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Biomedical subjects

V Tamásy

Publications and source records attributed to V Tamásy.

15 recordsLinked to original sources
PubMed1984

Suckling ability and maternal prolactin levels in hypothyroid rats.

Long-Evans rats and their offspring were made hypothyroid by addition of the antithyroid goitrogen 6-N-propylthiouracil (PTU) to the drinking water (0.1%) from the day of parturition. Serum concentrations of prolactin (PRL), thyroid-stimulating hormone (TSH) and thyroxine (T4) were determined by double radioimmunoassay (RIA). From the fifth postnatal day, body weight of PTU-treated pups was significantly lower than that of control rats, and a strikingly elevated serum TSH level and nondetectable amount of T4 were measured both in PTU-exposed mothers and their offspring at Day 10 postpartum. To test the youngs' suckling capability and the amount of maternal milk production, 10- and 15-day-old normal and PTU-treated pups were separated from their mothers for 4 hr in the morning and then reunited and allowed to suckle. Normal pups gained body weight at the end of both the first and second hour postreunion, while PTU pups gained only during the first hour and lost weight in the second hour of testing. When the pups were exchanged between normal and PTU mothers, opposite results were obtained, indicating that the reduced gain in hypothyroid rats was not due to impaired suckling capability, or insufficient sensory stimulation for milk secretion but to a decreased milk production of PTU mothers. In accordance with this, in lactating hypothyroid rats both the basal (presuckling) level and the suckling-induced rise of serum PRL were found significantly depressed.

Animals↗
PubMed1983

Steroid anaesthesia: alphadione depresses multiunit activity in the mesencephalic reticular formation.

Cortical EEG and multiunit activity (MUA) of the mesencephalic reticular formation (MRF), area hypothalami anterior (AH) and the nucleus amygdalae basalis (AMY) were studied before and after different doses of alphadione (Althesin) and hexobarbitone (Evipan-Natrium) given to cats with chronically implanted electrodes. Non-anaesthetic doses of alphadione (0.15 ml/kg; 0.3 ml/kg; 0.6 ml/kg and 1.2 ml/kg i.p.) had sedative effects decreasing selectively the MUA in the MRF. In doses of 2.0 ml/kg, 2.4 ml/kg and 3.0 ml/kg i.p., alphadione induced anaesthesia which was associated with a rapid decrease of MUA in the MRF and by a gradual decrease of activity in the AH and AMY. The i.p. dose of 3.0 ml/kg abolished MUA responses of the reticular formation to acoustic, visual and somatic stimulation but failed to block responses to pain. Deep anaesthesia with lasting analgesia could be maintained by i.v. infusion (0.075 ml/kg/min). This procedure blocked the responsiveness to painful stimulation while pharyngeal and laryngeal reflexes were maintained. Hexobarbitone in a dose of 20.0 mg/kg i.p. did not produce anaesthesia in the cat. Administration of 40.0 mg/kg i.p. resulted in a rapid decrease of MUA in the MRF, AH and AMY, MUA responses to each stimulation were abolished and the pharyngeal reflex was blocked.

Alfaxalone Alfadolone Mixture↗
PubMed1982

Brain catecholamine concentration during the first week of development in rats.

Neonatal brain (whole brain minus cerebral hemispheres) dopamine (DA) and norepinephrine (NE) concentrations (pg/microgram protein) were studied 30 min after an injection of L-DOPA methyl ester (50 mg/kg); haloperidol (1 mg/kg); D-amphetamine sulfate (0.5 mg/kg); saline only or no treatment. Catecholamines were assayed on the day of birth (postnatal day 1) and postnatal day 7 by high performance liquid chromatography coupled with an electrochemical detector for catecholamines (CA). When L-DOPA was administered there was a selective 7 X (postnatal day 1) or 3 X (day 7) increase in brain DA when compared to saline controls. Haloperidol pretreatment on either day prevented these increases after L-DOPA. These findings constitute biochemical evidence for selective elevation of brain DA during the first postnatal week of life after L-DOPA administration in a dosage that is also capable of enhancing the coordination required for swimming behavior.

Animals↗
PubMed1981

The role of dopaminergic and serotonergic mechanisms in the development of swimming ability of young rats.

