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J Braszko

Publications and source records attributed to J Braszko.

15 recordsLinked to original sources
PubMed1999

[The influence of angiotensin converting enzyme inhibitors on the central nervous system].

Angiotensin converting enzyme inhibitors (ACEI) constitute 23% of all antihypertensive drugs world-wide (WHL Newsletter, October 1997). Although lipophilic ACEIs like captopril, trandolapril or perindopril may decrease blood pressure partly via central nervous system (CNS) they also are capable of evoking a range of psychotropic effects. Basing on our recent experiments and the literature data we discussed possible effects of ACEIs on mood and cognition.

Affect↗
PubMed1996

The contribution of AT1 and AT2 angiotensin receptors to its cognitive effects.

In this study I attempted to assess, in rats, the role of AT1 and AT2 angiotensin receptor subtypes in the phenomenon of improved learning and memory after an intracerebroventricular (icv) injection of angiotensin II (Ang II) and Ang II (3-7). Selective AT1 (losartan, 1 mg) or AT2 (CGP 42112 A, 2 micrograms) receptor antagonist was dissolved in 2 microliters of saline and given to the left cerebral ventricle 5 min before 1 nmol Ang II or Ang II (3-7) injected in the same volume of saline to the right ventricle. Consequently, there were 9 experimental groups which underwent 3 memory oriented and 3 auxiliary tests. Ang II and Ang II (3-7) significantly improved retention of the passive avoidance and recognition memory. These effects were abolished by losartan or CGP 42112 A. Better, after Ang II and Ang II (3-7), acquisition of conditioned avoidance responses was unchanged by losartan and abolished by CGP 42112 A. None of the treatments significantly changed rats motor behaviour in open field. Losartan as well as CGP 42112 A abolished significant enhancement of apomorphine (1 mg/kg, i.p.) stereotypy caused by Ang II and Ang II (3-7). The results suggest considerable involvement of AT1 and AT2 angiotensin receptors in the cognitive enhancement produced by angiotensins.

Angiotensin I↗
PubMed1996

Behavioural activity of angiotensin II (3-7)4Phe--analogue of natural fragment 3-7 of angiotensin II.

A study was made of the influence of pentapeptide 3-7 angiotensin II [AII(3-7)], its analogue 3-7(4)Phe [AII(3-7)4Phe] and angiotensin II (AII) on the behaviour of adult male rats. The motility, stereotypy, spatial performance, learning of conditioned and passive avoidance responses allowing to avoid aversive stimulation were estimated. Examined peptides at the dose 1 nmol injected intracerebroventricularly 15 min before the experiment did not produce specific changes in psychomotor activity in the "open field" test and in retention of the spatial task in the Morris water maze. The rate of acquisition of conditioned avoidance responses was stimulated by AII(3-7)4Phe, AII(3-7) and AII administration. In the passive avoidance situation AII improved retention of the responses whereas analogue AII(3-7)4Phe and fragment 3-7 caused similar though less pronounced effect. All the peptides applied immediately before the experiment intensified stereotypy, a behaviour evoked by of apomorphine-1 mg/kg and amphetamine-7.5 mg/kg intraperitonealy injection. These results show similar psychotropic activity of analogue AII(3-7)4Phe, comparable with the activity of natural fragment 3-7 of angiotensin II.

Analysis of Variance↗
PubMed1992

Angiotensin II--derived peptides devoid of phenylalanine in position 8 have full psychotropic activity of the parent hormone.

In this work we compared in rats the influence of heptapeptide 1-7-angiotensin II, hexapeptide 2-7-angiotensin II, pentapeptide 3-7-angiotensin II and angiotensin II on motility, stereotypy, learning of conditioned avoidance responses and recall of passive avoidance behaviour allowing to avoid aversive stimulation. The 4 peptides administered 15 min before the experiment, tended to increase the number of crossings, rearings and bar approaches in open field, significantly accelerated acquisition of conditioned avoidance responses and improved recall of the passive avoidance. All the peptides applied immediately before the experiment intensified stereotypy evoked by apomorphine in the dose 1 mg/kg and amphetamine in the dose 6.5 mg/kg given intraperitoneally. These results show full psychotropic activity of the examined fragments of angiotensin II, comparable with the activity of the parent octapeptide. Our previous hypothesis that the Val-Tyr-Ile-His-Pro fragment of angiotensin II is responsible for the psychotropic activity evoked by angiotensins in rats is thus confirmed.

Angiotensin I↗
PubMed1975

Effect of kinins on the central action of serotonin.

Kinins, the biologically active peptides, potentiate the central stimulatory effects of NA and depressant action of acetylcholine as have been shown by the authors previously. The aim of the work has been to study the effects of these peptides on the central action of 5-HT. For experiments female Wistar rats were used. 5-HT given ivc to the animals and 5-HTP applied ip resulted in an increase of the pain threshold to the electrical stimuli and in a worse motor coordination. Bradykinin injected ivc or kallikrein ip to some extent abolished these effects. The biochemical tests revealed that bradykinin ivc lead to a significant decrease in 5-HT content in the midbrain. In experiments in vitro this peptide increased markedly the release of the platelets 5-HT and inhibited the uptake of this mediator to platelets. The results have shown that kinins can attenuate the central action of 5-HT. This effect can be ascribed, at least in part to a kinin-induced changes of 5-HT concentration in some structures of the central nervous system.

