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Biomedical subjects

R M Post

Publications and source records attributed to R M Post.

At least 361 records · Page 20Linked to original sources
PubMed1982

Impaired behavioral sensitization to cocaine in vasopressin deficient rats.

Behavioral sensitization to cocaine involves progressive and long-lasting increases in hyperactivity and stereotypy in response to the same daily dose. In order to test whether vasopressin, a neuro-hormone implicated in drug tolerance and in other models of learning and memory, affected behavioral sensitization, cocaine was administered daily to animals with hereditary absence of vasopressin. Brattleboro homozygotes which lack vasopressin show deficient onset and persistence of cocaine-induced behavioral sensitization compared to heterozygote, litter-mate controls. These data extend previous reports of vasopressin's role in memory and long-term coding of behavior to the model of pharmacologically-induced behavioral sensitization.

Animals↗
PubMed1982

Peptides in the cerebrospinal fluid of neuropsychiatric patients: an approach to central nervous system peptide function.

This review highlights that essentially all of the recently discovered putative central nervous system (CNS) peptides and other peptide substances are measurable in human cerebrospinal fluid (CSF). Preliminary evidence also suggests that peptides in CSF may have an active regulatory role in relation to CNS function and behavior. Even if this is not the case, CSF peptides may prove to be a useful indirect marker of CNS peptide function and metabolism. Alterations in peptides have been reported in neurological and psychiatric illness, pain symptoms and their treatment, symptoms such as anxiety, and following treatment with CNS active drugs such as carbamazepine. CSF methodologies provide a strategy for the study of the interaction of classical neurotransmitters and peptide substances and their relationship to neural function and behavior in man. Assessment of peptides in CSF may supplement post mortem studies of peptide levels and receptor distribution and help lead to new diagnostic and treatment approaches in neuropsychiatric disorders.

Adrenocorticotropic Hormone↗
PubMed1982

Human platelet vasopressin receptors.

Specific saturable binding of 125I-arginine-vasopressin to human platelets is described. For ten normal volunteers the mean (+/- S.D.) KD is 5.6 nM (+/- 2.1) and the mean (+/- S.D.) Bmax is 115 fmoles/mg protein (+/- 30). Association studies indicate that equilibrium is reached after 90 minutes on ice. Pharmacological inhibition studies with analogues indicate that the platelet receptor is very similar to the kidney medulla receptor. The function of the receptor may involve serotonin release and platelet aggregation. Vasopressin binding to platelets should provide a readily means of assessing vasopressin receptor function in man.

Arginine Vasopressin↗
PubMed1982

Central nervous system gamma-aminobutyric acid activity in man. Relationship to age and sex as reflected in CSF.

Central nervous system gamma-aminobutyric acid (GABA) activity was demonstrated to be an age- and sex-dependent phenomenon through the study of GABA concentration in lumbar CSF obtained from 87 drug-free normal individuals. Evaluation of the data from homogeneous subgroups of this population disclosed that both the propensity of lumbar CSF GABA levels to decrease with age and the magnitude of the rostrocaudal GABA concentration gradient are more pronounced in females, suggesting possible neuroendocrine involvement. Thus, age and sex are important variables that normally influence central GABAergic activity. Patient populations included in clinical investigations must be age- and sex-matched to avoid invalid conclusions biased by these physiologic variations in CSF GABA concentrations.

Adult↗
PubMed1982

Growth hormone response to clonidine as a probe of noradrenergic receptor responsiveness in affective disorder patients and controls.

The growth hormone (GH) response to the alpha-adrenergic agonist clinidine was blunted in 19 depressed patients compared to 20 controls. The difference remained significant when age- and sex-matches pairs of patients and controls were compared from this sample, either including or excluding subjects with elevated GH baseline levels. Plasma levels of free 3-methoxy-4-hydroxyphenyl-glycol (MHPG) were assayed in blood samples drawn just before the clonidine infusion. A modest negative correlation was found between the plasma MHPG values and the magnitude of the GH responses to clonidine, although baseline plasma MHPG levels were not significantly different between patients and controls. The diminished GH response to clonidine observed suggests that many depressed patients may have decreased alpha-adrenoreceptor responsiveness. Decreased responsiveness may in some cases be associated with relatively increased indices of presynaptic noradrenergic availability. Such a model might have implications for understanding the functional status of the noradrenergic neurotransmitter system in depressed patients and the possible subtyping of affective disorder patients.

Clonidine↗
PubMed1982

Platelet 3H-imipramine binding in euthymic bipolar patients.

Several recent studies have reported decreased maximal binding (beta max) of 3H-imipramine to platelets obtained from depressed patients. 3H-Imipramine binding was measured in 12 medication-free euthymic bipolar patients and 12 normal volunteers to determine whether the decreased beta max persisted in the euthymic state. No differences between these two groups were found in beta max or binding affinity (Kd). This suggests that 3H-imipramine binding to platelets is not a state-independent marker for affective illness.

Adult↗
PubMed1982

Platelet GABA-transaminase in affective illness.

