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Biomedical subjects

R Drucker-Colín

Publications and source records attributed to R Drucker-Colín.

At least 73 records · Page 4Linked to original sources
PubMed1988

Microinjection of carbachol into the pontine area is unable to modify insomnia induced by p-cholorophenylalanine (PCPA).

It has previously been shown that cholinergic drugs administered into the pontine area (field tegmental gigantocellular, FTG) are capable of inducing significant increases of rapid eye movement (REM) sleep periods in normal cats. The purpose of this study was to determine whether such cholinergic stimulation is capable of inducing similar effects in p-chlorophenylalanine (PCPA) insomniac cats. Four groups (n = 6) of cats were used in this study. The first two groups received a microinjection of either, saline (1 microliter) or carbachol (8 micrograms/1 microliter). The last two groups, prior to the microinjection, received PCPA (400 mg/kg) pre-treatment. Histological analysis showed that the tips of the cannulae were located in the caudal FTG, at the level of the ponto-medullary union. Results showed that carbachol significantly increased REM sleep in normal cats as compared to saline, whereas, carbachol was unable to modify the insomnia induced by PCPA. These findings suggest that cholinergic effects on REM sleep require a serotoninergic system. The results are discussed in terms of acetylcholine/serotonin interaction in the control of REM sleep.

Animals↗
PubMed1988

Neuropsychological effects of brain autograft of adrenal medullary tissue for the treatment of Parkinson's disease.

We describe the pre- and postoperative neuropsychological profiles of seven patients who received an autograft of adrenal medullary tissue to the caudate nucleus for the treatment of Parkinson's Disease (PD). The preoperative neuropsychological evaluations revealed specific cognitive deficits of varying degree. The patients showed frontal lobe-type deficits with alterations in behavioral programming leading to difficulties in the organization of motor sequences and alternating programs. They also showed memory disorders and visuospatial and visuoperceptual deficiences such as a loss of figure-ground perspective and fragmentation. Postoperative evaluations, carried out 3 months after neurosurgery, revealed a significant amelioration of the frontal lobe-type symptoms and visuospatial deficits, as well as an improvement in memory tasks that require an active organization of the response. Immediate and delayed memory difficulties remained unchanged. These observations were compared to neuropsychological data obtained from neurologically intact subjects and from unoperated PD patients. The improvements of the operated PD patients resulted in performance levels close to normal values and clearly distinguishable from those of unoperated PD patients, and were unrelated to improved mood, increased alertness, or sustained attention. Autotransplantation of adrenal medullary tissue to the caudate nucleus of PD patients showing a decreased effective response to L-dopa therapy can partially restore motor functions and frontal-type cognitive symptoms.

Adrenal Medulla↗
PubMed1987

Transplantation of the fetal occipital cortex to the third ventricle of SCN-lesioned rats induces a diurnal rhythm in drinking behavior.

Fetal hypothalamic transplants which include the suprachiasmatic nuclei (SCN), were shown previously to be capable of restoring circadian rhythmicity as manifested by both diurnal and free-running rhythms in drinking behavior in rats rendered arrhythmic by SCN lesions. The question arises as to whether the transplant must be homologous tissue or whether any other fetal brain tissue can produce similar effects. In this study rats with a lesion of the SCN and with clear loss of drinking rhythms received grafts of fetal occipital cortex placed into the third ventricle. Following the graft, animals were placed in LD conditions for 8 weeks and then in DD for another 8 weeks. The results indicate that the cortical graft induced recovery of a drinking rhythm under LD lighting conditions but that under DD the rhythm was lost again. These results suggest that non-hypothalamic tissue can mediate recovery of a diurnal rhythm but that hypothalamic tissue including the SCN is required to restore circadian function with maintenance of free-running rhythms.

Animals↗
PubMed1987

Cerebroventricular infusion of cholecystokinin (CCK-8) restores REM sleep in parachlorophenylalanine (PCPA)-pretreated cats.

Recently, some studies have shown that cholecystokinin (CCK-8) administered either intraventricularly or intraperitoneally has no effect on sleep. However, since in such studies CCK-8 was given at times when sleep predominates, in this study the effects of CCK-8 on sleep were determined in parachlorophenylalanine (PCPA) (400 mg/kg)-pretreated insomniac cats. Twenty-four hours after the second injection of PCPA one group of cats received 100 ng/100 microliter of CCK-8 and another group only 100 microliter of saline. A third group was studied only under the effects of PCPA. The results showed that CCK-8 was capable of restoring sleep in the otherwise insomniac cats and that this effect was restricted to REM sleep only. The observed REM sleep-promoting action of CCK-8 supports the notion that this polypeptide may be involved in REM sleep regulation.

