Density Of 3H-imipramine Binding Sites Research Articles

Effect of prenatal exposure to tianeptine on different neurotransmitter receptors and 5-HT-stimulated inositol phosphate formation in rat brain.

Tianeptine, an antidepressant drug enhancing 5-HT uptake, was given to pregnant rats in the last 15 days of gestation and different neurotransmitter receptors as well as 5-HT2 receptor-linked inositol phosphate formation were measured in the brains of the offspring. Prenatal exposure to tianeptine significantly decreased the density of 3H-imipramine binding sites in the cerebral cortex of the pups without affecting beta-adrenoceptors, serotonin 5-HT2 and 5-HT1B receptors or inositol phosphate formation after a 5-HT challenge. Striatal dopamine D2 receptors labelled with 3H-spiroperidol were not changed but an apparent increase in the affinity of dopamine was noticed in the pups prenatally exposed to the drug. The results show that the neurochemical profile of tianeptine markedly differs from that of most antidepressants.

Effect of phototherapy on 3H-imipramine binding sites in patients with SAD, non-SAD and in healthy controls

The effect of incandescent light treatment on the density of 3H-imipramine binding sites ( B max) was investigated in 17 patients with seasonal affective disorder, in eight patients with non-seasonal depression and in six healthy volunteers. A significant increase in mean B max value parallel to a marked improvement of the depressive symptoms was found only in patients with SAD. No effect was observed either on mean B max value or on clinical symptoms in patients with non-SAD and on mean B max value in healthy volunteers.

Relationship between seasonal patterns of platelet serotonin uptake and 3H-imipramine binding in depressed patients and normal controls

Chicz-DeMet, Aleksandra, Christopher Reist, and Edward M. DeMet: Relationship Between Seasonal Patterns of Platelet Serotonin Uptake and 3H-Imipramine Binding in Depressed Patients and Normal Controls. Prog. Neuro-Psychopharmacol. & Biol. Psychiat. 1991, 15 (1): 25–39. 1. 1. Significant seasonal variations were found in the velocity of serotonin (Vmax) uptake and the density of 3H-imipramine binding sites (Bmax) in blood platelets from normal controls. 2. 2. Peak 3H-imipramine ( 3H-IMI) binding was found in February whereas peak serotonin (5HT) uptake was found in June and these measures were not correlated in paired comparisons. 3. 3. Both Vmax and Bmax values of depressed patients deviated from the normal seasonal pattern with lower uptake and binding in the patient group. 4. 4. A comparison of Vmax and Bmax deviations from the normal patterns of uptake and binding revealed a significant correlation between these measures such that patients with low Vmax values were the same as those with low Bmax values. 5. 5. The results support previous claims that the 3H-IMI binding site may be closely associated with, or identical to, a 5HT transport carrier. 6. 6. A significant correlation between uptake and binding further suggests that a common defect may be responsible for observed decreases in Vmax and Bmax values of depressed patients.

Platelet Tritiated Imipramine Binding and Serotonin Uptake in Depressed Patients and Controls

We measured platelet tritiated imipramine binding and serotonin uptake in 51 depressed patients and 43 normal controls. Although there were no significant differences in platelet 3H-imipramine binding or serotonin uptake when the total group of depressed patients was compared with controls, depressed women (n = 32) had a significantly lower maximal density of 3H-imipramine binding sites (beta max) than control women (n = 25). Moreover, among the total group of depressed patients, there were significant negative correlations between the beta max values and plasma cortisol levels at 4 PM (n = 41) and 11 PM (n = 41) following dexamethasone administration. These negative correlations between beta max and cortisol levels were strongest among melancholic patients both at 4 PM before dexamethasone administration (n = 14) and at 11 PM after dexamethasone administration (n = 15). These data suggest that the reported decrease in beta max found among depressed patients may be related to and is perhaps secondary to the hypercortisolemia of depression.

Seasonal variation of platelet serotonin uptake and 3H-imipramine binding in normal and depressed subjects

Density of 3H-imipramine binding sites and serotonin (5-HT) uptake in blood platelets were repeatedly recorded in normal controls ( n = 9) and depressed patients ( n = 7 for the imipramine binding assay and n = 4 for the serotonin uptake) over a 1-year period. The study demonstrated a striking seasonal variation of both parameters in both groups, with lower values in winter and spring than in summer and fall. No difference in the density of 3H-imipramine binding sites was found between the two populations throughout the year, but serotonin uptake was significantly decreased in depressed patients in May and September. These results underscore the importance of studying controls and patients at the same time of the year.