Platelet gamma-aminobutyric acid (GABA)-transaminase was measured in 18 bipolar patients, 59 normal volunteers, and 9 pairs of monozygotic twins. A significantly lower mean activity was observed in the bipolar group, although lower female bipolar values may account for most of the difference. Enzyme activity was correlated in monozygotic twins, suggesting genetic influences on enzyme activity. Values obtained in the postprandial state were significantly lower than values in the fasting state. These data are discussed in light of other evidence of altered GABA metabolism in affective illness.

4-Aminobutyrate Transaminase↗
PubMed1982

Kindling and carbamazepine in affective illness.

Kindling represents a process in which increasing behavioral and convulsive responses occur to repetition of the same stimulus over time. Increased behavioral response can also occur to repetition of the same dose of psychomotor stimulant or dopamine agonist, i.e., behavioral sensitization. These two models, which may have important implications for the progressive development of psychopathology in a variety of neuropsychiatric syndromes, are reviewed. Carbamazepine, a drug of choice in treatment of temporal lobe and limbic seizures and effective in inhibiting kindling, has been used as a treatment of primary and secondary affective illness. The efficacy of carbamazepine in affective illness and its clinical and theoretical implications are discussed.

Affective Disorders, Psychotic↗
PubMed1982

Endorphins in the cerebrospinal fluid of psychiatric patients.

In this paper we have reported the results of studies in psychiatric patient groups using the strategy of measuring opioid activity and beta-endorphin (ir) in CSF. Our findings do not lend support to the notion of excess endorphin activity in schizophrenia, but rather suggest the possibility of a decrease in endogenous opioid activity in some schizophrenic patients. In affectively ill patients our data suggest that there may be a relative change in endogenous opioid system activity across state change in manic-depressive illness. Who also found a relationship between nurses' ratings of anxiety and CSF opioid activity in depressed patients, although it is unknown whether this directly relates to the pathophysiology of this symptom, or is related to stress response. The relationship between CSF opioid activity and HPA axis activity, as reflected by urinary free cortisol excretion, supports the notion of important physiologic relationships between these systems and raises the issue of a role for the endogenous opioid system in the abnormal activation of this system in depression. Finally, the finding of increased CSF opioid activity in anorexia nervosa patients when a minimum weight coupled with data relating endogenous opioids to eating behavior raises interesting questions regarding a possible involvement of the endogenous opioid system involvement in this illness.

Adult↗
PubMed1982

Effect of lidocaine pretreatment on cocaine-induced behavior in normal and amygdala-lesioned rats.

Animals treated with daily lidocaine (60 mg/kg, i.p.) develop progressive increases in pathological eating of nonnutritive substances, i.e. omniphagia. Bilateral amygdala lesions blocked the development of lidocaine-induced omniphagia. Following 32 daily injections of lidocaine, both lesioned and nonlesioned animals showed greater cocaine-induced hyperactivity than saline-pretreated controls. These data suggest cross-sensitization between the two local anesthetics lidocaine and cocaine, even though lidocaine does not possess the psychomotor stimulant effects of cocaine. Amygdala-lesioned animals showed greater cocaine-induced vertical rearing activity compared to controls. The lesion data suggest that the amygdala is differentially involved in the progressive behavioral sensitization to both chronic lidocaine and cocaine.

Amygdala↗
PubMed1982

Potentiation of antidepressant effects by L-triiodothyronine in tricyclic nonresponders.

Six women and 6 men who were treated in double-blind fashion major depressive illness did not respond to imipramine or amitriptyline, 150-300 mg/day, during periods of 26-112 days. After the addition of 25 micrograms/day (10 patients) or 50 micrograms/day (2 patients) of L-triiodothyronine (T3), 9 patients showed statistically significant improvement in depression scores; in 8 patients the response was marked. Improvement generally began within 1-3 days and was noted in all aspects of the depressive syndrome; side effects were minimal. T3 did not change plasma levels of imipramine or desipramine or their ratio but did suppress serum thyroxine.

Adolescent↗
PubMed1982

The "atypical" clinical picture of adolescent mania.

The authors examined the records of 9 manic patients under age 21 and 12 over age 30 for the incidence of "schizophrenic" and manic symptoms. The adolescent patients had a higher incidence of each of the 10 schizophreniform symptoms rated and significantly more delusions and ideas of reference. Significantly more adolescent patients had 3 or more schizophreniform symptoms; they also had symptoms typical of mania. These findings highlight the diagnostic importance of affective symptoms in psychotic adolescents with mixed symptoms and raise important clinical and theoretical questions about the atypical clinical picture of manic-depressive illness in young patients.

Adolescent↗
PubMed1982

Plasma and CSF GABA in affective illness.

CSF and plasma GABA was measured in patients with bipolar affective illness and matched controls. There was no correlation between CSF and plasma GABA in 10 pairs of simultaneously obtained samples. Plasma GABA was significantly lower in a group of 10 euthymic medication-free bipolar patients compared to 41 normal volunteers (P less than .02). This finding was replicated in a second study involving 6 patients and 10 normal volunteers. Twin studies showed a high correlation between members of 11 monozygotic twin pairs (P less than .008). Diurnal variation was minimal, but bimonthly sampling over one year revealed somewhat higher values in the late summer compared to late winter.

Adult↗