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F Mora

Publications and source records attributed to F Mora.

At least 127 records · Page 7Linked to original sources
PubMed1986

Effects of agonists and antagonists of cholinergic receptors on self-stimulation of the medial prefrontal cortex of the rat.

The effects of agonists and antagonists of muscarinic and nicotinic receptors on self-stimulation (SS) of the medial prefrontal cortex (MPC) were investigated. Rats, implanted chronically with monopolar electrodes in the MPC, received subcutaneous injections of nicotine (0.2, 0.4 and 0.8 mg/kg), mecamylamine (2.0, 4.0 and 8.0 mg/kg), pilocarpine (0.5, 1.0, 2.0 and 4.0 mg/kg), scopolamine (0.05, 0.1, 0.2, 0.4 and 0.8 mg/kg) and physostigmine (0.1, 0.2 and 0.4 mg/kg). In order to assess the possible non-specific effects of drugs such as sedation or motor dysfunction, spontaneous locomotor activity (SLA) was used as control. In those groups of rats in which the drugs produced an effect on SS, an operant behaviour for drinking (DB) on an FR-10 schedule was also used as control. Nicotine and mecamylamine had no effect on SS. Both pilocarpine and physostigmine produced a decrease in SS, SLA and DB. Scopolamine, on the contrary, produced a dose-related decrease on SS rate, which was accompanied by a facilitatory effect on SLA and DB. These results suggest that only muscarinic receptors could play a specific role on SS of the MPC.

Acetylcholine↗
PubMed1986

Adipsia-polydipsia induced by simultaneous lesion of the medioventral septum and anteroventral third ventricle area in the rat.

The medioventral septal area (MVS) and also the tissue surrounding the periventricular preoptic-hypothalamic region (AV3V) of male rats, were destroyed by mean of electrolytic lesions. Before and after the lesions, daily water and food intakes, diuresis, body weight, urine osmolarity, and sodium and potassium excretion were determined. Rats with simultaneous AV3V-MVS lesions showed a biphasic pattern of drinking behavior characterized by a first period of adipsia followed by another period of polydipsia. During the first period of adipsia and except for the first two days, postlesion rats were able to reduce total urine volume but failed to produce an appropriate concentrated urine. During the polydipsia period, on the contrary, rats increased urine output and decreased urine osmolarity in a parallel fashion. Immediately after the lesion, food intake was decreased but recovered to pre-lesion levels gradually. By contrast, body weight was decreased during the entire period of the experiment. Sodium but not potassium excretion showed a significant increase from the 9th to the 20th day postlesion. The results suggest that the AV3V and MVS are part of a circuitry subserving the control of water intake and electrolyte balance.

Animals↗
PubMed1986

Motor activity of esophageal substitute (stomach, jejunal, and colon segments).

Manometric studies were performed to evaluate motor activity of several types of esophageal substitutes: total stomach (5 patients), isoperistaltic gastric tube (5 patients), jejunal Roux-en-Y loops (4 patients), and isoperistaltic left colon (15 patients). Motor behavior of substitutes was assessed following dry swallows and following several stimuli: intraluminar injection of 30 ml of water or 0.1N hydrochloric acid and swallowing pills. Following dry swallows, there was no response with either stomach or isoperistaltic gastric tube, jejunum showed a variable response, and a response was infrequent in patients with colon transplants. After dry swallows, transmission of the pressure wave through the anastomosis was not observed in any patient. Total stomach and isoperistaltic gastric tube did not respond to any stimulus. Jejunum responded with progressive waves after water and solid stimuli, and had a hyperkinetic response after acid injection. Colon had a constant (80 to 90%) and homogeneous response with progressive waves after all stimuli. After wet swallows, there was transmission through the anastomosis in 2 patients with colon transplants. Our data indicate that stomach and isoperistaltic gastric tubes do not contribute actively to the onward transmission of food in the digestive tract. Jejunum may contribute actively in digestive transit, but its responses are variable. Having steady and homogeneous responses, colon segments take an active part in transit.

Adolescent↗
PubMed1986

Glutamic acid as a putative transmitter of the interhemispheric corticocortical connections in the rat.

