Na+ independent binding of [3H] muscimol to a membrane fraction of the brains of normal and dwarf mice

Although their body weights were decreased by about 77% and their brain weights by about 30%, high-affinity [3H] muscimol binding to a cerebral membrane fraction was not altered in hereditary pituitary dwarf mice. Marked changes in the level of pituitary growth-associated hormones do not appear to be associated with a change in cerebral GABA-receptors.     

Effect of an LH-RH antagonist on reproductive status of immature female rats

Summary Administration of the LH-RH antagonist, D-Phe²-D-Ala⁶-LH-RH (Wy-18, 185) to immature female rats from days 25–35 of age was without significant effect on day of vaginal opening (puberal onset), weights of the ovaries, uteri and anterior pituitary, and on ovarian histology on autopsy day 39.The technical expertise of J. Tracy is gratefully acknowleged.     

Pentagastrin induction of acetylcholinesterase activity in cerebral cortex of rats

Summary A single injection of pentagastrin (500 g kg^–1) produced an immediate (within 15 min) and pronounced increment (about 50%) in the activity of acetylcholinesterase (AChE) in the cerebral but not in the cerebellar region of the brain. Pretreatment of rats with either actinomycin-D or cycloheximide did not fully abolish the pentagastrin-mediated stimulation of cerebral AChE activity.Acknowledgments. A.M. Nakhla is recipient of a postdoctoral research fellowship from Danida, Ministry of Foreign Affairs, Denmark. The project was in part supported by grants to A.P.N.M. from The Laegevidenskabelige Forskningsråd and Danida, Denmark.     

Differences in luteinizing hormone release stimulated in rat anterior pituitary cells by leukotriene C4 and by gonadotropin-releasing hormone in vitro

Summary Continuous administration of leukotriene C₄ (LTC₄, 10^–10 M) to superfused rat anterior pituitary cells increased LH release for 40 min only, whereas in a parallel experiment gonadotropin-releasing hormone (GnRH, 10^–9 M) evoked a continuous increase in hormone secretion. In contrast to GnRH, LTC₄ did not desensitize rat anterior pituitary cells. The secretory action resulting from the administration of LTC₄ (10^–10 M) was abolished for 40 min after previous stimulation. The results documented the dual action of LTC₄ on LH exocytosis.     

High sensitivity of porcine cerebral arteries to endothelin

Summary The threshold concentration of endothelin to induce contractions in porcine cerebral arteries (anterior cerebral, Willis ring and basilar artery) was lower than those for coronary and renal arteries. The median effective concentrations (ED₅₀) of endothelin in cerebral arteries were also significantly lower than those for coronary and renal arteries. There was no significant difference in the sensitivity to endothelin among cerebral arteries, or between coronary and renal arteries. The maximal percentage of contractions induced by endothelin, as compared to that induced by 10^–1 M potassium chloride, was not significantly different between the arteries.     

The lack of an effect of cholinergic agonists on anterior pituitary prolactin production in vitro

Summary The addition of dopamine to anterior pituitary incubations resulted in a marked decrease (88% for³H prolactin and 69% for RIA prolactin) in prolactin release. Incubation with the cholinergic agonists carbacol, arecoline and nicotine resulted in no significant change in prolactin secretion.Supported in part by NSF Research grant No. BMS 74-17332.The authors appreciate receiving as a gift from the National Institute of Arthritis, Metabolic and Digestive Diseases, the rat prolactin used for iodination (RP-I₂) and standards (RP-1).     

Influence de l'humidité sur les cocons du Ver à soie(Bombyx mori)

Summary Experiments were carried out to test the effects of relative humidity on prepupae and pupae of the Silkworm,Bombyx mori L., at 25⁰ C. It was found that:(1) duration of prepupal + pupal stages is the same at all relative humidities between 7 and 100%;(2) mortality seems unaffected in all these humidity conditions;(3) moths obtained in percentages between 55 and 100% R. H. have the same average wet weight; moths obtained under dryer conditions have a lower average weight (expressed in percentage of initial weights of prepupae);(4) pupae extracted from their cocoons develop as quickly and as well as pupae in their cocoons.     

