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Biomedical subjects

N E Chepurnova

Publications and source records attributed to N E Chepurnova.

At least 19 recordsLinked to original sources
PubMed2002

[Pregnancy in WAG/Rij rats--changes in the levels of progesterone, estradiol and generalized absence epilepsy].

Progesterone and oestradiol serum level was investigated in WAG/Rij rats with genetically determined absences. Blood samples were drawn before and after the pregnancy following the parturition. The serum concentration of progesterone increased after the 3rd day of pregnancy. There is no increasing of oestradiol during pregnancy as large as this. The progesterone is kept high to the 18th day of pregnancy and drastically decreased before the parturition. Common duration of absences--spontaneous spikewave discharges (SWD), frequency and the duration of every SWD decreased from 3rd to 19th days of pregnancy before the parturition. On the basis of these data and modern investigations, regulation of GABAA receptor expression during pregnancy by progesterone (Brusaartd A. B. et al., 1999) it can be assumed that the changes in the parameters of SWD are possibly correlated with the progesterone changes in serum during pregnancy in WAG/Rij rats.

Animals↗
PubMed2001

PTZ-induced seizures in rats: effects of age and strain.

The susceptibility to pentylenetetrazol (PTZ)-induced seizures during postnatal ontogeny [postnatal day (PN) 10-220] was investigated in two rat strains. The WAG/Rij strain, genetically prone for developing generalized absence epilepsy, and Wistar rats were tested and compared at PN 10, 26, 30, 70, 90, 125, and 220 on the PTZ-convulsive threshold. A subconvulsive dose of 25-mg/kg PTZ was administered every 15 min, and the occurrence of clonic and tonic-clonic seizures was scored. The 10-day-old pups were quite sensitive to PTZ and showed mainly clonic seizures. The highest threshold and latency of PTZ-induced clonic and tonic-clonic convulsions were observed at PN 26 in both strains. From that age onwards, the seizure threshold significantly decreased and reached a minimum at PN 220. Between strain comparisons showed that WAG/Rij rats have a lower tonic-clonic seizure threshold than Wistar rats. The data indicate that changes in susceptibility first quickly decreases until PN 26-30 and then tend to monotonically increase with age, and that genetically prone nonconvulsive WAG/Rij rats are more vulnerable to convulsive seizures induced by PTZ than Wistar rats.

Aging↗
PubMed2001

[Peptidergic mechanisms of hypothermia-induced seizures in rats during early ontogenesis].

Arginine-vasopressin reduced the tonic-clonic seizures' latency as well as the duration of the seizures brain-stem generalisation on the 3rd and 5th postpartum days in rats. The reduced latency was also observed after the PACAP38 low doses administration, whereas higher doses diminished and then enhanced the threshold of generalised hyperthermia-induced seizures on the 3rd and 5th days and the 7th and 9th days, resp. The arginine-vasopressin-treated animals had a dramatically enhanced duration of the tonic-clonic seizures up to the epileptic status on the 9th postpartum day. The findings suggest the PACAP involvement in mechanisms of experimental febrile seizures through its effect upon arginine-vasopressin neurosecretion.

Animals↗
PubMed2000

New aspects of heparin effects.

The effects of a 5-day heparin treatment (10 kD, 64 IU/kg, intraperitoneally) on food-procuring behavior and spatial memory in a 12-arm radial maze were studies on Wistar rats. The maximum reinforcement scores in heparinized rats were attained by day 7 and in control rats only by day 16. In total, 75% heparinized and 45% control rats successfully learned the task for 24 days. On day 25 the contents of major transmitters and their metabolites in various brain structures and in the small intestine of control and experimental rats were determined. The rats treated with heparin showed increased concentrations of norepinephrine in the hypothalamus, homovanillic acid in the striatum, and serotonin in the small intestine. Our findings indicate that heparin exhibits a wide range of activities in addition to its anticoagulant effect.

Animals↗
PubMed1994

[The lateralized effects of the melanostatin analog alaptide in rats raised in isolation and in a community].

Effects of alaptide on self-stimulation of the lateral hypothalamus, rotation behaviour and learning ability were studied in rats growing either in social adaptation or in groups. The effects on self-stimulation were opposite in these rats. Alaptide facilitated the learning process in grouped rats and potentiated the indirect dophamine-mimetic action of amphetamine in isolated rats.

Amphetamine↗
PubMed1992

[Thyroliberin: new physiological effects and prospects of clinical use].

In addition to the well-known activities of TRH (stimulation of respiration, antidepressant action, increase of motility, antishock action, therapeutic effects against ataxia, and so forth), some new properties were established. TRH was found (1) to stimulate the contractility of lymph vessels in ultra-low doses and to be useful in the treatment of acute pancreatitis; (2) to normalize cerebral circulation in rats and neonates after asphyxia; (3) to improve the electrophysiological parameters of the retina and pigmented epithelium in rats and man, to exert a long-term positive influence on the health status of patients suffering from senile retinal macular dystrophy; (4) to potentiate the analgesic effect of low doses of morphine in a definite range of doses (analog PR-546). It is of paramount importance that most of the indicated activities of TRH may hold promise for clinical application.

