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C Köhler

Publications and source records attributed to C Köhler.

At least 199 records · Page 11Linked to original sources
PubMed1979

Regional displacement by sulpiride of [3H]spiperone binding in vivo. Biochemical and behavioural evidence for a preferential action of limbic and nigral dopamine receptors.

The regional displacement by sulpiride of [3H]spiperone binding in vivo was studied in the rat. A low dose of sulpiride (20 mg/kg) displaced [3H]spiperone binding in certain limbic regions (olfactory tubercle, septum) and the substantia nigra but not in the nucleus accumbens or striatum. At this does sulpiride preferentially blocked apomorphine induced apomorphine Higher doses of sulpiride (150 and 250 mg/kg), which blocked apomorphine induced stereotypes and induced catalepsy were found to displace [3H]spiperone binding in all regions studied including the striatum and the nucleus accumbens. Haloperidol (0.1 and 1.0 mg/kg) displaced [3H]spiperone to approximately the same extent in all regions studied.

Animals↗
PubMed1979

Forebrain projections of the ventral tegmentum as studied by axonal transport of [3H]dopamine in the rat.

Twenty-four hours after [3H]dopamine ([3H]DA) injections into different parts of the ventral tegmentum the radioactivity recovered in the forebrain showed a highly regional distribution which corresponded to well-known DA projections. Selective degeneration of DA-neurons with 6-hydroxydopamine (6-OHDA) markedly reduced the axoplasmic transport after [3H]DA injections. The ventral tegmental area (VTA) was found to project primarily to the nucleus accumbens, olfactory tubercle and amygdala. The DA-innervation of the entorhinal cortex and the amygdala derive from cells widely distributed in the VTA and SN.

Animals↗
PubMed1979

Intrahippocampal injections of ibotenic acid provide histological evidence for a neurotoxic mechanism different from kainic acid.

Stereotaxic injections of ibotenic acid (IBO) and kainic acid (KA) into either the dorsal hippocampus or the lateral cerebroventricle were performed in order to determine the relative potencies of the drugs and the vulnerability of different hippocampal cell types to their neurotoxic action, IBO was found to be approximately five times less potent than KA in causing degeneration of hippocampal neuronal cell bodies. Unlike KA (0.5 and 1.0 microgram), IBO (5.0 micrograms) caused few signs of intrahippocampal bleeding or necrosis of non-neuronal elements. Pyramidal cells of the CA3 and CA4 regions were the most sensitive and dentate granule cells the least sensitive to KA. In contrast, IBO cused degeneration of granule cells and CA3/CA4 pyramids to an equal extent.

Animals↗
PubMed1978

Open field activity and avoidance behavior following serotonin depletion: a comparison of the effects of parachlorophenylalanine and electrolytic midbrain raphe lesions.

Three experiments were performed in order to compare the behavioral effects of electrolytic destruction of the dorsal and median mesencephalic raphe nuclei (MR lesion) and parachlorophenylalanine (pCPA; 300 mg/kg, IP) administration. Forebrain 5-hydroxytryptamine (5-HT) was measured in all animals following completion of behavioral testing. In the first experiment open field behavior (one 50 min session) and two-way (shuttle) conditioned avoidance acquisition (50 massed trials) were examined 68-72 hr after vehicle or pCPA administration in rats which had received control operations or MR lesions two weeks earlier. Only the MR lesion and the MR lesion + pCPA groups evidenced increased open field activity and facilitated two-way avoidance learning. Although the reduction in forebrain 5-HT of the pCPA group (85%) was greater than in the MR lesion group (55%), the pCPA treated animals did not differ from the control group. In the second experiment animals were tested in the open field 24, 48 or 72 hr after pCPA treatment to determine its effects on activity level as a function of the time after injections. No differences between the vehicle and pCPA groups, however, were found. In the third experiment, the effects of pCPA (72 hr postinjection) on the acquisition of an unsignalled one-way avoidance response was examined. MR lesion rats tested in the same apparatus and with the same procedure repeatedly have been shown to be impaired in this task. The pCPA and vehicle animals, however, did not differ. Reduction in 5-HT following electrolytic MR lesions and pCPA administration, thus, produce different behavioral effects. MR lesions, but not pCPA treatment, result in (1) increased activity in a novel environment, (2) facilitated two-way conditioned avoidance learning, and (3) impaired acquisition of an unsignalled one-way avoidance response. These data support earlier studies suggesting that the behavioral effects of electrolytic MR lesions are not due primarily to their disruption of ascending 5-HT pathways. The role of 5-HT in avoidance conditioning and the regulation of activity level, furthermore, remains to be elucidated.

Animals↗
PubMed1976

Activity, avoidance learning and regional 5-hydroxytryptamine following intra-brain stem 5,7-dihydroxytryptamine and electrolytic midbrain raphe lesions in the rat.

Rats underwent one of the following treatments: (1) electrocoagulation of both the dorsal and median midbrain raphe nuclei; (2) 5,7-dihydroxytryptamine creatinine sulfate (5,7-DHT) injection (10 mug, as the salt, in 5 mul vehicle) into the vicinity of each midbrain raphe nucleus; (3) intra-brain stem vehicle (5 mul of 0.2% ascorbic acid in isotonic saline) injections; or, (4) a control operation. Open field activity and one-way avoidance conditioning were examined on postoperative days 16-23. Regional central 5-hydroxytryptamine (5-HT) and catecholamine (CA) concentrations were determined 25-27 days postoperatively. Regional 5-HT levels were greatly reduced following 5,7-DHT administration and electrolytic raphe lesions. The 5,7-DHT rats also showed a reduction in spinal 5-HT content. Central CA concentrations were not affected. Variation in the pattern of regional 5-HT changes after 5,7-DHT treatment was observed but appeared to be related to the adequacy of the dorsal raphe (B7) injection. Only the electrolytic raphe lesion animals, however, showed increased locomotor activity and retarded acquisition and forced-extinction of the one-way avoidance response. In contrast, no significant differences were observed in the open field and avoidance behavior of the 5,7-DHT, vehicle, and control groups. The hyperactivity and impaired one-way avoidance performance observed after electrolytic midbrain raphe lesions are not related simply to reductions in regional forebrain 5-HT and may well be due to damage of non-serotonergic neural systems. Clearly, the behavioral effects of central 5-HT depletion depend on the method employed. The role of 5-HT in regulating activity level and mediating avoidance behavior, furthermore, remains to be determined.

Animals↗
PubMed1975

[Influence of temperature on the bioelectric conductivity of peripheral motor nerve].

14 persons were examined electro-neurographically before and after cooling with an ice bag. The following results were found. A slight decrease of the motor conductivity is verified. This decrease in function is shown most markedly in the slowly-conducting motor neurons. At the cooling borderlines reactions with increased function are discernible. For the clarification of the relevance of changes of the nerve conductivity, further investigations with methodic variants are necessary.

Adult↗