High K+-induced release of somatostatin from the cortical preparation of rat brain

Summary Release of endogenous somatostatin (SRIF) from the rat cerebral cortical slices incubated in Krebs-bicarbonate buffer was increased from the basal rate of 3.4±0.6% of the total SRIF content in 15 min at [K⁺]_o=5.6 mM, to 13.1±1.6% upon raising the [K⁺]_o to 56.6 mM. The high-K⁺ evoked SRIF release was absent when Ca⁺⁺ in the medium was replaced by Mn⁺⁺. The isolated synaptosomes from rat cerebral cortex contain 13.2±3.1 ng SRIF/mg protein compared to 0.33±0.01 ng/mg protein in the cortical tissue as a whole, suggesting that nerve terminals are the main source of the peptide released upon membrane depolarization.The study was supported by a grant from the Medical Research Council of Canada. Results of this work have been published in part as abstracts: Can. Physiol.9, 45 (1978), and Fedn Proc.37, 665 (1978).The authors are greatly indebted to Dr M. Gotz and the Ayerst Research Laboratories for the most generous supply of the synthetic somatostatin.     

Influence of ethanol on thyroxine accumulation in the hypothalamus,pituitary gland and cerebrospinal fluid in the newborn rabbit

Summary The effect of ethanol on thyroxine (T₄) accumulation in the hypothalamus (H), pituitary gland (P) and cerebrospinal fluid (CSF) has been investigated in 1–15-day-old rabbits. It has been found that H or CSF serum ratios decreased with age by about 2 in the course of 13 postnatal days. Stable T₄ resulted in an increase of¹²⁵I-T₄ in H, P and CSF. Ethanol per se caused an increase in transfer and accumulation of radiothyroxine or made the changes after loading animals with carrier T₄ more pronounced.     

Inhibition of prostaglandin-induced cyclic AMP accumulation in the rat anterior pituitary by alrestatin

Summary Alrestatin at 25–1×10^–4 M inhibited the accumulation of cyclic AMP induced by prostaglandin E₂, but not theophylline, in the rat anterior pituitary in vitro. Somatostatin, at lower concentrations, inhibited both; maximal inhibition of the prostaglandin effect was greater with alrestatin. As cyclic AMP is considered to be a mediator in induced-hormonal release, it appears from the present findings that alrestatin may be of potential use in altering hormonal release.The author acknowledges the technical assistance of Miss C. Pilapil.     

Re-evaluation of protein kinase CK2 pleiotropy: new insights provided by a phosphoproteomics analysis of CK2 knockout cells

CK2 denotes a ubiquitous and pleiotropic protein kinase whose holoenzyme is composed of two catalytic (α and/or α′) and two regulatory β subunits. The CK2 consensus sequence, S/T-x-x-D/E/pS/pT is present in numerous phosphosites, but it is not clear how many of these are really generated by CK2. To gain information about this issue, advantage has been taken of C2C12 cells entirely deprived of both CK2 catalytic subunits by the CRISPR/Cas9 methodology. A comparative SILAC phosphoproteomics analysis reveals that, although about 30% of the quantified phosphosites do conform to the CK2 consensus, only one-third of these are substantially reduced in the CK2α/α′^(?/?) cells, consistent with their generation by CK2. A parallel study with C2C12 cells deprived of the regulatory β subunit discloses a role of this subunit in determining CK2 targeting. We also find that phosphosites notoriously generated by CK2 are not fully abrogated in CK2α/α′^(?/?) cells, while some phosphosites unrelated to CK2 are significantly altered. Collectively taken our data allow to conclude that the phosphoproteome generated by CK2 is not as ample and rigidly pre-determined as it was believed before. They also show that the lack of CK2 promotes phosphoproteomics perturbations attributable to kinases other than CK2.     

Effect of estradiol on aminoacid incorporation into proteins of different hypothalamic areas in prepuberal rats

Summary Estradiol in vitro produces a significant increase in the incorporation of³H-leucine into proteins of the anterior hypothalamic area in prepuberal female rats, 15 and 20 days old, but not in younger animals. The ovarian hormone induced no changes in the protein synthetic activity of middle and posterior hypothalamus and cerebral cortex in prepuberal female rats of different ages. Estradiol did not modify the protein synthesis of the hypothalamus and cerebral cortex in prepuberal male rats.Supported by a grant from the Consejo Nacional de Investigaciones Cientifícas y Técnicas de la República Argentina.     

Effect of experimental diabetes on estradiol binding by the anterior pituitary and hypothalamus in ovariectomized rats

Summary In diabetic rats,³H-estradiol binding by the cytosol and nuclei of the anterior pituitary was lower than normal. Changes in affinity and receptor numbers were demonstrated by Scatchard analysis. Protein synthesis in diabetic pituitaries, however, was in the normal range.     

