[Indications for antidepressive agents in relation to diseases of the cardiovascular system]. / Indikace antidepresív ve vztahu k onemocnením kardiovaskulárního systému.

Antidepressants, in particular tricyclic ones (TCA), and inhibitors of monoaminooxidase (IMAO) exert a number of undesirable cardiovascular effects. TCA and IMAO frequently cause postural hypotension (PH). IMAO administration is associated with the risk of hypertensive crisis. TCA raises the heart rate and can cause abnormalities in the conduction of the cardiac excitation. TCA are contraindicated after myocardial infarction and are the cause of death after overdosage. When PH is undesirable, in hypertension and cardiac insufficiency the following safe antidepressants are recommended: nortriptyline, mianserine, trazodone and viloxazine. In abnormalities of conduction of the cardiac excitation and after myocardial infarction only mianserine, trazodione and viloxazine are recommended. With regard to cardiovascular toxicity, antidepressants from the series of selective inhibitors of serotonin reabsorption are very promising: fluvoxamine, fluoxetine, citalopram, paroxetine and sertraline. The same applies also to the reversible IMAO type A moclobemide.

Tonic immobility and factors influencing its duration in rats.

The author developed a method for inducing tonic immobility (paroxysmal inhibition) in rats and mice. By means of a plexiglass plate and plexiglass box the rat is immobilised, rotated at 180 degrees and subjected to constant pressure corresponding to the weight of the plexiglass plate. This way it is possible to prolong substantially tonic immobility in rats without using foregoing time consuming and interfering, so called sensitizing procedures. The duration of TI can be influenced by pharmacologic and nonpharmacological interventions. A longer duration of TI appeared to be typical for rats tending to react in other situations with anxiety, motor inhibition and submission.

Responses to the change in the environment in pairs of male rats genetically selected for activity level.

Laboratory Wistar strain rats were genetically selected for high (+A) and low (-A) activity level. In thirteen pairs of adult males of the 23rd filial generation reactions to changes in the external environment were studied. The animals were housed in breeding cages four each. Two parallel studies were conducted: in pairs simultaneously placed into a novel environment (NOV), empty cages of the same dimensions as the home cage (HC), in the second, behaviour of the second pair that remained in the HC, after removal of two cage-mates, was tested. Once a minute, for a period of one hour, the type of activity was recorded and noted whether it was an element effected in contact with the partner or without any contact. The animals +A and -A differed in the frequency of various types of activity and immobility, in the ratio between behavioural manifestations shown in or without contact as well as in the response to the type of modified environment. To changes in the situation, whether removed cage-mates from the HC or placed into NOV +A animals reacted with a high wave of environment exploration which gradually habituated. -A rats equally responded with exploration but on a lower level. In +rats we recorded more frequently exploration without contact with the partner in HC and NOV in comparison with -A, more frequent grooming, less immobility in contact and with no contact. Between +A partners there was a greater number of contacts in NOV than in HC whereas in the -A group the incidence of contact did not differ between HC and NOV. ANOVA revealed the influence of factors of genetics and environment and interaction in several behavioural categories. The simple and in time economical method demonstrated the possibility of use for the detection of differences between +A and -A lines even at relatively small changes in the external stimulatory situation.

Correlation between the duration of perphenazine catalepsy and pressure maintained tonic immobility under the influence of beta-sympathotropic agents.

In rats the effect of i.p. applied beta-adrenomimetic isoprenaline (ISO) 0.4 mg/kg, sulbutamol (SAL) 2mg/kg, beta-adrenoblocker propranolol (PRO) 2 mg/kg and metipranolol (MET) 4 mg/kg on the duration of perphenazine-induced catalepsy (CAT) and pressure-maintained tonic immobility (TI) was studied. It appeared that a mild constant pressure on the rat body permitted to measure the length of duration of TI in adult rats. The time course of changes in the duration of CAT and TI was repeatedly measured in one-hour intervals with different results. While ISO had no effect on the duration of CAT, SAL prolonged it. Both beta-symathomimetic compounds prolonged the duration of TI. PRO and MET shortened the duration of CAT. PRO did not influence, MET failed in the first phase but in the second phase it significantly prolonged TI duration. In spite of a certain affinity of both phenomena the two, that is, CAT and TI were not parallely influenced by the betasympathotropic agents used.

New apparatus for training the avoidance reaction.

A new apparatus for active avoidance training in rats consists of a short, wide runway which can be tilted from a horizontal to vertical position. One half of the electrifiable grid floor is covered by a nonconducting sheet. For brightness (black-white) discrimination training a white walled goal box can be inserted into the runway and shifted from left to right during training. Avoidance training of 24 rats (female Wistar SPF) required 14.1 +/- 2.6 (mean +/- SEM) to-criterion trials (9/10) and was completed in less than 4 min. Brightness discrimination training required 21.3 +/- 2.1 to-criterion trials and the time of training did not exceed 12 min. The retention of the acquired responses was very good in both cases. The main advantage of the apparatus is very rapid acquisition of the one-way and discriminated avoidance without the necessity of manual manipulation of the animal.