Animals↗
PubMed1987

Fetal brain transplants induce recuperation of taste aversion learning.

Rats showing disrupted taste aversion due to gustatory neocortex or amygdala lesions were transplanted into the lesioned area with homologous brain tissue obtained from 17-day-old fetuses. Comparisons of taste aversions scores before and after the graft, revealed that the grafted animals significantly recuperated taste aversions, whereas cortical lesioned animals without grafts did not. Surprisingly, however, amygdala-lesioned animals without graft presented spontaneous recovery. These results not only support the hypothesis that fetal brain transplants can restore cognitive functions, but also that there are some fundamental functional differences between the gustatory neocortex and the amygdala in the regulation of the processes involved in the acquisition and retention of taste aversion.

Amygdala↗
PubMed1987

Open microsurgical autograft of adrenal medulla to the right caudate nucleus in two patients with intractable Parkinson's disease.

Recent experimental studies and one clinical case have suggested that grafting tissue from the adrenal medulla into the brain may ameliorate the signs of Parkinson's disease. We describe the treatment of two young patients (35 and 39 years old) with intractable and incapacitating Parkinson's disease, in whom fragments of the adrenal medulla were autotransplanted to the right caudate nucleus. Clinical improvement was noted in both patients at 15 and 6 days (respectively) after implantation and has continued in both. Rigidity and akinesia had virtually disappeared in the first patient at 10 months after surgery, and his tremor was greatly reduced. A similar degree of improvement was present in the second patient at three months. We conclude that autografting of the adrenal medulla to the right caudate nucleus was associated with a marked improvement in the signs of Parkinson's disease in two patients, but our results are preliminary and further work is necessary to see whether this procedure will be applicable over the long term in other types of patients with Parkinson's disease.

Adrenal Medulla↗
PubMed1987

Rapid eye movement (REM) sleep and ponto-geniculo-occipital (PGO) spike density are increased by somatic stimulation.

It has been shown that REM sleep duration and ponto-geniculo-occipital (PGO) spike density can be enhanced by auditory stimulation. The purpose of this study was to determine whether this effect is restricted to the auditory sensory modality or whether somatic stimulation can produce similar effects. Cats implanted with electrodes for recording the sleep-wake cycle were additionally prepared with clip electrodes placed in the neck for somatic stimulation. Such stimulus was applied at the beginning and throughout each REM sleep period. The effect of this procedure was compared to a similar period when no stimulus was applied. The results showed that somatic stimulation induced a significant increase in REM duration (60.2%) and PGO spike density. Since the effects of somatic stimuli are identical to auditory ones, it is suggested that all sensory modalities may share the property of influencing the mechanisms which regulate the maintenance of REM sleep. Such mechanisms are discussed in terms of an increase in the excitability levels of polymodal medial reticular neurons.

Acoustic Stimulation↗
PubMed1986

Suprachiasmatic nucleus transplants function as an endogenous oscillator only in constant darkness.

Rats which sustained lesions of the suprachiasmatic nucleus (SCN) were transplanted with fetal hypothalamic tissue which included the SCN. After the graft, animals were kept under a 12:12 light-dark (LD) cycle during 6 weeks at which time half the animals were placed in constant light (LL) and half in constant darkness (DD). The results showed that all grafted rats recovered the photoperiod under LD, but under constant conditions rats began to free-run only in DD. The results suggest that the grafted tissue functions as a self-sustained oscillator only in darkness.

Animals↗
PubMed1986

Cholinergic reduction of REM sleep duration is reverted by auditory stimulation.

It was previously shown that an auditory stimulus given prior to and throughout a rapid eye movement (REM) sleep period was capable of inducing a significant increase in REM sleep duration and pontogeniculo-occipital (PGO) spike density. The purpose of this study was to determine whether the increase in REM duration is dependent on PGO spike density. We administered atropine to cats at doses of 0.1-0.6 mg/kg and the effects on REM duration and PGO spikes was determined. The doses of 0.2 and 0.3 mg/kg of atropine were then utilized to compare REM sleep periods with and without auditory stimulation. The results showed that both REM duration and PGO spikes were decreased by atropine, but could be dissociated from each other depending on the doses. In addition, it was shown that the auditory stimulus protected the animals from the effects of atropine but only in relation to REM sleep duration. The results indicate that both REM sleep duration and PGO spikes have a cholinergic component and that the auditory stimulus exerts its REM enhancing properties in a manner which seems to be independent of the PGO spike density. The results are discussed in terms of receptor availability and/or excitability levels of medial reticular neurons.

Acoustic Stimulation↗
PubMed1984

Fetal suprachiasmatic nucleus transplants: diurnal rhythm recovery of lesioned rats.

