Pairing of the stimulus to the cerebral peduncle (CP) with that to the forearm skin leads cats to flex their forearms within a 10-day training period in response to stimulus to CP, which was initially ineffective. Behavioral study and extracellular unit analysis suggested that the cellular mechanism for this conditioning lies at the corticorubral (CR) synapses. Since formation of new CR synapses occurs in parallel with the recovery from behavioral deficits after brain damage and peripheral nerve cross-innervation, we explored the possibility that the formation of new CR synapses underlies conditioning. We investigated the time course of the CR excitatory postsynaptic potentials (EPSPs) as well as the distribution of the CR synapses on the somadendritic membrane of the red nucleus neurons and compared them with those observed in control animals. In conditioned animals, the times-to-peak of the CR EPSPs were significantly shorter than those in control animals. Electron microscopic studies demonstrated that more CR synapses make contact with large, i.e. proximal, dendrites and somata of red nucleus neurons in conditioned cats than in control ones. These results support the view that the formation of new synapses on the proximal dendrites and soma underlies classical conditioning in the cat.

Animals↗

PubMedDate not supplied

Decreased hepatic nitric oxide synthesis during liver surgery.

BACKGROUND/AIMS: Liver cells can produce nitric oxide from L-arginine through the action of nitric oxide synthase, but local changes in the concentrations of nitric oxide-related metabolites during liver surgery are not well characterized. We investigated such changes during and after liver surgery. METHODOLOGY: We determined nitrite plus nitrate, L-arginine and L-citrulline concentrations in radial arterial and hepatic venous blood during and after liver surgery in 17 patients. Portal venous blood concentrations were also measured at the end of surgery in 7 patients. RESULTS: Both arterial and hepatic venous nitrite plus nitrate concentrations were significantly decreased during surgery and remained low compared to pre-operative values until post-operative day 2. Arterial and hepatic venous nitrite plus nitrate concentrations were not significantly different. L-arginine concentrations in both arterial and hepatic venous blood were significantly decreased during surgery, but returned to pre-operative levels on post-operative day 1. L-arginine concentrations in hepatic venous blood were significantly lower than in arterial blood. L-citrulline concentrations in both arterial and hepatic venous blood were significantly decreased during surgery compared to pre-operative values, and tend to be decreased until post-operative day 2. L-citrulline concentrations were significantly higher in hepatic venous blood than in arterial blood. CONCLUSIONS: Hepatic nitric oxide production was decreased peri-operatively during liver surgery. The decreases in L-arginine concentrations and in nitric oxide synthase activity may account for the decrease in nitric oxide production.

Adult↗

PubMedDate not supplied

Levels of interleukin (IL)-6, IL-8, and IL-1 receptor antagonist in the hepatic vein following liver surgery.

BACKGROUND/AIMS: The liver produces various cytokines, but local changes in the concentrations of these reaction products after liver surgery are unknown. We investigated the local changes of interleukin-6, interleukin-8 and interleukin-1 receptor antagonist after liver surgery. METHODOLOGY: We determined levels of interleukin-6, interleukin-8, and interleukin-1 receptor antagonist in the hepatic vein and radial artery after liver resection in 13 patients. These cytokine levels in the portal vein were also measured in 6 patients. RESULTS: Interleukin-6, interleukin-8, and interleukin-1 receptor antagonist levels were significantly increased during liver surgery (P < 0.05). The level of interleukin-6 was significantly lower in the hepatic vein than in the radial artery as well as in the portal vein at the end of the operation (P < 0.05, < 0.03). The level of interleukin-8 and interleukin-1 receptor antagonist was significantly higher in the hepatic vein than in the artery (P < 0.05). CONCLUSIONS: Interleukin-6 may be taken up by the liver after liver surgery, and the difference between hepatic venous and peripheral arterial interleukin-6 levels may be an indicator of liver regeneration after liver resection. Interleukin-8 and interleukin-1 receptor antagonist appear to be produced in the remaining liver.

Aged↗

PubMedDate not supplied

[Proceedings: 264. Cable properties of red nucleus neurons (author's transl)].

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Membrane Potentials↗

PubMedDate not supplied

Effect of vinconate against alterations in [3H]naloxone, [3H]MK-801 and [3H]muscimol bindings after transient cerebral ischemia in gerbils.

We examined the alterations of opioid (naloxone), N-methyl-D-aspartate and gamma-aminobutyric acidA receptors in the gerbil brain 7 days after cerebral ischemia using [3H]naloxone, [3H]MK-801 and [3H]muscimol autoradiography, respectively. We also evaluated the effect of vinconate against the alterations in these receptors. Transient cerebral ischemia was induced for 10 minutes, and vinconate (100 and 300 mg/kg) was given intraperitoneally 10 minutes before ischemia. [3H]MK-801 binding showed a more severe reduction than [3H]naloxone binding 7 days after cerebral ischemia, whereas [3H]muscimol binding was unchanged in almost all brain regions. Vinconate showed a significant prevention against the reduction in [3H]naloxone binding in all brain areas. This drug also prevented a significant reduction in [3H]MK-801 binding in most of the brain regions. Furthermore, [3H]muscimol binding in vinconate-treated gerbils exhibited a significant increase compared with that in sham-operated animals. These results show that opioid and N-methyl-D-aspartate receptors are very sensitive to transient cerebral ischemia, whereas gamma-aminobutyric acidA receptors are particularly resistant. They also suggest that vinconate has a potent protective effect against the alterations of opioid and N-methyl-D-aspartate receptors. These findings might be of interest in relation to the mechanism of ischemic neuronal damage.

Animals↗