct factors.
TL;DR: The location of central neurons that contribute preganglionic parasympathetic axons to cranial nerves VII, IX, and X in rats has been identified using horseradish peroxidase (HRP) tracting methods.
Abstract: The location of central neurons that contribute preganglionic parasympathetic axons to cranial nerves VII, IX, and X in rats has been identified using horseradish peroxidase (HRP) tracing methods. Collectively, these neurons form an uninterrupted dorsal column that extends over the entire length of the medulla. The cephalic end of this column turns ventrally with neurons scattered in the parvicellular reticular formation between the rostral pole of the nucleus of the solitary tract (NST) and the facial motor nucleus. Applying HRP crystals to the cut cervical vagus labels neurons in the classically defined dorsal motor nucleus. Rostrally, this distribution continues along the medial edge of NST, ending just caudal to neurons exiting in the lingual-tonsilar branch of IX. At the rostral pole of the NST and ventral to it, neurons occur that serve the lingual-tonsilar and tympanic branches of IX, as well as the chorda tympani and greater superficial petrosal (GSP) branches of VII. Central neurons of the chorda tympani and tympanic nerves spread ventrally from NST into a sparse but largely coextensive distribution in the reticular formation lateral to the ascending radiations of the facial motor nucleus. Immediately ventral to this distribution, a dense accumulation of GSP efferent neurons appears rostrolateral to the facial motor nucleus. Although they vary considerably in number and packing density, the neurons of the dorsal efferent column and those extending from it into the reticular formation have similar morphological characteristics. The somata are medium-sized, fusiform, or multipolar, but with usually no more than five or six major processes.
TL;DR: It is concluded that the hypertriglyceridemia associated with T. brucei infection in rabbits results predominantly from a defect in triglyceride degradation.
TL;DR: Infusion of exogenous LH- RH in the CG had an immediate facilitative effect on the lordosis reflex, whereas passive immunisation against endogenous LH-RH by anti-LH-RH γ-globulin diminished the reflex.
Abstract: The lordosis reflex, which characterises female reproductive behaviour in rodents, can be potentiated in oestrogen-primed ovariectomised female rats by electrical stimulation of the ventromedial nucleus of the hypothalamus (VMN). Subsequent demonstration of an immediate and large facilitation of the lordosis reflex from the mesencephalic central grey (CG) prompted us to speculate that the VMN may exert an oestrogen-dependent tonic bias on the mesencephalic circuitry for lordosis via its heavy descending projections. Moreover, we considered that luteinising hormone-releasing hormone (LH-RH) could be involved in this system. LH-RH can potentiate lordosis when given systemically to oestrogen-primed ovariectomised rats, and neurotropic effects of this peptide have been shown by microiontophoresis. Also, some axons in the CG have been stained with antiserum to LH-RH. The present study examined a possible role of LH-RH in the CG in the regulation of the lordosis reflex of oestrogen-primed ovariectomised female rats. Infusion of exogenous LH-RH in the CG had an immediate facilitative effect on the lordosis reflex, whereas passive immunisation against endogenous LH-RH by anti-LH-RH gamma-globulin diminished the reflex.
TL;DR: In this study, the temporal relationship between inducible progestin receptors in both MBH-POA and pituitary and the time course of estrogen activation of mating behavior is explored.
Abstract: 17β-Estradiol has been shown to induce progestin receptor synthesis in those areas of the brain which mediate sexual behavior, the mediobasal hypothalamus (MBH) and the preoptic area (POA). In this study, we explored the temporal relationship between inducible progestin receptors in both MBH-POA and pituitary and the time course of estrogen activation of mating behavior. Both mating behavior and cytosol [3H]R5020 binding in brain and pituitary increase monotonically when Silastic capsules containing 17β-estradiol are implanted and decrease monotonically when the capsules are removed. After implantation of estradiol, increases in cytosol [3H]R5020 binding are seen at 12, 24, 36, and 48 h. Receptivity is first observed at 18 h; subsequent increases in the lordosis quotient score are seen at 24, 36, and 48 h. After 48 h, inducible progestin receptors in both MBH-POA and pituitary are maximal, and sexual receptivity is approaching maximal levels. After removal of estradiol, decreases in cytosol [3H]R5020 bind...
TL;DR: The results of these and other studies suggest that the cytoplasmic levels of cyclic AMP in the isolated oocyte are high enough to maintain meiotic arrest if a phosphodiesterase inhibitor is present, and gonadotropins seem to affect the oocyte indirectly, via the cumulus cells, possibly by interrupting communication between the two cell types.