Diazepam action onγ-aminobutyric acid-activated chloride currents in internally perfused frog sensory neurons

The Cl- current (ICl) in gamma-aminobutyric acid (GABA)-sensitive frog sensory neuron was separated from other Na+, Ca2+, and K+ currents using a suction pipette technique which allows internal perfusion under a single-electrode voltage clamp. Diazepam (DZP) itself evoked no response but facilitated the dose- and time-dependently GABA-induced ICl without changing the GABA equilibrium potential (EGABA) at concentrations ranging widely, from 3 X 10(-9) to 10(-4) M. In the presence of DZP, the GABA dose-response curve shifted to the left without changing the maximum current, indicating that DZP modifies the interaction between GABA and its receptor rather than affecting directly the channel activation step. The enhancement of the GABA-induced ICl by DZP depended neither on the membrane voltage nor on the inward or outward direction of the ICl. DZP also potentiated the ICl elicited by GABA agonists such as beta-alanine, taurine, homotaurine, 5-aminovaleric acid, l-GABOB, d-GABOB, glycine, and muscimol. The GABA response enhanced by pentobarbital (PB) was further enhanced by adding DZP, indicating that DZP and PB do not act in the same way. Ro5-3663, a diazepam analogue, enhanced the GABA-induced ICl only in a narrow range of the concentrations but inhibited the current at concentrations higher than 2 X 10(-6) M.     

Characteristic pattern of monoaminergic nerve fibers in the pineal organ of the monkey,Macaca fuscata

Summary Monoaminergic nerve fibers were studied in the pineal organ of the monkey, Macaca fuscata, by use of fluorescence and immunohistochemical procedures. Abundant formations of noradrenergic nerve fibers were observed in the pineal organ. They entered the parenchyma in the form of several coarse bundles via the capsule in the distal portion of the organ and spread throughout the organ after branching into smaller units. The density of the autonomic innervation decreased gradually toward the proximal portion of the organ. In the distal portion, numerous nerve fibers formed perivascular plexuses around the blood vessels and some fibers ran as bundles unrelated to the blood vessels in the stroma. Fine varicose fibers and bundles derived from these plexuses penetrated among the pinealocytes. However, only a few intraparenchymal fluorescent fibers were detected in the proximal third of the gland. With the use of serotonin antiserum serotonin-immunoreactive nerve fibers were clearly restricted to the ventroproximal part of the pineal organ. Although the somata of the pinealocytes showed intense immunoreactivity, their processes were not stained. In one exceptional case, clusters of pinealocytes displaying very intense immunoreactivity were found in an area extending from the distal margin of the ventral portion of the pineal stalk to the proximal portion of the pineal organ proper; these cells were bipolar or multipolar and endowed with well-stained processes.     

Glucagon-related peptides in the rat hypothalamus

Summary Immunohistochemically, nerve fibers and terminals reacting with anti-N-terminal-specific but not with anti-C-terminal-specific glucagon antiserum were observed in the following rat hypothalamic regions: paraventricular nucleus, supraoptic nucleus, anterior hypothalamus, arcuate nucleus, ventromedial hypothalamic nucleus and median eminence. Few fibers and terminals were demonstrated in the lateral hypothalamic area and dorsomedial hypothalamic nucleus. Radioimmunoassay data indicated that the concentration of gut glucagon-like immunoreactivity was higher in the ventromedial nucleus than in the lateral hypothalamic area. In food-deprived conditions, this concentration increased in both these parts. This was also verified in immunostained preparations in which a marked enhancement of gut glucagon-like immunoreactivity-containing fibers and terminals was observed in many hypothalamic regions. Several immunoreactive cell bodies were found in the ventromedial and arcuate nuclei of starved rats. Both biochemical and morphological data suggest that glucagon-related peptides may act as neurotransmitters or neuromodulators in the hypothalamus and may be involved in the central regulatory mechanism related to feeding behavior and energy metabolism.     

Diurnal K+ and Anion Transport in Phaseolus Pulvinus

Diurnal movement of Phaseolus leaf is caused by deformationof the laminar pulvinus located at the joint of the leaf bladeand the petiole. The plants were cultured in solutions withvarious ion compositions, and changes of K⁺, Na⁺, Ca²⁺, Mg²⁺,Cl^–, NO₃– and P₁ concentrations both in the upperand lower parts of the laminar pulvinus were measured. Culturein 10 mM KCl solution caused an increase in K⁺ and Cl^–concentrations both in the upper and lower parts without anysignificant change in the concentration of NO₃^–; culturein 10 mM KNO₃ solution caused an increase in K⁺ and NO₃^–concentration without any significant change in the concentrationof Cl^–; and culture in 10 mM KH₂PO₄ solution caused anincrease in K⁺ and P₁ concentrations without any significantchange in the concentrations of NO₃- and Cl^–. K⁺ moved from the upper to lower parts or from the lower toupper parts diurnally in all plants cultured in any solutionmentioned above. The main inorganic anion that accompanied thisK⁺ movement was Cl^– in KCl solution, and NO₃^– inKNO₃ solution. When the seedlings were cultured in distilledwater or in KH₂PO₄ solution, neither Cl^– NO₃^– norP₁ accompanied this K⁺ movement. In these cases, mainly H⁺ and/ororganic anions are supposed to move in exchange for and/or incombination with K⁺ movement. (Received November 8, 1982; Accepted June 13, 1983)     