The effect of hemidecortication on the endogenous levels of amino acids in medial, sulcal, and dorsal frontal cortex as well as in parietal, temporal, and occipital cortex of the rat was investigated. Under aseptic conditions, the right cerebral cortex was aspirated by suction. Then, 21 days later, the content of glutamic acid, aspartic acid, gamma-aminobutyric acid, glycine, serine, threonine, and alanine was analyzed in six areas of the intact contralateral cortex using GLC. The results demonstrated a specific decrease in the endogenous levels of glutamic acid in both parietal and temporal cortex after hemidecortication of the contralateral side. This finding suggests that glutamic acid may serve as a neurotransmitter for some of the interhemispheric corticoparietal and corticotemporal fibers. In a follow-up experiment, the effect of a frontal lesion on the endogenous levels of the same amino acids in the striatum was also examined. In this case, the glutamic acid content exhibited a decrease of 31% relative to the control value. This observation confirms the earlier finding of a glutamate-containing pathway from the frontal cortex to the striatum.

Alanine↗
PubMed1986

New method for quantitative evaluation of esophageal sensibility.

A method for quantitating esophagus sensibility by an electric stimulation test is described. Square stimulus waveform at different voltages and durations were transmitted to the esophagus, three series of electric stimuli being used in successive durations (0.5, 1, 2, 4, 8 and 16 ms); in each series the voltage discharge was increased progressively from 0 mV, until the subject noted the first sensation. This procedure was carried out at all esophageal levels. The following parameters were analyzed: sensitive threshold along the esophagus; the relation of threshold sensibility (mV) duration of stimulus (ms), and reobase and cronaxia for each esophageal level. At all esophageal levels, the sensitive threshold was regular and coherent; in the middle esophagus a zone was found having higher sensitive threshold than the proximal and distal esophageal zones. The relationship between sensitive threshold and inverse of the stimulus duration indicated that esophageal sensibility follows the basic law of excitation of WEISS, at least with this type of stimulus, reobase and cronaxia being representative of the sensibility threshold along the esophagus. Quantitative esophageal sensibility, therefore is concluded to be particularly suited to evaluation by electric stimulation.

Adolescent↗
PubMed1985

Dopamine and thermoregulation: an evaluation with special reference to dopaminergic pathways.

The complex role of dopamine (DA) in the diencephalic mechanisms involved in the control of body temperature is reviewed and evaluated. In the context of the monoamine theory of thermoregulation, catecholaminergic synapses in the anterior hypothalamic pre-optic area, are proposed mediate the pathways in the brain-stem which subserve heat dissipation. Within this theoretical framework, hypothalamic DA is considered to underlie a portion of the functional component of the heat loss system. This deduction is based on pharmacological studies in which both the catecholamine and receptor antagonists have been infused directly into the hypothalamus. In view of the action of DA applied to the substantia nigra and other subcortical structures, the unique anatomical circuitry of the central dopaminergic projections has also been analyzed in terms of specific connections within critical morphological regions related to thermal functions. In particular, the nigro-striatal pathway could be involved in the mediation of one or more of the different aspects of the thermoregulatory system integrating both autonomic and behavioral responses. Finally, an anatomical schema which portrays the suggested mechanisms of DA activity is presented.

Animals↗
PubMed1985

Suppression of self-stimulation of the medial prefrontal cortex after local micro-injection of kainic acid in the rat.

The question of whether neurons versus fibers of passage in the medial prefrontal cortex (MPC) are essential in maintaining self-stimulation of this same area of the brain was examined. Rats were prepared with electrode-guide cannulae implanted stereotaxically to rest within MPC. A micro-injection of (KA), 10 nmol/1.0 microliter, into the right MPC produced a clear degeneration of neuronal cell bodies characterized by picnocytosis and glial invasion of the tissue surrounding the tip of the electrode. These histopathological changes were correlated with a permanent abolition of self-stimulation of the right MPC. In contrast, self-stimulation of the contralateral side of the MPC, micro-injected with 0.9% NaCl vehicle as a control, was unaffected. These results suggest that neurons of the MPC are part of the neural substrate underlying self-stimulation behavior in this cortical area of the rat.

Animals↗
PubMed1985

Total fundoplication with or without gastroplasty for gastroesophageal reflux: comparative study.

The results of clinical, radiographic, manometric, and pH-metric studies of two groups of patients with reflux esophagitis treated by total (Nissen) fundoplication with or without a Collis esophagus-lengthening gastroplasty were compared. On postoperative follow-up, clinical recurrence of gastrophageal reflux was found in 5 of the 76 patients in the Nissen group, whereas none of the 46 patients in the Collis-Nissen group had reflux. A dramatic reduction in the clinical score was observed for all patients, and postoperative clinical morbidity was similar in both groups. Postoperative radiographic recurrence of hiatal hernia was found in 11 of 60 patients in the Nissen group, but not in any of the patients in the Collis-Nissen group. The lower esophageal sphincter pressure was significantly increased after operation in both groups (p less than 0.05). The postoperative "common cavity test" and acid reflux test were positive in 9% of the patients having Nissen fundoplication alone and 11% of those having the Collis-Nissen procedure; in the latter group, both tests were positive in only 1 asymptomatic patient. These results demonstrate that the standard Nissen repair is a good surgical technique for management of uncomplicated reflux esophagitis and that the Collis-Nissen procedure is the most effective method of surgical repair for almost all patients with complicated reflux esophagitis.