5-Hydroxytryptophan↗
PubMedDate not supplied

Effect of angiotensin on the central action of dopamine.

Angiotensin given intraventricularly enhances amphetamine but not apomorphine-induced stereotypy 30 min. after peptide administration. Simultaneous injection of angiotensin and dopamine increases amphetamine -- while decreases apomorphine -- induced stereotypy. The stereotypy produced either by apomorphine or amphetamine in rats pretreated with Ro 4-4602 + L-DOPA was diminished by angiotensin. Angiotensin elevated haloperidol-induced catalepsy. A possibility that angiotensin may inhibit both release and uptake of dopamine by nerve endings is discussed.

Amphetamine↗
PubMedDate not supplied

Proteolysis in neuropeptide processing.

The paper reviews the functions of proteolytic enzymes in processing intracellular peptides. The enzymes may "activate" precursors of active peptides, "inactivate" active peptides by their degradation to biologically inactive forms, and "change" the peptides degrading biologically active forms to smaller peptides of different biological activity. The results of own studies on angiotensin II and its fragments are quoted to illustrate how various fragments of the peptide may display various biological activity.

Angiotensin II↗
PubMedDate not supplied

Lesions of central amygdala abolish angiotensin II improvement of recall in passive avoidance situation.

Our earlier experiments have shown that facilitating action of angiotensin II (AII) on recall of passive avoidance is mediated by dopaminergic systems. In an attempt to evaluate the possible site of action of AII on memory processes, bilateral lesions of the structures belonging to the limbic system, receiving efferentation from A 10 dopaminergic neurons were made before behavioral testing of the influence of intracerebroventricular (icv) AII injection on recall in a passive avoidance situation. Bilateral lesions of the nucleus centralis corporis amygdaloidei totally abolished the facilitating effect of AII on recall, while the lesions of the nucleus septi lateralis were ineffective. These results may suggest that improvement of recall in passive avoidance situation after icv injection of AII is mediated by A 10 dopaminergic neurons projecting to the central amygdala.

Amygdala↗
PubMedDate not supplied

Prostaglandins mediate some central effects of angiotensin II.

Pretreatment of rats with paracetamol (200 mg/kg po) abolished the enhancement of apomorphine and amphetamine stereotypy evoked by angiotensin II (0.5 microgram icv). The effect of angiotensin II was restored by an icv administration of 1 microgram of PGE1 X PGF2 alpha abolished the enhancement of stereotypy evoked by angiotensin II. PGE1 increased, while PGF2 alpha did not change the basic stereotypy induced by apomorphine and amphetamine. A specific radioimmunoassay of E-type prostaglandins (PGE1 + PGE2) revealed an increase by 136% in the level of PGE in the striata of rats pretreated with angiotensin II. These results suggest that stimulatory effects of angiotensin II in the central nigrostriatal system are, at least in part, mediated by the release of the E type of prostaglandins.

Acetaminophen↗
PubMedDate not supplied

Effect of angiotensin II on passive avoidance performance after bilateral lesion of the nucleus accumbens septi.

The experiments performed earlier in this Department indicated that facilitatory effect of angiotensin II (AII) on recall is connected with its influence on dopaminergic systems. In an attempt to evaluate the possible site of action of AII on the memory processes, bilateral lesion of the nucleus accumbens septi (NAS, a limbic structure which receives projection from A 10 dopaminergic neurons) was made before behavioral testing of the influence of icv injection of AII on recall in passive avoidance situation. Unexpectedly, bilateral lesion of the NAS improved the recall itself. In such a situation any facilitatory action of AII on recall in this test could not be shown.

Angiotensin II↗
PubMedDate not supplied

Psychotropic effects of angiotensin II N-terminal fragments: Asp-Arg-Val-Tyr-Ile-His and Arg-Val-Tyr-Ile-His in rats.

In this study the effects of angiotensin II (AII) angiotensin II hexapeptide [AII(1-6)] and angiotensin II pentapeptide [AII(2-6)] on the motility, stereotypy, learning of conditioned avoidance responses (CARs) and recall of a passive behavior making it possible to avoid aversive stimulation in rats, were compared. All the peptides were injected into the lateral cerebral ventricle (icv) in a dose of 1 nmol. AII caused a statistically significant increase in the number of crossings, rearings, and bar approaches in an open field whereas [AII(1-6)] and [AII(2-6)] were inactive in this test. The stereotypic behavior induced by an intraperitoneal (ip) injection of apomorphine (1 mg/kg) and amphetamine (7.5 mg/kg) was statistically significantly enhanced only in the rats which received AII icv. The application of AII, but not that of [AII(1-6)] and [AII(2-6)] resulted in a quicker acquisition of the CARs. A better recall of passive avoidance was achieved only by AII, while the fragments [AII(1-6)] and [AII(2-6)] had no effect. These findings indicate that the 1-6 and 2-6 fragments of AII do not possess a psychotropic activity like that of the parent octapeptide.

Amino Acid Sequence↗