The diurnal rhythm organization of drinking behavior was determined prior to and after suprachiasmatic nucleus (SCN) lesions. Five weeks after SCN lesions which produced total loss of the diurnal rhythm, the anterior hypothalamus including the SCN of fetal rats was transplanted into the floor of the 3rd ventricle of the lesioned rats. Eight weeks after the graft, rats recovered their rhythm. The results show that grafts allow animals to recover lost functional properties due to lesions, and further support the notion that the SCN is a pacemaker for certain behaviors.

Animals↗
PubMed1984

Ultradian rhythm of pontomesencephalic opiate receptor: modification by chloramphenicol.

Pontomesencephalic receptor binding was measured in rats at 4-h intervals throughout a 24-h day. Two hours prior to each interval the animals were treated with either saline, thiamphenicol, or chloramphenicol. The results showed the existence of an ultradian rhythm of receptor binding. Such rhythm was abolished by chloramphenicol, but not by thiamphenicol. These results suggest that the number of available binding sites changes during a 24-h day, and that such availability is modified by chloramphenicol.

Animals↗
PubMed1983

Increasing PGO spike density by auditory stimulation increases the duration and decreases the latency of rapid eye movement (REM) sleep.

The purpose of this study was to determine whether ponto-geniculo-occipital (PGO) spikes play a role in triggering or maintaining sleep. During the recording of the sleep cycle of cats, the appearance of the first PGO spike automatically triggered an auditory stimulus through a speaker placed in the cat's recording cage. The effect of this procedure was compared to similar period when no such stimulus was given. The results showed that the auditory stimulus increased PGO spike density during REM sleep. It also produced a spectacular increase in the duration of REM, while decreasing the latency of its appearance from the first PGO spike. It is suggested that the auditory stimulus reinforces the 'PGO system', which in turn may function as a pace-setter for priming and maintaining REM sleep.

Acoustic Stimulation↗
PubMed1983

Kainic acid lesions of gigantocellular tegmental field (FTG) neurons does not abolish REM sleep.

This study attempts to resolve questions concerning the cholinergic mediation of REM sleep by FTG cells. The sleep-wake cycle of cats with bilateral kainic acid destruction of FTG cells, was followed for 2 months. At the end of this period carbachol was applied unilaterally on the lesioned site. The results showed no changes in REM despite the absence of FTG cells. No changes were observed following carbachol administration. This study shows that FTG cells are not essential for REM sleep, but that in non-lesioned cats its cholinergic activation may form part of a complex REM generating system.

Acetylcholine↗
PubMed1983

Dissociation of rapid eye movement (REM) sleep features: possible implications for REM triggering mechanisms.

Neurophysiological and biochemical mechanisms regulating REM sleep episodes were studied in behaving cats with chronic electrodes. Push-pull perfusion of the midbrain or pontine reticular formation (RF) by a protein synthesis inhibitor, chloramphenicol (CAP), reduced neuronal unit discharge, particularly discharge bursts, within the perfused area, and reduced the incidence of sustained REM periods. During transitions to "aborted" as compared to sustained REM episodes. RF unit discharge was reduced, under all conditions. In 72-hour sleep deprived cats, systemic injections of both atropine (ATR) and CAP attenuated REM rebound, but with different patterns. CAP reduced REM episode frequency. ATR reduced REM duration. ATR also reduced PGO wave frequency. Combined CAP and ATR treatment produced additive REM depressant effects. These data suggest that cholinergic mechanisms regulate PGO activity and maintenance of REM episodes and that protein synthesis-dependent mechanisms regulate RF unit discharge bursts, and REM triggering.

Animals↗
PubMed1982

Sleep and medial reticular unit responses to protein synthesis inhibitors: effects of chloramphenicol and thiamphenicol.

This study utilized a newly developed combination push-pull cannula/microdrive-microwire device to record single-unit activity within the diffusion field of substances introduced into the brainstem. Single unit activity within the midbrain and pontine medial reticular formation (RF) and sleep were recorded following either perfusion or oral administration of protein synthesis inhibitors, chloramphenicol and thiamphenicol. Chloramphenicol administration led to significant reductions in the frequency, but not the duration, of individual REM episodes without altering slow-wave sleep. During control experiments in slow-wave sleep, incipient REM was characterized by substantial increases in medial RF unit activity which occurred in association with the appearance of PGO spikes. On the other hand, discharge rates of medial RF neurons were markedly attenuated by chloramphenicol but were not consistently affected by thiamphenicol. These findings suggest that reduced unit activity contributes to the REM-suppressive effects of protein synthesis inhibitors.

Animals↗