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Biomedical subjects

M S Kafka

Publications and source records attributed to M S Kafka.

At least 37 records · Page 2Linked to original sources
PubMed1982

Effects of chronic lithium, clorgyline, imipramine, fluphenazine and constant darkness on the alpha-melanotropin content and circadian rhythm in rat brain.

The effects of constant darkness, chronic lithium, clorgyline, imipramine and fluphenazine treatment on the content and diurnal rhythm of alpha-MSH in rat forebrain were investigated. The persistence of the alpha-MSH rhythm in constant darkness demonstrated that the rhythm was circadian in nature. Constant darkness increased the 24 h mean alpha-MSH concentration in brain while lithium, fluphenazine and imipramine decreased it. In addition, imipramine and clorgyline delayed the phase of the alpha-MSH circadian rhythm while lithium advanced it.

Animals↗
PubMed1982

Clorgyline delays the phase-position of circadian neurotransmitter receptor rhythms.

The number of alpha- and beta-adrenergic, muscarinic cholinergic, opiate, and benzodiazepine receptors in rat forebrain, and dopamine and benzodiazepine receptors in striatum, change throughout the day. The diurnal rhythms of these receptors were altered by treatment with the monoamine-oxidase inhibitor clorgyline: following treatment some or all rhythm characteristics of wave form, amplitude, 24-h mean, and phase, were affected. One common effect of treatment was a delay in phase-position of binding to alpha- and beta-adrenergic, opiate and benzodiazepine receptors. Additionally, the nocturnal elevation in pineal melatonin which normally returns to baseline at light onset, persisted 3 h into the light period after clorgyline administration. These biochemical observations extend behavioural findings that clorgyline can delay the phase-position of rodent nocturnal activity onset, and does so by slowing the central circadian pacemaker.

Animals↗
PubMed1982

Effect of lithium on circadian neurotransmitter receptor rhythms.

Chronic lithium administration significantly changes characteristics of the circadian rhythms in rat brain alpha- and beta-adrenergic, muscarinic acetylcholine, dopamine, opiate, and benzodiazepine receptors. There are changes in the timing of the peak number of receptors (phase-position), in the amplitude of the rhythms, and in the 24-hour mean number of receptors. The circadian rhythm in the number of forebrain alpha- and beta-adrenergic and benzodiazepine receptors is abolished. The phase-position of forebrain acetylcholine and opiate receptors and striatal benzodiazepine receptors is delayed. As the rhythms of the dopamine receptor number and alpha-melanocyte-stimulating hormone secretion become bimodal, their phase positions are difficult to evaluate. The mean number of forebrain alpha- and beta-adrenergic, acetylcholine, opiate, and striatal benzodiazepine receptors increases. The mean number of forebrain benzodiazepine and striatal dopamine receptors and the mean concentration of alpha-melanocyte-stimulating hormone decreases. Lithium has profound effects on each of the receptor rhythms measured. Slowing and altering circadian rhythms may contribute to the therapeutic effects of chronic lithium treatment in affective disorders.

Animals↗
PubMed1981

Circadian and seasonal rhythms in alpha- and beta-adrenergic receptors in the rat brain.

Circadian rhythms in the numbers of alpha- and beta-adrenergic receptors exists in the rat forebrain and hypothalamus. These rhythms are endogenous as they persist in the absence of time cues. The alpha- and beta-receptor rhythms differ both in their shapes (wave form) and in the timing (phase) of the peak numbers. In the course of the year, there are shifts in the timing of both alpha- and beta-receptor peaks. Circadian rhythms in synchronizing both the synaptic events and the behaviors related to them to the photoperiod of the natural environment.

Animals↗
PubMed1981

Circadian rhythm in rat brain opiate receptor.

To investigate diurnal variations in opiate receptor binding, the amount of specifically bound [3H]naloxone was measured at 4-h intervals across a 24-h period in the forebrains of rats that had been housed under a controlled light--dark cycle (lights on from 07.00 to 19.00 h) for 3 weeks. A significant rhythm with a peak at 22.00 h was found, the amplitude was 46--78%. In the absence of time cues, this circadian rhythm persisted with a peak at 02.00--06.00 h and an amplitude of 88%. Scatchard analysis indicated that the differences in binding throughout the day were due not to changes in affinity, but to changes in the number of binding sites.

Animals↗
PubMed1981

Sleep deprivation: effects on circadian rhythms of rat brain neurotransmitter receptors.

Specific binding of ligand to rat forebrain alpha- and beta-adrenergic, muscarinic cholinergic, opiate, benzodiazepine, and striatal dopamine receptors was measured at 4-hour intervals during the last 13 hours of a 24-hour sleep deprivation period, and during the first 11 hours of the recovery sleep period. In non-sleep-deprived controls a 24-hour rhythm in binding was evident. The minor differences between the sleep deprivation group and the control group consisted mainly in a reduced amplitude of the 24-hour rhythm under the sleep deprivation schedule. The results indicate that neither the 24-hour forced locomotion nor the subsequent prominent sleep rebound is accompanied by marked changes in the number of neurotransmitter receptors and their circadian rhythms.