Effect of sodium octanoate on leucine incorporation into protein of rat liver slices and of Yoshida ascites hepatoma cells

Summary 7.38×10^–4 M octanoate does not significantly modify leucine incorporation into protein of rat liver slices, while in hepatoma cells a 19% inhibition has been noted.3.69×10^–3 M octanoate reduces leucine incorporation to about the same extent (71–76%) in both liver slices and hepatoma cells.     

Chemistry of some potent animal toxins

Conclusion I have discussed in this article only the most active toxins, with the result that many interesting substances have been omitted, e.g. the toxins from bee and wasp venoms (apamin, melittin, etc.), of many amphibians (bufotoxins, etc.), ciguatoxins, and many more. Poisons are found in every phylum except birds. Shrews exemplify venomous mammals. One gets a good illustration of the number of poisonous animals by studying the monumental and impressive work byHalstead ¹⁰⁶ which consequently excludes terrestrial animals. An interesting fact in this connection is that there are about 20,000 species of spiders, most of which are poisonous.A toxin ranking list has to be included in an article of this kind. The list is, of course, far from complete. Data on molecular weights, mouse lethal doses, etc. are lacking for many potent toxins, such as the dysentery toxin, a neurotoxin with a toxicity comparable to that of the botulinus toxins¹⁰⁷, the toxins from the jelly fishChironex fleckeri ¹⁰⁶.A comparison on molar basis gives a better notion of the toxicities. Curare has about 1/30 of the toxicity of the curarimimetic snake venom neurotoxins, clearly indicating that curare has a much lower affinity for the acetylcholine receptor.Toxic organisms have developed during millions of years more and more refined toxins, and this evolution has probably brought into existence toxins against every physiological function. Neurochemistry is to a great extent unexplored. Progress in this field will in the nearest future depend on specific toxins from various natural sources. Toxins from spiders, scorpions, snakes, frogs, and fishes are therefore not mere curiosities but valuable tools for research on the molecular mechanisms of neural function and synaptic transmission.     

Localization of a new neuroleptic in the pituitary gland of the rat

summary The¹⁴C-labelled, substituted benzamide neuroleptic Tiapride has been found to accumulate transiently in the pituitary gland of the rat following a single dose, and a prolonged retention of the drug was observed in the pars intermedia.     

Respective roles of circulating T4 and T3 in control of TSH secretion in severely iodide-deficient rats

Summary After a 6-month iodide deficiency, Wistar male rats were submitted to a normal iodine diet (20 and 50 g of¹²⁷I daily). Plasma T₃, T₄ and TSH were determined by RIA from 0 to 140 days of iodide refeeding. A highly significant correlation was found between plasma TSH and T₄ concentrations, but not between plasma TSH and T₃ levels. These data suggest that an increase in plasma T₃ alone, up to the normal value, is not able to inhibit TSH secretion. It is only when a certain plasma T₄ concentration is also reached, resulting in further T₃ formation through deiodination, that TSH secretion is inhibited.Dedicated to the memory of Prof. C. Simon.This work was supported by grants from the CNRS (Equipe de Recherche Associée no 234) and from the INSERM (A.T.P. 49.77.8).Acknowledgments. The authors wish to thank Mrs M. Chartier for valuable technical assistance. They are indebted to the rat pituitary distribution programme of NIAMDD, NIH, Bethesda, for their gift of rat TSH reagents.     

The ischemic and postischemic effect on the uptake of neutral amino acids in isolated cerebral capillaries

Summary The uptake of some neutral amino acids was investigated in cerebral microvessels isolated from brains of gerbils subjected to bilateral cerebral ischemia with and without various periods of recovery. A transiently increased capillary uptake of³H-isoleucine,¹⁴C-cycloleucine and³H-phenylalanine was found in both conditions.     

Cellular and subcellular localization of3H-diethylstilbestrol in the pituitary,oviduct and uterus of the female rat

Summary Female rats were injected with³H-diethylstilbestrol. The pituitaries, oviducts, and uteri were removed and processed for autoradiography. The nuclear uptake and retention in these tissues appeared similar to that seen after the injection of³H-estradiol except in the pars nervosa of the pituitary gland.This study was supported by US PHS Career Development Award No. NS00164 and PHS Grant No. NS21933.