Adolescent↗
PubMed1985

Effect of intracerebroventricular vasopressin on body temperature and endotoxin fever of macaque monkey.

In the adult monkey (Macaca fasicularis) acclimated to a primate restraint chair, intracerebroventricular (ICV) cannulas were stereotaxically implanted bilaterally in the lateral cerebral ventricle. During an experiment, colonic and skin temperatures were continuously recorded, and in selected cases heart and respiratory rates as well as O2 consumption were similarly monitored. Arginine vasopressin (AVP) was infused ICV in a volume of 500 microliter in one of six doses ranging from 16 to 4,240 ng. The results showed that AVP in all doses infused failed to alter the resting core and skin temperatures of the monkey or other recorded physiological responses. After a fever was produced in the monkey by 1/10-1/100 dilution of Escherichia coli endotoxin infused ICV, AVP at doses of 16-260 ng did not augment the febrile response. Further, AVP infused in the same range of doses caused only a negligible and inconsistent antipyretic action; i.e., the 65-ng dose of AVP lowered the mean core temperature of the febrile monkey by only 0.5 degrees C. This was in marked contrast to the antipyretic effect of dipyrone administered systemically. In addition, no reproducible changes occurred in respiratory, heart, or metabolic rates after ICV infusion of AVP. These results indicate that AVP does not affect the normal thermoregulatory function of this species of monkey and, in contrast to other species, a febrile response is neither enhanced nor antagonized in the monkey by a central action of AVP. Although AVP thus does not appear to be an endogenous antipyretic in the monkey, anatomic investigations will be required to substantiate this conclusion in the subhuman primate.

Animals↗
PubMed1984

Opioid peptides and self-stimulation of the medial prefrontal cortex in the rat.

The possible involvement of opioid peptides as part of the neurochemical substrates of self-stimulation (SS) in the medial prefrontal cortex (MPC) of the rat was investigated in two different groups of rats bilaterally implanted with monopolar electrodes in the MPC. In the first group, morphine (5, 10, and 20 micrograms) and an enkephalin analogue (BW 180) (5, 10, 20 and 40 micrograms) were injected through cannulae implanted into the lateral ventricles (IV). In the second group, naloxone (0.04, 0.4, and 1.6 micrograms) and morphine (5, 10 and 20 micrograms) were injected through cannulae implanted into the MPC, 1.5 mm above the tip of the stimulating electrodes. In the first group, spontaneous motor activity (SMA) was measured as a control for non-specific effects (sedation or motor dysfunction). In the second group SS, contralateral to the microinjected side, served as control. SS and SMA were were measured 1 and 2 h postinjection. One hour after IV injection of morphine SS was not affected, although SMA was decreased. Two hours postinjection, on the contrary, SS was increased while SMA remained decreased. Similar effects were found with IV microinjections of BW 180. Naloxone, intraperitoneally injected, reversed all these effects. Naloxone or morphine injected intracerebrally (MPC) produced no changes in SS either in the injected or in the contralateral side, which served as control. The present results suggest that the effects found with IV injections of opioids on SS of the MPC are indirect (through activation of other brain areas) and not mediated by a direct action on the neurochemical substrates underlying this behaviour in the MPC.

Animals↗
PubMed1984

Symmetrical distribution of amino acid neurotransmitters in the right and left cerebral cortex of the rat.

The level and activity of seven amino acids were examined in both the right and left areas of the cerebral cortex of the rat in order to determine their respective symmetrical distribution. In the first experiment, alanine, glycine, threonine, serine, GABA, aspartate, and glutamate were measured in six different regions of the cortex: medial, sulcal, and dorsal prefrontal as well as parietal, temporal, and occipital. The differences in the level of these amino acids in symmetrical regions of either side of the cortex were not statistically significant. In the second experiment, the in vivo synthesis from the [14C]glucose precursor of three amino acids, glutamate, glutamine, and GABA was measured using the cortical push-pull perfusion technique in the freely moving rat. Although differences in synthesis were found between the prefrontal and parietal areas of the cortex, no changes occurred between right and left hemispheres. These results indicate that for the resting levels of the amino acids examined in this study, no differential asymmetric distribution exists between right or left cortical regions of the rat's brain.

