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Biomedical subjects

F Hoffmeister

Publications and source records attributed to F Hoffmeister.

15 recordsLinked to original sources
PubMed1979

Endogenous brain angiotensin II disrupts passive avoidance behavior in rats.

The presence of angiotensinogen, the precursor of angiotensin II (ANG II), in brain tissue and in cerebrospinal fluid (CSF) allows stimulation of endogenous brain ANG II by renin. Passive avoidance tests were performed in female Wistar rats. The animals received an electrical shock after entering a black box on the first experimental day. Avoidance was tested every 24 h for 5 consecutive days. Renin in doses of 0.01 and 0.1 units was injected once into the lateral brain ventricles 2 min before the first test. CSF ANG II increased from 40 to 4547 and 5152 fmol per ml (means), respectively. A dose-dependent disruption of avoidance learning was observed, the frequency to enter the black box increasing from 11% (control) to 29% and 46%, and the latency decreasing from 165 (control) to 143 and 116 sec, respectively. These effects were statistically significant (P less than 0.001) for more than 24 h and returned to control levels after 48 to 120 h. Administration of the converting-enzyme inhibitor SQ 14225 i.v.t. prior to renin injections abolished the renin effects. Injections of renin given 22 h after learning were without effect.

Angiotensin II↗
PubMed1979

Reinforcing properties of nicocodine in the rhesus monkey.

The present study demonstrates that nicocodine is self-administered by the rhesus monkey in cross self-administration experiments. The minimum reinforcing dose is 10 times higher than that of codeine and 100 times higher than that of heroin. At reinforcing doses the rate of self-administered infusions of nicocodine is comparable with those of codeine. Further experiments are necessary to rank order nicocodine as to its positive reinforcing properties among the opiate-like compounds. On the other hand the present experiments demonstrate that nicocodine is an opium-like reinforcing compound.

Animals↗
PubMed1979

[A new method for enteral self administration of psychotropic drugs in the rhesus monkey (author's transl)].

This surgical method for the parenteral self administration of psychoactive substances in the Rhesus monkey is a modified gastrostomy. Success is warranted with a catheter-model which can be fixed at the inner wall of the abdomen. The catheter is placed subcutaneously until it leaves between the shoulders. Additionally all monkeys received leather corsets. This method has proved to be very safe in long-time self administration of drugs in the Rhesus monkey.

Animals↗
PubMed1979

The antithrombotic activity of BAY g 6575.

The activity of 1-[2-(beta-naphthyloxy)ethyl]-3-methyl-2-pyrazolin-5-one (= BAY g 6575) was evaluated in models of experimental thrombosis caused by traumatically induced damage of vessel segments. After prophylactic administration of BAY g 6575 (0.3 mg/kg p.o.) to rats the thrombus formation was significantly reduced in the carotid artery as well as in the jugular vein. The thrombus formation in the femoral arteries of rabbits is inhibited at a minimal effective dose of 1 mg/kg p.o. The incidence of occlusive thrombi is not influenced. BAY g 6575 is 10 times more potent than acetylsalicylic acid (ASA). In the arterial system the thrombus formation is frequently completely abolished.

Animals↗
PubMed1977

Self-administration of codeine plus acetylsalicylic acid in rhesus monkeys with unlimited access to the drugs.

The reinforcing effects of codeine (5.0 mcg/kg/infusion), acetylsalicylic acid (ASA) (2500 mcg/kg/infusion) and those of combinations of codeine (50 mcg/kg/infusion) plus (2500 or 10,000 mcg/kg/infusion) were studied in four groups of drug naive rhesus monkeys. Responding was engendered and maintained by infusions of 50 mcg/kg of codeine; maximal number of daily infusions being 500 to 1000. Infusions of 2500 mcg/kg of ASA plus 50 mcg/kg of codeine per infusion initiated responding from the 9th to the 10th day of the drug period on. The number of self-administered infusions did not exceed 200 daily. Monkeys self administered codeine without signs of intoxication. All three monkeys self-administering the combination of 50 mcg/kg of codeine plus 2500 mcg/kg of ASA died during the experiment. They exhibited signs of severe intoxication. A combination of 50 mcg/kg of codeine and 10,000 mcg/kg of ASA was not self-administered until the 12th day of the drug period. Two out of three monkeys initiated responding for the combination during the drug period. The number of self-administered infusions did not exceed 50 per day. A third monkey did not initiate self-administration during the 14 day drug period. Both monkeys which engendered self-administration died on the 14th day of the experiment as a result of general intoxication. These experiments suggest that even toxic doses of ASA will not prevent monkeys from self-administration when offered together with a positive reinforcing drug such as codeine under a schedule of continuous self-administration.

Animals↗
PubMed1977

Pharmacology of Bay g 2821, a long-acting, high-ceiling diuretic.

