[S-adenosyl-L-homocysteine: 1. Influence on sleep]

S-Adenosylhomocysteine, 0.1-20 mg/kg, influences the sleep patterns of rat, cat and rabbit by increasing the slow-wave and fast-wave sleep for 6 h. The SAH effects are increased by p-chlorophenylalanine and iproniazid and unchanged by reserpine. SAH effects are correlated with modification of norepinephrine and serotonin metabolism.

Effect of cholecystokinin and pentagastrin on motility and gastric secretion in the cat

The effects of cholecystokinin (CCK; 0.25-16 IDU kg-1h-1), synthetic octapeptide of CCK (OP-CCK; 0.5-2 microgram kg-1h-1) and pentagastrin (0.5-8 microgram kg-1 h-1) on pepsin secretion and antral motility were compared in conscious cats with reference to acid secretion. The results confirmed that the 3 peptides are full agonists for acid secretion and showed that they also displayed the same action on antral motor activity in increasing the frequency and decreasing the force of the contractions. Their effects on pepsin secretion were of different efficacy, decreasing from pentagastrin to CCK and to OP-CCK which showed a very weak action.

In vitro and in vivo myocardial effects of a cyclic AMP phosphodiesterase inhibitor structurally related to natural cardenolides

The myocardial effects of the lactonic deoxybenzoin glucoside, AP 10, an ATPases and cyclic AMP phosphodiesterases inhibitor, were investigated in vitro and in vivo. AP 10 showed marked positive inotropic effects on spontaneously beating frog and mammal isolated hearts. This drug induced a substantial increase in cyclic AMP atrial level comparable to that observed with papaverine in the rat. Its inotropic effects on stimulated rat left atria were moderate and suppressed by reserpine pretreatment, in contrast with papaverine inotropic effects which were not significantly modified. As papaverine (10(-5) M), AP 10 (10(-4) M) shifted to the left the atrial dose-response curve for isoproterenol. The positive inotropic effects of AP 10 were more pronounced at low calcium concentrations. Furthermore, AP 10 prolonged the time course of tension decline in stimulated rat left atria exposed to Ca++ free medium. AP 10 (1 mg/kg) did not induce any in vivo hemodynamic disturbance in both anaesthetized and conscious dogs and significantly improved ventricular automaticity in anaesthetized dogs (0.5 mg/kg). This drug was also compared to quinidine in two in vivo experimental arrhythmias. AP 10 was more effective than quinidine in preventing ouabain-induced arrhythmias in conscious rabbits and electrically-induced atrial fibrillation in conscious dogs. Despite its ATPases inhibiting properties and some structural similarities with cardiac glycosides, AP 10 did not show a typical "digitalis-like" pharmacological profile. It exhibited some of the myocardial features which characterize phosphodiesterase inhibitors as caffeine, papaverine or Ro 7-2956. An interesting particularity of AP 10 action was its capacity to prevent experimental arrhythmias.

Activation by S-adenosylhomocysteine of norepinephrine and serotonin in vitro uptake in synaptosomal preparations from rat brain

S-Adenosylhomocysteine (10(-7)-10(-5) M) activated norepinephrine (NE) and serotonin (5HT) in vitro uptake in synaptosomal preparations from rat brain, but did not affect dopamine (DA) uptake. When administered to rats (7 mg/kg i.p.), it has the same effect on in vitro NE and 5HT uptake. It did not affect NE and 5HT release.

Action of S-adenosyl-L-homocysteine on the metabolism of dopamine, norepinephrine and serotonin in rat brain

S-Adenosylhomocysteine (SAH) (0.1 to 30 mg/kg/i.p.) increased 3H-norepinephrine synthesis from 3H-tyrosine in the rat brain stem and mid brain, but did not alter its tissular level. It decreased both the serotonin level and the formation of 3H-serotonin from 3H-tryptophan and increased the formation of 3H-5hydroxyindolacetic acid. Its effects began 1 hr after administration and was still present 6 hr later. It did not alter dopamine metabolism. A correlation between the hynotic effect of SAH and the modification of the metabolism of cerebral monoamines was pointed out.

[Effects of S-adenosylmethionine and S-adenosylhomocysteine on in vivo synthesis of noradrenaline and serotonin in different parts of the rat brain]

S-adenosylmethionine (0,1 mg/kg/ip) decreases in vivo, norepinephrine (NE) synthesis and does not affect 5-hydroxytryptamine (5 HT) synthesis in the Rat brain. S-adenosylhomocysteine (7 mg/kg/ip) increases NE synthesis and decreases 5 HT synthesis. Neither nucleoside affects dopamine synthesis.

A basic relationship between gastric and duodenal motilities in chickens

Chickens were chronically fitted with a duodenal cannula and pairs of electrodes implanted in the wall of the muscular stomach, duodenum and ileum. Smooth muscle electrical activity was recorded in both fed and fasted conditions under a 12--12 h dark-light schedule. Two major patterns of activity were identified. The first consisted of spike bursts that propagated rapidly either aborally from the stomach or orally from the ileum. Aborad-propagated spike bursts were most frequent during the daytime; this circadian variation was abolished by vagotomy, which also increased the frequency of orad-propagated spike bursts. The second pattern was characterized by periods of repetitive spike bursts lasting 3--10 min and spreading aborally at a slower rate. In the fasted chicken, the daily frequency was increased and the period of repetitive spike bursts resembled the prolonged bursts of spike potentials recorded in the feline small intestine. The results suggest that the propulsion of digesta might depend on the ratio of spike bursts moving aborally from the stomach to those moving orally from the ileum. Both factors were influenced by the level of stomach activity.

Study of the motility of the avian oviduct with chronically implanted electrodes

Electrical activity was recorded in conscious hens from chronically implanted electrodes in the smooth muscle layers of the oviduct. Transport of the egg through the magnum resulted from an inhibition of the electrical activity in the oviduct cranial to the egg and an increased spiking activity caudally. During an ovulatory cycle the progression of the egg was related to four different patterns of the uterine motility: within a sequence, the ovulatory cycles varied according to the duration of Phases 3 and 4.

Optic neuritis in the Landry-Guillain-Barré-Strohl syndrome

A patient with typical Landry-Guillain-Barré-Strohl syndrome (LG-BS) developed bilateral optic neuritis. Laboratory studies showed hypersensitivity to both central and peripheral nervous tissue myelin. The occurrence of optic neuritis is presumably due to autohypersensitivity to central nervous tissue myelin. The initial lesions of the LG-BS syndrome in the peripheral nerves might have liberated sequestered antigens that cross-reacted with central nervous system myelin.

Influence of male and female Nippostrongylus brasiliensis on each other's distribution in the intestine of the rat

Nippostrongylus brasiliensisof either sex, 216 h old, were injected directly in the intestinal lumen of 10-week-old laparotomized male rats in the duodenum or near the ileocaecal valve and their position ascertained 24 h later. Males migrated anteriad farther when females were placed in the duodenum than when they were alone or when 32P tagged males were in the duodenum. Females migrated anteriad similarly when they were alone or when males were in the duodenum or when 32 P tagged females were injected in the duodenum. The findings are consistent with the idea that females attract males anteriad at a distance.