Endocrinology. 1993 Jul;133(1):312-20.
Chronic treatment of rats with the antidepressant amitriptyline attenuates the activity of the hypothalamic-pituitary-adrenocortical system.

Reul JM, Stec I, Soder M, Holsboer F.

Max Planck Institute of Psychiatry, Department of Neuroendocrinology, Munich, Germany.

The effects of the tricyclic antidepressant amitriptyline on the rat hypothalamic-pituitary-adrenocortical (HPA) system were studied. The time-course experiments showed that amitriptyline, given via the drinking water (4.5 mg/kg.day), produces significant decreases (P < 0.05) in adrenal weight after 5 (-20%) and 7 weeks (-21%) of treatment. Hippocampal mineralocorticoid receptor (MR) levels were down-regulated at days 3 (-27%) and 7 (-20%), and transiently up-regulated at 2 (+40%), 5 (+74%), and 7 (+18%) weeks of treatment. Hippocampal glucocorticoid receptor (GR) levels were slightly down-regulated at days 3 (-8%) and 7 (-17%), transiently up-regulated by 26% at 5 weeks, and indistinguishable from controls after 7 weeks of treatment. MR levels were unchanged in the hypothalamus and neocortex, whereas hypothalamic GR concentrations were elevated and neocortical receptor levels were not altered. Dose-response experiments showed significant decreases in adrenal weight when rats were treated with 4.5 (-14%), 8.8 (-16%) and 14.5 (-13%) mg/kg.day antidepressant, but this applied only for the 4.5- (-14%) and 8.8- (-12%) mg/kg.day doses when the ratio of adrenal weight to body weight was considered. The dose-response relationship regarding hippocampal GR content displayed an inverted U-shaped curve, whereas this was less marked for MR levels. A dose of 4.5 mg/kg.day appeared to be optimal for the rise in MR as well as GR. Concerning the neuroendocrine implications of chronic antidepressant treatment, amitriptyline (5 weeks, 4.5 mg/kg.day) produced significant decreases in basal (ACTH, -47%; corticosterone, -31%) as well as stress (30 min novel environment)-induced plasma ACTH (-38%) and corticosterone (-57%) levels. Previous experiments have forwarded a role of limbic MR in the tonic control of basal HPA activity. Based on the present data, we hypothesize that during amitriptyline treatment a rise in limbic MR may be the initial phenomenon in a successively adjusting HPA system, as evidenced by the decreasing plasma hormone concentrations, declining adrenal size, and up-regulation of GR in particular brain regions.

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J Neurochem. 1993 Feb;60(2):595-601.
Ca2+ release from inositol 1,4,5-trisphosphate-sensitive Ca2+ store by antidepressant drugs in cultured neurons of rat frontal cortex.

Shimizu M, Nishida A, Hayakawa H, Yamawaki S.

Department of Psychiatry and Neuroscience, Kure National Hospital, Hiroshima, Japan.

The ability of antidepressant drugs (ADs) to increase the concentration of intracellular Ca2+ ([Ca2+]i) was examined in primary cultured neurons from rat frontal cortices using the Ca(2+)-sensitive fluorescent indicator fura-2. Amitriptyline, imipramine, desipramine, and mianserin elicited transient increases in [Ca2+]i in a concentration-dependent manner (100 microM to 1 mM). These four AD-induced [Ca2+]i increases were not altered by the absence of external Ca2+ or by the presence of La3+ (30 microM), suggesting that these ADs provoked intracellular Ca2+ mobilization rather than Ca2+ influx. All four ADs increased inositol 1,4,5-trisphosphate (IP3) contents by 20-60% in the cultured cells. The potency of the IP3 production by these ADs closely correlated with the AD-induced [Ca2+]i responses. Pretreatment with neomycin, an inhibitor of IP3 generation, significantly inhibited amitriptyline- and imipramine-induced [Ca2+]i increases. In addition, by initially perfusing with bradykinin (10 microM) or acetylcholine (10 microM), which can stimulate the IP3 generation and mobilize the intracellular Ca2+, the amitriptyline responses were decreased by 76% and 69%, respectively. The amitriptyline-induced [Ca2+]i increases were unaffected by treatment with pertussis toxin. We conclude that high concentrations of amitriptyline and three other ADs mobilize Ca2+ from IP3-sensitive Ca2+ stores and that the responses are pertussis toxin-insensitive. However, it seems unlikely that the effects requiring high concentrations of ADs are related to the therapeutic action.

