Effect of galanin on substance P- and vasoactive intestinal polypeptide-induced nociceptive trigemino-hypoglossal reflex in rats.

Substance P (SP), vasoactive intestinal polypeptide (VIP) and galanin (GAL), present in primary sensory neurons, are involved in transmission of nociceptive signaling from the peripheral to central nervous system. In this study we investigated the effect of GAL on SP-induced or VIP-induced evoked tongue jerks (ETJ) in response to noxious tooth pulp stimulation during perfusion of the cerebral ventricles with SP or VIP solutions. The experiments were carried out on rats under chloralose anesthesia. It was shown that both, SP and VIP, perfused through the cerebral ventricles enhanced the ETJ amplitude as compared with control, but the effect produced by SP was stronger. The intracerebroventricular perfusion of GAL 5 minutes before SP caused a dose-dependent inhibition of SP-induced ETJ, whereas GAL perfused through the cerebral ventricles 5 minutes before VIP did not reduce the excitatory effect of VIP on ETJ. These results indicate that the antinociceptive effect of GAL perfused through the cerebral ventricles, tested on the trigemino-hypoglossal reflex in rats, is specifically mediated by the SP-ergic system.     

Effect of a substance P antagonist on capsaicin-induced nociceptive reflex in the isolated spinal cord-tail preparation of the rat

An isolated spinal cord-tail preparation of the newborn rat was developed and used for studying the effects of various drugs. The cord and the tail were separately perfused with oxygenated artificial cerebrospinal fluid. Application of capsaicin in a small amount to the tail induced a depolarizing response of the lumbar ventral root (L3-L5) lasting for about 30 sec. The stimulating action of capsaicin was potentiated by previous perfusion of the tail with a medium containing prostaglandin E1 or E2. The capsaicin-induced nociceptive reflex was depressed by application to the spinal cord of morphine, Met-enkephalin, dynorphin (1-13), somatostatin, adenosine, GABA and a substance P (SP) antagonist [D-Arg1, D-Pro2, D-Trp7,9, Leu11]SP, and potentiated by bicuculline. The present preparation will be useful for the future studies on pain and analgesic drugs.     

Naloxone effects on a nociceptive response of hypophysectomized and adrenalectomized mice

Naloxone (1 and 3 mg/kg) or saline was administered to adrenalectomized, sham-adrenalectomized, hypophysectomized, and sham-hypophysectomized mice prior to placing them on a 55° C hot plate. Naloxone reduced the jump latency of the adrenalectomized, sham-adrenalectomized, and sham-hypophysectomized mice, but did not reduce the jump latency of hypophysectomized mice. Hypophysectomy and adrenalectomy $\text{per se}$ did not significantly affect the jump latency. These results indicate that the pituitary is necessary for naloxone to reduce the escape latency of mice on the hot plate. The possibility of a hyperalgesic factor is suggested.     

The effect of substance P1-7 amide on nociceptive threshold in diabetic mice

We previously demonstrated that intrathecal treatment with substance P metabolite substance P_1-7 induced anti-hyperalgesia in diabetic mice. In the present study, we have used a synthetic analog of this peptide, the substance P_1-7 amide, showing higher binding affinitiy than the native heptapeptide, for studies of the tail-flick response in diabetic and non-diabetic mice. Intrathecal injection of substance P_1-7 amide produced prolongation of the tail-flick latency in both diabetic and non-diabetic mice, an effect that was more pronounced in diabetic mice than non-diabetic mice. Moreover, the observed antinociceptive potency of the substance P_1-7 amide was higher in both diabetic and non-diabetic mice in comparison with the native substance P_1-7. The antinociceptive effect of substance P_1-7 amide was reversed by naloxone but not by the selective opioid receptor antagonist β-funaltrexamine, naltrindole or nor-binaltorphimine, selective for the μ-, δ- or κ-opioid receptor, respectively. In addition, the antinociceptive effect induced by substance P_1-7 amide was partly reversed by the σ₁ receptor agonist (+)-pentazocine, suggesting a possible involvement of the σ₁ receptor for the action of this peptide. These results suggest that the actions of substance P_1-7 amide mimic the effects of the native substance P fragment but with higher potency and that the mechanisms for its action may involve the σ₁ receptor system.     

