Fine-structural heterogeneity and morphologic changes in rat pituitary prolactin cells after estrogen and testosterone treatment

Summary This study was conducted to determine the functional and/or developmental relationships among three heterogeneous types of prolactin cells (I, II and III) in rats. Rats were injected subcutaneously daily with estradiol or testosterone propionate on days 10–20 after birth. Estradiol increased the proportion of cell types II and III, increased serum PRL levels 12-fold in males and 15-fold in females, and increased pituitary levels of prolactin 12-fold in males and 5-fold in females. Testosterone mainly increased the proportion of the Type-II cells, decreased serum levels of prolactin in males only, and did not change pituitary levels of prolactin. In a second experiment, treatment of rats with nafoxidine for five days after E₂ treatment (days 10–20 after birth) increased the proportion of Type-I cells and decreased the proportion of Type-III cells and decreased serum and pituitary levels of prolactin by 50% in females and by 15 and 45% in males. In a third experiment utilizing adult male rats, estradiol and testosterone were found to modulate the relative ratios of the different types of PRL cells as they did in immature animals. The data taken as a whole suggest the possibility of an estrogen-stimulated conversion of one cell type to another, which may be a reflection of prolactin secretory activity.This work was supported by a Scientific Research Grant from the Ministry of Education, Science and Culture of Japan (No. 57770038)     

Photochemical reaction of 9-cis-retro-γ-rhodopsin at low temperatures

9-cis-Retro-γ;rhodopsin (λ_max = 420 nm) was prepared from 9-cis-retro-γ-retinal and cattle opsin. After cooling to liquid nitrogen temperature (77 K), the pigment was irradiated with light at 380 nm. The spectrum shifted to the longer wavelengths, owing to formation of a batho product. This fact indicates that the conjugated double bond system from C-5 to C-8 of the chromophoric retinal in rhodopsin was not necessary for formation of bathorhodopsin. Reirradiation of the batho product with light at wavelengths longer than 520 nm yielded a mixture composed of presumably 9- or 11-cis forms of retro-γ-rhodopsin. These three isomers are interconvertible by light at liquid nitrogen temperature. Thus the retro-γ-rhodopsin system is similar in photochemical reaction at 77 K to cattle rhodopsin system. Each system has its own batho product. Based on these results, it was infered that the formation of bathorhodopsin is due to photoisomerization of the chromophoric retinal of rhodopsin and is not due to translocation of a proton on the ring or on the side chain from C-6 to C-8 of the chromophoric retinal to the Schiff-base nitrogen.     

Fine structural criteria for identifying rat corticotrophs

Summary The fine structural characteristics of normal rat corticotrophs stained with anti-porcine ACTH^1–39 serum were studied. At the ultrastructure level immunoreactive corticotrophs appear to comprise four distinct cell types: (1) large stellate cells (Siperstein cells) containing granules (170–250 nm in diameter) arranged in a peripheral row and usually embracing an acidophil; (2) elongate spindle-shaped cells (Moriarty cells) in which the secretory granules (170–250 nm in diameter) are distributed in a row or in small clusters in the peripheral cytoplasm; (3) oval or polygonal cells filled only with small secretory granules (130–170 nm in diameter), resembling the acidophil of small granules type (Yoshimura et al. 1974); and (4) polygonal or stellate cells filled with secretory granules of varying diameters (180–300 nm in diameter) and occasionally embracing an acidophil. The first type is the most common, but the others are infrequent. It is concluded that the criteria of Siperstein and Miller (1970) do not necessarily include all categories of rat corticotrophs.     

Radioimmunoassay for β-endorphin: Presence of immunoreactive “big-big” β-endorphin (“big” β-lipotropin) in human and rat pituitaries

A sensitive and specific radioimmunoassay for β-endorphin has been developed with an antiserum obtained in a rabbit immunized with β-endorphin contained in crude porcineACTH preparations. The minimal detectable quantity was 5 pg. The antiserum used reacted slightly with ovine β-lipotropin (5.5 %), but showed negligible cross-reactivity with other fragments of β-lipotropin, α-MSH and ACTH. Using this radioimmunoassay we have observed the presence of “big-big” β-endorphin (“big” β-lipotropin) with apparent molecular weights of 37,000 and 31,000 in human and rat pituitaries respectively, in addition to β-lipotropin and β-endorphin, by Sephadex gel-chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis.     