Imipramine treatment differentially affects platelet 3H-imipramine binding and serotonin uptake in depressed patients

Uptake of serotonin and 3H-imipramine binding in platelets of depressed patients were investigated simultaneously with changes in clinical state. Both V max for serotonin uptake and B max for 3H-imipramine binding were significantly lower in unmedicated depressed patients with respect to normal subjects. Successful treatment with impiramine led to a significant increase in B max for 3H-imipramine binding, without significant change in V max for serotonin uptake. B max values increased to the normal range following complete, rather than partial clinical improvement. These data indicate that successful antidepressant treatment may increase the density of 3H-imipramine binding sites on platelets by a process which is independent of the uptake of serotonin.

Platelet 3H-imipramine binding: A state-dependent marker in depression

1. Reduced density of 3H-imipramine binding sites (B max) to platelets has been reported in depressed patients during an episode of illness. In the present study we assessed the usefullness of decreased B max of platelet 3H-imipramine binding as an indicator of the depressed state. We also investigated the effect of long-term treatment with imipramine on platelet 3H-imipramine binding. 2. A comparison of platelet 3H-imipramine binding in 10 drug-free depressed patients and 8 normal volunteers revealed significantly lower mean Bmax values in depressed patients, whereas the affinity (K d) of 3H-imipramine binding was identical in both groups. 3. A longitudinal study of platelet 3H-imipramine binding in 10 depressed patients during and after imipramine treatment (125–200 mg/day) revealed consistently low B max values despite clinically meaningful improvement. However, B max values increased significantly following complete remission and remained elevated even after imipramine had been discontinued for 4 weeks. 4. These findings suggest that decrease in the sensity of platelet 3H-imipramine binding sites in depressed patients is not likely to be a direct drug effect and that normalization of this variable may follow clinical remission.

High-affinity 3H-imipramine binding: a new biological marker in depression.

High-affinity binding of the tricyclic antidepressant drug, 3H-imipramine, has been demonstrated in the brain of various species including man. These specific binding sites have many of the characteristics to be expected for the specific site of action of a drug and appear to be associated with the neuronal uptake mechanism for serotonin. Chronic administration of tricyclic antidepressant drugs or the prolonged application of other antidepressant therapies, such as electroshock and sleep-deprivation, resulted in decreases in the density of 3H-imipramine binding sites. Apparently identical 3H-imipramine binding sites have been found in blood platelets from a variety of species including man. Clinical studies have shown that untreated severely depressed patients have a lower density of binding sites in their platelets than control volunteers. Longitudinal studies of these patients indicate that the density of 3H-imipramine binding sites tends not to change during treatment with tricyclic antidepressant drugs and the subsequent recovery from depression. 3H-imipramine binding in brain and platelets is proposed as a new biological marker in depression and as a useful research tool in biochemical and clinical pharmacological studies in affective disorders.

High-affinity binding of 3H-imipramine in brain and platelets and its relevance to the biochemistry of affective disorders

Specific high-affinity binding of 3H-imipramine has been demonstrated in the brain of various species including man. These binding sites have many of the characteristics to be expected for a pharmacological receptor and appear to be associated with the neuronal uptake mechanism for serotonin. Different antidepressant treatments like chronic administration of tricyclic antidepressants, chronic electroshock or sleep-deprivation result in decreases in the density of 3H-imipramine binding sites in normal animals. 3H-imipramine binding sites have also been found in blood platelets from different species including man. These sites are identical to those described in the brain. Clinical studies have shown that untreated severely depressed patients have a lower density of 3H-imipramine binding sites in their platelets when compared with control volunteers of the same age and sex. Longitudinal studies indicate that the low density of 3H-imipramine binding sites does not change during treatment with tricyclic antidepressant drugs and the subsequent clinical recovery from depression. 3H-imipramine binding in brain and platelets is proposed as a useful research tool in biochemical and clinical studies in affective disorders.