Intradermal hypertonic saline-induced behavior as a nociceptive test in mice

We report a nociceptive test involving peripheral irritation which produces behavior similar to that elicited by intrathecally injected substance P. Intradermal hypertonic saline injected to the lower abdominal area produced quantifiable behavior in mice. The behavior consisted of licking, biting and scratching directed to the location of i.d. injection, and was dose-dependent with respect to the concentration and volume of saline. Intrathecally administered (D-Pro2, D-Trp7,9)-SP, a substance P antagonist, dose-dependently blocked the behaviors induced by intrathecally administered substance P as well as those induced by intradermally injected hypertonic saline, indicating a possibly common final pathway at the spinal cord level for the manifestation of both behaviors. Hypertonic saline-induced behavior was blocked completely by morphine and a partial opiate agonist (pentazocine) in a dose-dependent manner, but was not blocked by another partial opiate agonist (nalorphine). The behavior was not blocked by non-steroidal anti-inflammatory agents. This nociceptive test, in conjunction with the substance P-induced behavior test, may allow discrimination between agents acting pre- or post-synaptically in the spinal cord. Baclofen, a GABAB agonist thought to act presynaptically, changed substance P-induced behavior and hypertonic saline-induced behavior in opposite directions.     

Attenuation of capsaicin-induced acute and visceral nociceptive pain by alpha- and beta-amyrin, a triterpene mixture isolated from Protium heptaphyllum resin in mice

The triterpene mixture, alpha- and beta-amyrin, isolated from Protium heptaphyllum resin was evaluated on capsaicin-evoked nociception in mice. Orally administered alpha- and beta-amyrin (3 to 100 mg/kg) significantly suppressed the nociceptive behaviors--evoked by either subplantar (1.6 microg) or intracolonic (149 microg) application of capsaicin. The antinociception produced by alpha- and beta-amyrin against subplantar capsaicin-induced paw-licking behavior was neither potentiated nor attenuated by ruthenium red (1.5 mg/kg, s.c.), a non-specific antagonist of vanilloid receptor (TRPV1), but was greatly abolished in animals pretreated with naloxone (2 mg/kg, s.c.), suggesting an opioid mechanism. However, participation of alpha2-adrenoceptor involvement was unlikely since yohimbine (2 mg/kg, i.p.) pretreatment failed to block the antinociceptive effect of alpha- and beta-amyrin in the experimental model of visceral nociception evoked by intracolonic capsaicin. The triterpene mixture (3 to 30 mg/kg, p.o.) neither altered significantly the pentobarbital sleeping time, nor impaired the ambulation or motor coordination in open-field and rota-rod tests, respectively, indicating the absence of sedative or motor abnormality that could account for its antinociception. Nevertheless, alpha- and beta-amyrin could significantly block the capsaicin (10 mg/kg, s.c.)-induced hyperthermic response but not the initial hypothermia. These results suggest that the triterpene mixture, alpha- and beta-amyrin has an analgesia inducing effect, possibly involving vanilloid receptor (TRPV1) and an opioid mechanism.     

Differential inhibitory effects of lovastatin on protein isoprenylation and sterol synthesis

It has been reported that when 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors are utilized for treatment of hypercholesterolemia, as much as 50% inhibition of whole body cholesterol biosynthesis is observed. As general inhibitors of isoprenoid biosynthesis, these compounds can also inhibit the synthesis of the substituents of isoprenylated proteins. For two mammalian proteins (p21ras and lamin A), it has been demonstrated that such inhibition of biosynthesis of the isoprenoid substituent blocks proteolytic maturation of these proteins. It has been argued that advantage may be taken of this phenomenon to block the synthesis of p21ras in malignancies. It is also possible that treatment of hypercholesterolemia with lovastatin might produce problematic inhibition of protein processing dependent upon isoprenylation. In this report, we compare the concentration dependence of inhibition of isoprenylation dependent protein processing and sterol biosynthesis. Effects of partial inhibition of isoprenylated protein processing on whole cells can be sensitively assessed by visualization of lamina structure through indirect immunofluorescence. Our results indicate that the degree of inhibition of p21ras and prelamin A maturation by lovastatin is identical. Thus, 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors are unlikely to be useful as anti-malignancy drugs. However, the conditions of lovastatin treatment which produce 50% inhibition of sterol biosynthesis analogous to pharmacological conditions, produce no observable effects on isoprenylated protein maturation.     

Differential inhibitory effects of Evans blue on various DNA polymerases

Evans Blue, an anionic dye which has been found to inhibit the replication of human immunodeficiency virus, proved also inhibitory to the DNA polymerases alpha and beta. The mode of inhibition was competitive with respect to the template X primer, and noncompetitive with respect to the deoxynucleoside triphosphate substrates. The inhibitory effect of Evans Blue on DNA polymerases is discussed in relation to that of suramin.     