Bay g 2821 is a diuretic, from a new class of chemical substances, with both the efficacy of diuretics with a high-ceiling activity, such as furosemide, bumetanide and ethacrynic acid, and the prolonged duration of action of thiazides. Pharmacological investigations showed that Bay g 2821 was more potent than furosemide in dogs but less potent in rats. Bay g 2821 did not differ from furosemide in excretion of electrolytes. Further studies showed that Bay g 2821 had an antihypertensive effect in dogs, spontaneously hpertensive rats, and in rats with artificially-induced renal hypertension. Other pharmacological studies did not reveal any other significant effects.

Animals↗
PubMed1977

Reinforcing properties of perphenazine, haloperidol and amitryptiline in rhesus monkeys.

Possible negative reinforcing effects of perphenazine, haloperidol and amitryptiline were studied in rhesus monkeys previously trained to avoid electric shock by responding. Responding extinguished a light associated with an intravenous drug infusion scheduled to occur 30 seconds after the light was switched on. A response occurring when the light was on switched the light off for a period of 1 minute (time-out period). a response during the infusion terminated the infusion. Under these conditions, the monkeys tolerated a large number of saline infusions. Saline was replaced by different doses of perphenazine, haloperidol and amitryptiline, each for 12 successive daily 2-hour sessions. Infusions of perphenazine (0.50-1.6 microng/kg) and to a lesser extent infusions of haloperidol (2.5 microng/kg) generated and maintained responding. Most of the infusions of amitryptiline in the dose range of 1.0 to 10.0 microng/kg were tolerated. Haloperidol and perphenazine in doses higher than 10.0 micmitryptiline (500-3000 microng/kg i.v.) had no influence on shock avoidance behavior. Positive reinforcing effects of these compounds were studied in a group of monkeys trained to respond under a 10 response fixed ratio of intravenous infusions of codeine. None of the three compounds maintained responding previously engendered by codeine.

Amitriptyline↗
PubMed1975

Negative reinforcing properties of some psychotropic drugs in drug-naive rhesus monkeys.

Rhesus monkeys, previously trained to avoid electric shock, pressed a lever to extinguish a light associated with an intravenous drug infusion scheduled to occur 30 seconds after the onset of the light. Each response when the light was on terminated the light for a 1-minute time-out period (avoidance); a response during the infusion terminated the infusion (escape). Under these conditions the monkeys tolerated a high number of saline infusions. Saline was replaced by different doses of chlorpromazine, lysergic acid diethylamide (LSD) and pentobarbital each for six successive daily 2-hour sessions. Infusions of chlorpromazine (5.0-20 mug/kg/infusion) or LSD (1.0-2.5 mug/kg/infusion) generated and maintained avoidance/escape behavior, whereas most of the infusions of pentobarbital (10-100 mu/kg/infusion) were tolerated. In rhesus monkeys with no previous drug experience, chlorpromazine and LSD, but not pentobartital, have negative reinforcing properties.

Animals↗
PubMed1975

Further studies on self-administration of antipyretic analgesics and combination of antipyretic analgesics with codeine in rhesus monkeys.

The possible reinforcing effect of acetylsalicylic acid (ASA) was studied in a group of rhesus monkeys that had no history of self-administration of drugs. Rates of lever pressing were compared under conditions in which each lever-pressing response resulted in an infusion of saline, an infusion of saline plus delivery of a food pellet or an infusion of ASA (0.4, 1.0, 2.5 OR 5.0 MG/KG /infusion). Responding was engendered and maintained by the delivery of food pellets but not by infusions of saline alone nor by ASA; however, responding was subsequently engendered and maintained in these monkeys by codeine (0.05 mg/kg/infusion). In another group of monkeys that had been trained to respond under a 10-response fixed-ratio schedule of i.v. infusions of codeine, the possible reinforcing effects of aminophenazone, phenylbutazone and of combinations of each of these drugs with codeine were studied. Aminophenazone and phenylbutazone (0.4-5.0 mg/kg/infusion) did not maintain responding previously engendered by codeine. Mixtures of aminophenazone and phenylbutazone with codeine decreased the number of codeine self-administrations. Thus, codeine intake was reduced when aminophenazone and phenylbutazone were added to codeine in the solution to be self-administered. These experiments suggest that antipyretic analgesics are not effective in reinforcing behavior in the rhesus monkey.

Aminopyrine↗
PubMed1975

Antinociceptive action and plasma levels of acetylsalicylic acid in the dog.

1. The analgesic potency of acetylsalicylic acid (ASA) is four times greater when administered intravenously than when administered orally. 2. The onset of the ASA analgesia after oral administration is significantly slower (30-60 min) than after intravenous (5-15 min) application. However, the duration of ASA-analgesia after oral administration is significantly longer (5 h) than after i.v. (2-4 h) application. 3. The onset and duration of ASA-analgesia in dogs after oral and i.v. administration cannot be correlated with plasma levels of ASA. During the period of analgesia, ASA can be detected only in extremely low concentrations, since it appears to be very rapidly hydrolysed to SA. 4. The development of an accurate and reproducible method for the separate determination of ASA and SA in plasma facilitated the direct correlation of plasma levels of these substances with ASA-induced analgesia.

Administration, Oral↗