An inducible lactone hydrolase yielding 2,5-diphenyl-3-hydroxy-4-oxo-2-hexendioic acid from pulvinic acid

The metabolism of vulpinic acid by an unclassified soil micro-organism was studied. A new compound, 2,5-diphenyl-3-hydroxy-4-oxo-2-hexendioic acid (DHOHA) was isolated from the reaction mixture of a cell-free preparation and pulvinic acid. The existence of a hydrolase which catalyses the conversion of vulpinic acid to pulvinic acid was detected in cell-free preparation, and an inducible lactone hydrolase capable of converting pulvinic acid to DHOHA was purified 130-fold and characterized. This enzyme had a MW of ca 34 000, a K_m for pulvinic acid at pH optimum (pH 7.0) less than 10 ^{? 6} M, pI = 5.0, and was inhibited by p-chloromercuriphenylsulfonate and diethylpyrocarbonate. The enzyme was highly specific for pulvinic acid. The initial degradative steps proposed for this organism are vulpinic acid → pulvinic acid → DHOHA.     

Isoform variants of troponin in skeletal and cardiac muscle cells cultured with and without nerves

Immunofluorescence microscopy shows that cultured skeletal and cardiac muscle cells of chicken embryos exhibit the same stainabilities with antibodies against skeletal and cardiac troponin components as do those in embryos. Muscle cells of each type cultured with motor or sympathetic nerves or in medium containing the nerve extract exhibit the same reactivities as do those in adult animals. Cardiac muscle cells incubated in the nerve-conditioned medium also change the form of troponin components to the adult type. It appears that the differentiation of individual muscle fibers to specific types is induced by nerves, and especially by the neurohumoral effect.     

Control of the Orientation of Cilia by Adenosinetriphosphate,Calcium, and Zinc in Glycerol-Extracted Paramecium caudatum

The predominant orientation of cilia in glycerol-extracted Paramecium is toward the posterior of the specimen in a KCl solution. The cilia became reoriented toward the anterior shortly after transfer of the extracted cell to a mixture of ATP, calcium, and zinc. The degree of response was graded as a function of the concentration of each of the three essential factors. Minimum concentrations for the maximum response were 0.2 mM in ATP, 0.8 mM in calcium, and 0.0002 mM in zinc. The observations support the hypothesis that cation-induced ciliary reversal in live specimens is initiated by calcium ions which become displaced from an inferred cellular cation exchanger system.     

Origin of the Thymidine Kinase Induced by Polyoma Virus in Productively Infected Cells

Cells of the 3T3 mouse line efficiently supported the multiplication of polyoma virus, and the infectious process was accompanied by a marked increase in thymidine kinase (TK) activity. Two lines of 5-bromodeoxyuridine-resistant 3T3 cells have been isolated. As expected, these cells incorporated practically no exogenous thymidine into their deoxyribonucleic acid (DNA) and contained negligible TK activity. Like the parental 3T3 cells, TK(-) lines were susceptible to productive infection by polyoma virus, but infection did not lead to an increase in TK activity. Since kinase activity did appear after infection with another virus (vaccinia) known to contain the gene(s) for that enzyme, it is concluded that TK is not one of the gene products of polyoma virus. As induction of cellular DNA synthesis by polyoma virus occurs normally when the TK(-) cells are infected in the stationary phase, TK cannot play a role in the determination of this phenomenon.     

Decrease of Atrial Natriuretic Peptide Content in Rat Superior Cervical Sympathetic Ganglion After Denervation and Axotomy

We found atrial natriuretic peptide (ANP), known as a humoral factor in regulating body fluid volume and blood pressure, in considerable quantities in rat superior cervical sympathetic ganglion (SCG) by radioimmunoassay after separation with reverse-phase HPLC. Although the ANP content of the immature rat 1 week after birth was low, it doubled at 2 weeks and then increased gradually, until it reached the adult level. Denervation caused a rapid decrease in the ANP content to half of the intact SCG level after 3 h, which then fell to 10% of the control value on day 2 after operation. The time course of ANP content reduction after denervation was similar but rather faster than that of activity of the acetylcholine-synthesizing enzyme, choline acetyltransferase, an observation suggesting that ANP may partly contribute to cholinergic synaptic transmission. On the other hand, axotomy produced a rather slower decrease in the ANP content than did denervation. Enucleation and sialoadenectomy also caused a considerable reduction of the ANP content. Thus, part of the ANP found in the ganglion is apparently transported from sympathetically innervated extraganglionic organs via retrograde axoplasmic flow.     

Effects of vanillin and o-vanillin on induction of DNA-repair networks: modulation of mutagenesis in Escherichia coli

Vanillin and its isomer o-vanillin have an effect on the adaptive and SOS responses, as well as mutagenesis, induced in Escherichia coli by N-methyl-N-nitrosourea (MNU) and UV irradiation, potentiating in some cases and suppressing in others. o-Vanillin markedly inhibited the MNU-induced adaptive response, while both vanillins potentiated the UV-induced SOS response. These phenomena appear to be responsible for the comutagenic or antimutagenic role of these chemicals in MNU and UV mutagenesis.