Differential effects of pentobarbital and ethanol in mice

The duration of the loss of righting reflex (RR) after ethanol, 4 g/kg, intraperitoneally (i.p.), was significantly longer in “long-sleep” (LS) than in “short-sleep” (SS) mice. This effect was shown to be correlated with differences in brain sensitivities to ethanol. In contrast, pentobarbital sodium (PB), 50 mg/kg, i.p., produced a significantly longer loss of RR in SS than in LS mice. The PB concentrations in the brain were the same in both mouse strains at the time of RR recovery suggesting equal sensitivities of the central nervous systems to PB. The rates of disappearance of PB from the blood were the same in both strains, but the apparent volume of distribution of PB in the LS strain was greater than in SS mice.In addition, C57BL/6J mice were found to be more sensitive than DBA/2J mice to PB, 50 mg/kg. In contrast, C57BL mice are known to be less sensitive than the DBA strain to ethanol. The PB concentration in the brain of DBA mice at the recovery of the RR was significantly greater than in C57BL mice. The apparent volumes of distribution of PB were not different in the two strains, but the rate of disappearance of PB from the blood of C57BL mice was significantly greater than for the DBA strain. In conclusion, factors which govern the brain sensitivities of selected mouse strains to ethanol and pentobarbital may not be equivalent.     

Differential effects of DBMIB and DNP-INT on the kinetic phases of P-700 reduction

In the presence of ferredoxin and NADP, DBMIB abolishes the fast-relaxing portion of P-700 together with the reduction of NADP. The slow-relaxing portion is inhibited at much higher concentrations. Qualitatively similar results have been observed with DNP-INT. However, its action appears to be a light-dependent process. The slow, cyclic turnover of P-700 in the presence of DCMU, ferredoxin and NADPH is inhibited by DBMIB but only slightly by DNP-INT. The data suggest that the inhibitors act at different sites of the electron-transport system.     

Differential inhibitory effects of sophoricoside analogs on bioactivity of several cytokines

Effects of sophoricoside and its analogs on proinflammatory cytokines have been investigated. Sophoricoside, genistein and orobol exhibited inhibitory effects on IL-5, IL-3, GM-CSF and IL-6 bioactivities. Genistin showed inhibitory effects on IL-5 and IL-3 bioactivities, but did not inhibit GM-CSF and IL-6 bioactivities. None of the sophoricoside analogs showed inhibitory effects on both IL-1beta and TNF-alpha bioactivities. Among the compounds, sophoricoside exhibited the highest inhibitory effects on IL-5, IL-3 and IL-6 bioactivities with IC50 values of 1.9 microM, 6.9 microM and 6.0 microM, respectively and orobol did show on GM-CSF bioactivity with an IC50 value of 18.0 microM. The result would provide an additional mechanism by which the compounds exert immunosuppressive and anti-inflammatory effects.     

Diverse effects of intrathecal pituitary adenylate cyclase-activating polypeptide on nociceptive transmission in mice spinal cord

Pituitary adenylate cyclase-activating polypeptide (PACAP) immunoreactive neural elements have been detected in the mouse spinal cord. The discrepancy of PACAP actions in the role of sensory transmission has been proposed to have potentiation and inhibition on nociceptive responses after intrathecal application of PACAP. The aim of the present study was to assess nociceptive transmission of PACAP in the mouse spinal cord by comparison with that of substance P (SP). The intrathecal injection of PACAP induced licking or scratching behavior similar to that of SP. These PACAP-induced aversive behaviors showed different manner from SP-induced responses in point of time course. SP-induced aversive responses quickly increased and suddenly disappeared almost within 1 min. Meanwhile, following a long latency after the injection, PACAP-induced aversive responses gradually appeared, and then persisted more than 60 min. In the early phase, PACAP produced an increase of tail flick latency. Pretreatment with 6-hydroxydopamine (6-OHDA) which destroys noradrenaline neuron of descending pain inhibitory systems in the spinal cord markedly abridged the latency and augmented the duration of PACAP-induced aversive responses. In this way, PACAP exhibits diverse effects on nociception, such as an analgesic role in early phase of the injection and subsequently lasting algesia. These results suggest that PACAP as a neurotransmitter or neuromodulator might have crucial role in nociceptive transmission system.     

Anxiety stress and nociceptive responses in mice

Nociception in laboratory animals appears to be influenced by physical or emotional stressors. Nevertheless, the reported data are not univocal. Discrepancies seem to be caused by some kind of stress model and/or by the timing of stressor application. The aim of the present work is to study the influence of chronic application of a well-controlled and defined anxiety stress paradigm (rotational stress) on the behavioral formalin pain responses in mice maintained in a low-stress environment. The results indicate that emotional chronic stress increases specific pain responses in the late inflammatory phase and, correspondingly, decreases self-grooming. Locomotor activity appears influenced by pain presence only. The hormonal and neural mechanisms that could be involved in the observed nonspecific and specific nociceptive responses to stress are discussed.     