Acute Disease↗
PubMed1991

[An increase in brain temperature in rats to the intranasal administration of thyroliberin].

The integral rat brain temperature was measured by radiothermoscope after intranasal instillation of thyroliberin in a dose 400 mkg. The recording increase of temperature lasted during two hours after instillation. This phenomenon is based both on the direct action of thyroliberin and on its capacity to stimulate the induction of other regulatory peptides.

Administration, Intranasal↗
PubMed1989

[Thyroliberin-induced motor asymmetry as an indicator of the individual behavioral strategy of rats in a radial labyrinth].

The individual peculiarities of functional changes in motor asymmetry determined by behavioral test in T-maze have been shown in experiments with rats (nonpedigree and line LATI). The application of thyroliberin (10 mkg/kg) causes and increases the left-side lateralization which introduces alteration in the individual strategy of the successive round of 12 rays of radial maze with food during solution of spatial orientation task.

Animals↗
PubMed1989

[Comparison of the effects of thyroliberin and ACTH4-7 PGP on the learning of rats during the solving of spatial orientation tasks].

The influence of TRH (100 micrograms/kg) and ACTH4-7 Pro-Gly-Pro (15 micrograms/kg and 25 micrograms/kg) involved an acceleration of the spatial learning on the 12-arm radial maze and on T-maze in rats; an increase in the number of correct choice after short (5-10 min) retention interval; and affected the working and reference spatial memory in the test of reinforced place performance. The effects of the TRH and ACTH4-7 Pro-Gly-Pro did not interfere with one another.

Adrenocorticotropic Hormone↗
PubMed1989

[Anticonvulsive properties of peptide ACTH4-7 pro-gly-pro detected in amygdaloid kindling and audiogenic epilepsy in rats].

Effects of the ACTH4-7 pro-gly-pro, calcium valproate ("Germed", DDR) and nembutal on kindling preparation and audiogenic epilepsy were investigated. Development of after-discharges in response to repeated amygdaloid electrical stimulation was assessed in normal rats and in rats susceptible to audiogenic epilepsy (KM line of rats). ACTH4-7 pro-gly-pro had an anticonvulsant profile. ACTH4-7 pro-gly-pro decreased seizure threshold in the audiogenic epilepsy test, but did not prevent the motor convulsions.

Acoustic Stimulation↗
PubMed1985

[Central action of melanostatin and the opiate system of the brain].

The effects of intraventricular administration of melanostatin (MIF--I, Pro--Ley--Gly--NH2) on the behaviour and electrical activity in neocortex, amygdala, hippocampus and hypothalamus involved an enhancement of electrical activity: MIF enhanced the 3--7/sec high--voltage activity of neocortex, amygdala, hippocampus and the 7--12/sec one of neocortex. Morphine facilitated the effects of MIF whereas preliminary administration of MIF blocked the effect of threshold doses of morphine. After lesion of the central nucleus of amygdala the responsiveness of ipsilateral neocortex disappeared whereas that of hippocampus preserved.

Animals↗
PubMed1984

[Efferent sympathetic activity after stimulation of the amygdaloid nuclei of the rat brain].

Efferent sympathetic activity (ESA) recorded from cervical sympathetic trunk, was augmented after stimulation of medial, cortical and basal amygdaloid nuclei, whereas stimulation of the lateral amygdaloid nuclei decreased the ESA. Stimulation of the dorsal hippocampus also decreased the ESA. Electrolytic lesion of the septum led to an increase of the ESA during simultaneous stimulation of the lateral amygdaloid nucleus and the dorsal hippocampus. The data suggest that functional interaction between amygdaloid nuclei and septal relays participate in the amygdaloid influence on the activity of preganglionic sympathetic neurons.

Amygdala↗
PubMed1984

[Reactions of neurons of the anteromedial hypothalamus to microiontophoretic administration of luliberin].

The effects of microiontophoretic application of luliberin (LHRH), norepinephrine (NEO) and morphine on activity of the medial preoptic hypothalamic neurons were studied in male rabbits. About 80% of all the neurons responded to LHRH, mainly with facilitation. NEO appeared to have inhibitory influence on the LHRH-induced effects, when LHRH was applied simultaneously with NEO. Since the LHRH effect might be mediated via opiate receptors, it was examined against the background of morphine application. LHRH applied after morphine increased the number of unresponsive units. During simultaneous application of LHRH and morphine the number of unresponsive units increased by 30% and the number of facilitation responses decreased to 30% of the neurons under study. These findings confirm that the opiate receptors and noradrenergic system play a certain role in the central effects of LHRH.

Animals↗