Neonatal swimming behavior was studied after a single subcutaneous injection of L-dopa methyl ester (50 mg/kg; 200 mg/kg) apomorphine (0.1 mg/kg; 1.0 mg/kg), DL-amphetamine (0.5 mg/kg; 10 mg/kg), haloperidol (0.5 mg/kg; 1.0 mg/kg), L-tryptophan (50 mg/kg; 100 mg/kg), methysergide (1.0 mg/kg; 5.0 mg/kg) as well as intraventricular injection of 100 microgram 6-OHDA. 1-, 3-, 5- and 7-day-old rats were placed into a temperature-controlled aquarium (37 degrees C) and the pattern of motor coordination, latency time to swimming (LTS) and the number of foreleg strokes for 10 s (FS) were measured. When compared to the physiological saline-injected controls, rats that received L-dopa showed a striking increase of FS at all ages but the most striking improvement of motor coordination was found in newborn rats. On day 1 both doses of DL-amphetamine induced increases in FS and improvement of motor coordination, whereas apomorphine failed to show any effect at this age. On days 3, 5 and 7 low doses of DL-amphetamine and apomorphine increased the FS. However, high doses resulted in a decrement in swimming performance. Haloperidol impaired swimming on day 1 but produced a significant increase of FS on days 5 and 7. Neonatal injection of 6-OHDA delayed development of motor coordination, reduced FS and increased LTS. On days 3, 5 and 7 high doses of L-tryptophan elicited an increase of FS, while high doses of methysergide caused significant impairment of performance. It is suggested that the brain rapidly converts the administered L-dopa to dopamine during the first week of life and there appears to be a strong dependent relationship between the pattern of motor coordination and the amount of available dopamine in the developing brain.

Age Factors↗
PubMed1980

Early postnatal development of wakefulness-sleep cycle and neuronal responsiveness: a multiunit activity study on freely moving newborn rat.

The development of the wakefulness-sleep cycle and neuronal responsiveness was studied on freely moving 1-, 3-, 5- and 7-day-old rats. Semimicroelectrodes were implanted under ether anaesthesia for multiunit activity (MUA) recording from the mesencephalic reticular formation (MRF) and basal forebrain area (FB). Following recovery from surgery and between the recording sessions pups were put back to the nest to be fed by their mothers. In a temperature-controlled environment continous MUA records were made between 16:00-18:00 and 19:00-21:00 h. In the MRF and FB the MUA was high during wakefulness, it decreased to a stable low level in quiet sleep and appeared to reach the highest values in paradoxical sleep. Neurone populations in the MRF and FB responded to somatosensory (air puffs), visual (flicker) and acoustic (1100 Hz) stimulation by a significant increase of MUA from the first day of life. In the MRF the rate of responsiveness increased during the first postnatal week; however, MUA responses to different stimuli exhibited different developmental time-courses. A high rate of responsiveness to each stimulus was characteristic of FB units. This neonatal 'supersensitivity' tended to decrease with age and the time-course of developmental changes proved to be modality-dependent.

Acoustic Stimulation↗
PubMed1980

Multiunits in the mesencephalic reticular formation: ontogenetic development of wakefulness and sleep cycle in the rat.

Recording of multiunit activity (MUA) from the mesencephalic reticular formation (MRF) of freely behaving rats, aged between 1 and 120 days, revealed that state dependent changes in cell firing associated with wakefulness and sleep cycle were present from the first day of life. The MRF neuron populations were found to gain the adult-like functional properties by the 9-11th postnatal day. The paradoxical sleep phases attained adult characteristics by day 12-13 and the average duration of slow wave sleep episodes was that of adult rats at the end of the 4th week, the maturation of sleep behavior was completed at the age of day 33-35.

Animals↗
PubMed1980

The developing mesencephalic reticular formation: changes in responsiveness during ontogeny of the rat.