Animals↗
PubMed1981

Seasonal variations in the endogenous rhythm of dopamine receptor binding in rat striatum.

In four experiments, performed at different months throughout the year, a significant daily rhythm in dopamine receptor binding has been observed. This rhythm is endogenous, as it persists in the absence of time cues. Striking differences in wave form, amplitudes, and timing of peaks during the year suggest that the endogenous rhythm undergoes seasonal variations.

Animals↗
PubMed1980

Dopamine receptor binding in rat striatum: ultradian rhythm and its modification by chronic imipramine.

To investigate diurnal variations in dopamine receptor binding, the amount of specifically bound 3H-spiroperidol was measured at 4-h intervals over a 24-h period in the striatum of rats which had been housed under a controlled 12-h light-dark cycle (lights on 7 a.m.). A highly significant ultradian rhythm with peaks at 2 a.m. and 2 p.m. was found with an amplitude of about 75%. Chronic imipramine modified the rhythm such that the two peaks occurred 4 h later and amplitude as well as 24-h mean of binding decreased. Scatchard analysis at times of least and greatest binding indicated that the differences in binding were due not to changes in the affinity, but in the number of binding sites. These results are interpreted with regard to the mode of action of psychoactive drugs and to postulated changes of receptor sensitivity in neurological and psychiatric disorders.

Animals↗
PubMed1980

Indomethacin increases leucocyte beta-adrenoreceptors in man.

1. The effect of indomethacin, an inhibitor of prostaglandin synthesis, on number and sensitivity of alpha- and beta-adrenoreceptors was studied in normal healthy volunteer subjects. 2. The subjects were studied under metabolic conditions. To achieve inhibition of prostaglandin synthesis indomethacin (2 mg day-1 kg-1) was given orally for 7 days. This dose decreased urinary excretion of prostaglandin E-like immunoreactivity by 70%. 3. The number or alpha-adrenoreceptors was measured by the specific binding of [3H]dihydroergocryptine to platelet membranes and that of beta-adrenoreceptors by the binding of [3H]dihydroalprenolol to leucocyte membranes. 4. The number of alpha-adrenoreceptors did not change with indomethacin, nor did basal, prostaglandin E1- or noradrenaline-stimulated cyclic AMP production by platelet membranes. In contrast, the number of beta-adrenoreceptors increased by 92%. Indomethacin did not affect, however, basal, 1-isoprenaline- or prostaglandin E1-stimulated cyclic AMP production in leucocyte membranes. 5. These results suggest that a reflex-mediated decrease in sympathetic discharge in response to an indomethacin-induced decrease in release of vasodilator prostaglandins may lead to an 'up-regulation' of beta-adrenoreceptor sites.

Adult↗
PubMed1979

Reduced cyclic AMP production in the blood platelets from schizophrenic patients.

The authors assessed alpha-adrenergic receptor function in blood platelets from chronic schizophrenic patients and normal control subjects. The number of receptors was measured by the specific binding of the alpha-adrenergic antagonist [3H]dihydroergocryptine to the platelets. A physiological response of the platelets to agonist occupancy of the alpha-adrenergic receptors was measured by the norepinephrine inhibition of prostaglandin E1(PGE1)-stimulated cyclic AMP (cAMP) production. cAMP production in male schizophrenic patients was lower than in normal male subjects. alpha-Adrenergic receptor function was similar in patients and normal control subjects of both sexes. Normal male subjects had about 1.5 times the number of alpha-adrenergic receptors as normal females and generated about 1.8 times the quantity of PGE1-stimulated cAMP.

Adolescent↗
PubMed1979

Effect of inhibition of prostaglandin synthesis on sympathetic nervous system function in man.

The effect of inhibition of prostaglandin synthesis by indomethacin on the function of the peripheral sympathetic nervous system was studied in eight normotensive subjects. Sympathetic nervous function was assessed by measurement of plasma norepinephrine, alpha-adrenergic receptor sites on platelet membranes, and urinary excretion of epinephrine and norepinephrine. Treatment with indomethacin for 7 days resulted in significant decreases in basal plasma norepinephrine from 134 +/- 7 to 99 +/- 6 (SEM) pg/ml (P less than 0.01), a 26% decrease. Posturally stimulated norepinephrine concentrations (337 +/- 14 pg/ml in control studies) were 255 +/- 18 pg/ml (P less than 0.02), 25% lower, with indomethacin. Plasma norepinephrine after 5-min compression of hand grip (468 +/- 47 pg/ml in control) was 331 +/- 30 pg/ml (P less than 0.005), 29% lower, with indomethacin. The number of platelet alpha-adrenergic receptor sites did not change with indomethacin, nor did prostaglandin E1-stimulated cAMP production by platelet membranes. In addition, indomethacin produced no change in urinary excretion of norepinephrine or epinephrine. It is suggested that inhibition of prostaglandin synthesis may lead, via baroreceptor feedback, to a decrease in plasma norepinephrine concentration.

Adult↗