Effect of furosemide on urinary excretion of prostaglandin E in normal volunteers and pateints with essential hypertension

Urinary excretion of prostaglandin E was measured radioimmunologically in 19 healthy persons ( 15 men and 4 women ) and in 16 patients ( 10 men and 6 women ) with essential hypertension before and after the administration of furosemide. The excretion rates were increased from 26.3±3.0 to 64.5±11.3 ng/hr in the former and from 11.9±2.7 to 26.9±85 ng/hr in the latter. There was a significant difference between them, healthy subjects showing a greater increase than patients with essential hypertension.There was an obvious sexual difference in urinary excretion of prostaglandin. In men, greater increase in the excretion rates was found than in the women. Greater increases were also obtained in healthy men than in hypertensive men and in healthy women than in hypertensive women. The present results suggest that furosemide enhances urinary excretion of prostaglandin E by mechanisms which entails either an increase in prostaglandin synthesis or a decrease in renal metabolism.     

Automated determination of orotic acid, uracil and pseudouridine in urine by high-performance liquid chromatography with column switching

A column-switching high-performance liquid chromatographic method, requiring no sample preparation apart from filtration, is described for quantification of urinary orotic acid, uracil and pseudouridine. The analyses were carried out using a reversed-phase octadecylsilane-bonded column for sample clean-up and a cation-exchange column for separation; 5–20 ]sml samples of urine were directly analysed, and more than 100 samples could be analysed consecutively. Each sample required only 30 min. Detection limits of these compounds were 5 pmol. Creatinine-related urinary uracil excretion was lowest in the newborn period (17.3 ± 14.4 μmol/g of creatinine). A patient with partial ornithine transcarbamylase deficiency and his mother usually excreted a high level of uracil during the period of normal orotic acid excretion and normal serum ammonia level.     

Synthesis of 2,2,2-trichloroethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranoside,and its reaction with glycosyl halides.

2,2,2-trichloroethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranoside (9) was synthesized in 6 steps from the readily available 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranose in 25% overall yield by employing the stannyl method for the regioselective activation of hydroxyl groups. Dibenzyl ether 9 was then glycosylated with appropriate glycosyl donors to afford lactosamine and chitobiose derivatives in good yield.     

Synthesis of 3,6-di-O-acetyl-2-deoxy-2-phthalimido-4-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-β-d-glucopyranosyl chloride

A lactosaminyl donor, 3,6-di-O-acetyl-2-deoxy-2-phthalimido-4-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-β-d- glucopyranosyl chloride, was synthesized in 10 steps, starting from 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranose. Benzyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranoside was prepared by regioselective benzylation at the primary hydroxyl group by the stannyl method, and was used as a key intermediate.

     

Disappearance of calcium-induced phase separation in phosphatidylserine-phosphatidylcholine membranes caused by protonation and by electric current

Disappearance of Ca²⁺-induced phase separation in phosphatidylserine-phosphatidylcholine membranes has been studied under several conditions by monitoring electron spin resonance spectrum of spin-labeled phosphatidylcholine. The membranes were prepared in Millipore filters. Electron micrographs of the preparations showed formation of multilayered structures lined on the pore surface. The phase separation was disappeared when the membrane was soaked in non-buffered salt solution (100 ml KCl, pH 5.5). It was markedly contrasting that when the bathing salt solution was buffered no disappearance was observed. Disappearance of the phase separation was also observed when the Ca²⁺-treated membrane was transferred to acidic salt solutions ($\text{?}\text{pH 2.5}$) or to low ionic strength media ($\text{? 10}\text{mM}$) buffered at pH 5.5, and then to the buffered salt solution (100 mM KCl, pH 5.5). These are due to replacement of Ca²⁺ by proton, proton-induced separation, followed by disappearance of the phase separation inthe buffered salt solution. Biological significance of the competition between Ca²⁺ and proton for the phase separation or domain formation in the membranes was emphasized.