Differential inhibitory effects of actinomycin D among strains of poliovirus

Schaffer, Frederick L. (University of California, Berkeley), and Marjorie Gordon. Differential inhibitory effects of actinomycin D among strains of poliovirus. J. Bacteriol. 91:2309-2316. 1966.-Actinomycin D exerted a differential effect on the ability of strains of poliovirus to replicate in HeLa cells. LSc-2ab was studied as an example of a strain markedly inhibited by actinomycin; MEF(1) served as a control strain with minimal inhibition. The effect was noted at an actinomycin concentration of 0.1 mug/ml, but 2.5 mug/ml was used for most studies. Variability in the effect was attributed, in part, to physiological factors. Actinomycin was effective when present during the first 2 hr of LSc infection, but had little effect if present at later times. It did not block adsorption or initiation of ecilpse. It did block synthesis of ribonucleic acid in LSc-infected cells. Several possible modes of action are discussed, the most attractive being that actinomycin blocks synthesis of some cell component, the concentration of which is more critical for replication of some poliovirus strains than others.     

Feeding-deterrent substance in cattle feces: its effects on ingestive behavior in goats

A feeding-deterrent substance was isolated from cattle feces and its effects on ingestive behavior were examined in goats. The substance was added to alfalfa hay and presented to the goats in the following experiments. In a two-choice test, between control fodder and the fodder treated with the substance, animals avoided eating treated fodder. This food-deterrent effect was strengthened in a dose-dependent manner. The results of ingestive behavior analysis suggested that this substance affected the goats through olfaction. However, in a single-presentation test, where the goats had no choice, no effect on ingestive behavior was noticed. It is therefore suggested that the preference induced by the substance is relative rather than absolute in the ingestive behavior of goats.     

Differential effects of strychnine on crustacean slow, fast, and inhibitory neuromuscular systems

The effect of strychnine was studied on the slow, fast, and inhibitory systems in the abdominal extensor muscles of the crayfish. Strychnine nitrate (0.1 mg/ml and up) caused rapid block of the fast responses of the deep abdominal extensor muscles. The nerve and muscle remained directly excitable, and the blocked preparation contracted with added glutamate. It is concluded that strychnine acts mainly presynaptically or to neutralize the transmitter substance. No marked effect was observed on the purely slow superficial extensor muscles or on inhibitory systems. Essentially the same results were obtained in other slow and fast systems of Pachygrapsus and Panulirus. The possibility of a common transmitter substance for the slow and fast neuromuscular systems is discussed.     

Differential effects of pressure or volume overload on myocardial MMP levels and inhibitory control

Left ventricular (LV) pressure (PO) or volume (VO) overload is accompanied by myocardial remodeling, but mechanisms that contribute to this progressive remodeling process remain unclear. The matrix metalloproteinases (MMPs) contribute to tissue remodeling in a number of disease states. This study tested the hypothesis that increased MMP expression and activity occur after the induction of an LV overload, which is accompanied by a loss of endogenous MMP inhibitory control. LV MMP zymographic activity and species abundance were measured in dogs under the following conditions: acute PO induced by ascending aortic balloon inflation (6 h, n = 9), prolonged PO by aortic banding (10 days, n = 5), acute VO through mitral regurgitation secondary to chordal rupture (6 h, n = 6), prolonged VO due to mitral regurgitation (14 days, n = 7), and sham controls (n = 11). MMP zymographic activity in the 92-kDa region, indicative of MMP-9 activity, increased over threefold in acute PO and VO and fell to control levels in prolonged PO and VO. The MMP-9 activity-to-abundance ratio increased by over fourfold with acute VO and twofold in acute PO, suggesting a loss of inhibitory control. Endogenous MMP inhibitor content was unchanged with either PO or VO. Interstitial collagenase (MMP-1) content decreased by 50% with acute VO but not with acute PO. Stromelysin (MMP-3) levels increased by 40% with acute VO and increased by 80% with prolonged PO. Although changes in LV myocardial MMP activity and inhibitory control occurred in both acute and prolonged PO and VO states, these changes were not identical. These results suggest that the type of overload stimulus may selectively influence myocardial MMP activity and expression, which in turn would affect the overall LV myocardial remodeling process in LV overload.