Multiunit activity (MUA) of the mesencephalic reticular formation (MRF) was recorded on freely moving 1 to 21-days-old young as well as adult rats. Consistent state-dependent changes in the frequency of amplitude discriminated cell discharges were observed in association with wakefulness and sleep cycle from the first day of life, and MRF neuron populations were found to gain adult-like functional characteristics of spontaneous activity by the 9th-11th postnatal day. MRF units were capable of responding to somatosensory, visual and acoustic stimulation by a significant activation from Day 1. As development proceeded, rate of responsiveness appeared to increase, however, MUA responses to different sensory modalities exhibited different developmental time-courses. High rate of responsiveness to somatosensory stimulation was characteristic of the newborn rat. Magnitude of somatosensory responses increased remarkably during the first three postnatal days reaching adult values around this age and only moderate alteration of response patterns could be detected afterwards. The MRF MUA responses to visual and acoustic stimulation increased during the first week of life and, following a striking decline of responsiveness occurring at the time of opening of eyes and external auditory meati (Day 13), visual and acoustic responses gained the adult properties by the 17th-19th postnatal day.

Aging↗
PubMed1976

Effect of thyrotropin-releasing hormone (TRH) and antidepressant agents on brain stem and hypothalamic multiple unit activity in the cat.

The EEG and MUA (multiple unit activity) of mesencephalic reticular formation (MRF), area hypothalami posterior (PH), and area hypothalami anterior (AH) were studied in chronically implanted freely moving cats. The effects of thyrotropin-releasing hormone (TRH) and some antidepressant agents were tested on neuronal activity. Desipramine and imipramine resulted in a dose-dependent decline of MUA of all structures with the most significant decrease of activity in PH. A single injection of TRH resulted in slight or moderate gross behavioral changes and vegetative excitation lasting for 30-50 min with variable MUA levels. In the course of repetitive TRH treatment on consecutive days the gross behavioral changes and the vegetative symptoms failed to develop by the 3rd or 4th day. By that time the MUA changes of PH and MRF showed similar characteristics in response to TRH administration which was observed following the injection of desipramine and imipramine. The drugs, except for TRH, induced a suppression of paradoxical sleep cycles.

Animals↗
PubMed1975

Multiple unit activity study of brain stem and limbic structures during environmental habituation and circadian rhythm.

Multiple unit activity (MUA) of brain stem, hypothalamic and limbic structures was studied during habituation to a novel environment and circadian rhythm in chronically implanted freely moving rats. MUA was analysed in the mesencephalic reticular formation (MRF), area hypothalami posterior (PH), basal nuclear group of amygdala (AMY), area septalis (SEPT), dorsal hippocampus (HIPP) and area hypothalami anterior (AH). It was found that in the novel environment MUA of all subcortical structures increased to a high level. During habituation MUA in each phase of wakefulness--sleep cycle decreased to stable low level both in brain stem and forebrain structures. Gradual decrease in MUA was characteristic to MRF, and a sharp decrease occured in AH and AMY. The environmental habituation proved to be a long lasting process in rat. During all phases of wakefulness--sleep cycle activity was significantly higher in the light period than in the dark, and MUA base level showed circadian variation both in brainstem and limbic structures. Close correlation was found between the actual MUA level and responsiveness to various sensory modalities both during habituation and circadian rhythm. The higher the MUA level, the higher the responsiveness, and a fall in activity was accompanied by decreased neuronal responsiveness.

Amygdala↗
PubMed1975

E.E.G. and multiple unit activity during ketamine and barbiturate anaesthesia.

Cortical e.e.g. and multiple unit activity (m.u.a.) of the mesencephalic reticular formation, the anterior hypothalamic area, the basal nuclear group of the amygdala and the dorsal hippocampus were studied before and following i.p. injection of different doses of ketamine hydrochloride and a barbiturate in cats with chronically implanted electrodes. Barbiturate administration resulted in a rapid decrease in m.u.a. in the mesencephalic reticular formation which was accompanied by a significant decrease of activity in the limbic structures. No m.u.a. response was observed to visual, acoutic or somatosensory stimulation or to pain. The m.u.a. of the mesencephalic reticular formation and limbic structures increased gradually following ketamine injection. Intermittent or continuous hypersynchronous activity was characteristic in the cortical e.e.g. During the hypersynchronous activity the responsiveness of m.u.a. in the mesencephalic reticular formation, to visual and acoustic stimuli, was blocked. Somatosensory and painful stimulation, however, resulted in a significant increase in the activity both of the mesencephalic reticular formation and of the limbic neuronal pools.

Acoustic Stimulation↗