Alanine↗
PubMed1984

Regional synthesis of 14C-amino acids in cerebral cortex of the unanesthetized rat: simultaneous analysis by "push-pull" perfusion.

Rats were surgically prepared with two sets of guide cannulae positioned bilaterally to rest below the superficial layer of the prefrontal, parietal and occipital regions of the cerebral cortex. Following post-operative recovery, two cortical sites were labeled simultaneously by microinjection of a 1.0 microliter volume of 5.0 microCi of D-[U-14C]-glucose. After a 20 min interval for incorporation into amino acids, two sites were concurrently perfused over an interval of 20 min by means of a push-pull cannula system with an artificial CSF solution at a rate of 25 microliters/min. A thin-layer chromatographic assay for separation of amino acid neurotransmitters was used to estimate the content in each sample of perfusate of labeled gamma-amino-butyric acid (GABA), glutamate, glutamine, aspartate and glycine. The results show that recovery of three amino acids, GABA, aspartate and glycine, was uniform among the three areas of the rat's cortex. However, the synthesis of labeled glutamate and glutamine was significantly lower within the parietal cortex in comparison to that of the prefrontal and occipital regions. Overall, the recovery of GABA was proportionally higher whereas glycine was lower than that of the other amino acids. The difference in the results from previous observations can be attributed to the distribution of amino acids in neurons and their terminals in deeper layers of cortex, which may give a different profile of release when epidural measurements are obtained.

Amino Acids↗
PubMed1983

Effects of agonists and antagonists of D1 and D2 dopamine receptors on self-stimulation of the medial prefrontal cortex in the rat.

The possible participation of D1 versus D2 dopamine receptors in mediating dopaminergic neurotransmission of self-stimulation (SS) in the medial prefrontal cortex (MPC) of the rat was studied neuropharmacologically. Intracerebral as well as intraperitoneal injections of agonists and antagonists of dopamine receptors were used in this study. In all experiments performed with systemic injections, spontaneous motor activity (SM) was measured parallel to self-stimulation behavior as control for non specific effects of the drugs. Intracranial injections were done unilaterally serving SS of the contralateral side (not injected or injected with 0.9% NaCl) as control in the same animals. Spiroperidol and pimozide were used as D1-D2 dopamine antagonists, while sulpiride was used as a specific D2 antagonist. Apomorphine was used as D1-D2 agonist, while bromocriptine and lergotrile were used at doses in which these ergot drugs are considered predominantly D2 agonists. Sulpiride, intraperitoneally or intracerebrally injected at the same locus at which the stimulating electrode was located produced no effect on SS. On the contrary, the D1-D2 antagonists, spiroperidol and pimozide intraperitoneally or intracerebrally injected produced a dose-dependent decrease on SS. On the basis of these data it is suggested, that the dopamine neurotransmission involved in SS of the MPC is mediated via D1 dopamine receptors. This suggestion is further emphasized by the results obtained with the agonists, apomorphine, bromocriptine and lergotrile. Apomorphine produced a dose-related decrease on SS and a decrease at lower doses and an increase at higher doses on SM. Bromocriptine and lergotrile had, on the contrary, no effect on SS and a dose-related decrease on SM.

Animals↗
PubMed1983

Afferent pathways to points of self-stimulation in the medial prefrontal cortex of the rat as revealed by the horseradish peroxidase technique.

Afferent projections to points of self-stimulation (SS) in the medial prefrontal cortex (MPC) of the rat were studied using the horseradish peroxidase (HRP) technique. Intracranial microinjections of HRP (30%) were delivered at the same stereotaxic points at which the electrodes eliciting SS were located. Retrogradely transported HRP labeled neurons in different thalamic, hypothalamic, mesencephalic and pontine areas. In the thalamus, labeled neurons were found in the dorsomedial, anteromedial, anteroventral, ventral, ventromedial, posteromedial, paratenial, parafascicular nuclei and n. reuniens. Labeled neurons in mesencephalic areas were found in the n. interpeduncularis, ventral tegmental area (AVT) and substantia nigra (SN). In the pons, labeled neurons were found in the locus coeruleus and in the periaqueductal gray. Other nuclei in which labeled neurons were also found were: lateral hypothalamus (LH), periventricular gray and zona incerta (ZI). Theoretically it is possible that all these afferent areas contribute to SS of MPC. This assumption is discussed and criticized in connection with previous literature on SS. It is suggested that only specific areas and their projections are good candidates for the neural mechanisms involved in the reward produced by electrical stimulation of the prefrontal cortex.

Afferent Pathways↗