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Pharmacology. 1993;46(1):23-32.
Absence of relationship between antiarrhythmic effects of antidepressant drugs and lipid peroxidation.

Bril A, Abadie C, Ben Baouali A, Maupoil V, Rochette L.

Laboratoire de Physiopathologie et Pharmacologie Cardiovasculaire Experimentales, Facultes de Medecine et de Pharmacie, Dijon, France.

Tricyclic antidepressant drugs may affect the cardiovascular system, principally in patients with preexisting cardiac disease. The present study was undertaken to compare the effects of amitriptyline and mianserin with those of tianeptine, an atypical tricyclic antidepressant drug, in rat isolated working heart subjected to a local myocardial ischemia. Coronary, aortic and cardiac flows, and heart rate remained stable during the whole preischemic period in control hearts. Ligation of the left main coronary artery induced a 50% decrease in coronary, aortic and cardiac flow without any change in heart rate. Reperfusion was characterized by the occurrence of ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) and by a marked reduction in cardiodynamic parameters. Amitriptyline (1 and 10 mumol/l) and mianserin (1 and 10 mumol/l) exhibited an antiarrhythmic activity against reperfusion arrhythmias. Tianeptine (1 and 10 mumol/l) was not able to reduce the incidence of reperfusion arrhythmias. Although tianeptine did not change heart rate, mianserin and amitriptyline induced a bradycardia. Mianserin and amitriptyline improved the cardiac recovery of cardiac function during reperfusion. The cardiodynamic parameters (coronary, aortic and cardiac flows) were not altered by tianeptine during the preischemic period. Furthermore, these parameters were similar to those observed in the control group both during ischemia and reperfusion. The beneficial effects of amitriptyline and mianserin observed in the setting of myocardial reperfusion were not associated with a reduced lipoperoxidation investigated by using an in vitro model in the presence or absence of a free-radical-generating system. The results of the present study indicate that the pronounced antiarrhythmic activities of mianserin and amitriptyline cannot be explained by an antiperoxidative action of these drugs.

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Eur J Clin Pharmacol. 1993;44(1):97-9.
Minor and clinically non-significant interaction between toloxatone and amitriptyline.

Vandel S, Bertschy G, Perault MC, Sandoz M, Bouquet S, Chakroun R, Guibert S, Vandel B.

Laboratoire de Pharmacologie Clinique, CHU de Besancon, France.

The possibility of a pharmacokinetic interaction between amitriptyline and toloxatone (a new MAOI-A) has been studied in 17 depressed in-patients. Amitriptyline and its demethylated and hydroxylated metabolites in blood and urine were measured at steady state after the administration of amitriptyline with and without toloxatone in steady state. The metabolic status of patients was determined using the dextromethorphan phenotyping test. There was only a minor pharmacokinetic interaction between amitriptyline (AMT) and toloxatone, with a small increase in the AMT/NT (nortriptyline) plasma ratio: 0.68 before and 0.78 after toloxatone. The urinary excretion and plasma levels of AMT and its metabolites were not affected by the co-therapy. Three of the patients were poor metabolisers, but this did not predict the magnitude of the drug interaction. The interaction does not justify plasma level monitoring of amitriptyline as the change in pharmacokinetics was so small.

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J Reprod Med. 1993 Jan;38(1):9-13.
Dysesthetic ("essential") vulvodynia. Treatment with amitriptyline.

McKay M.

Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia 30322.

Twenty patients with chronic vulvar burning (vulvodynia) who had relief of symptoms only after treatment with low-dose amitriptyline were studied retrospectively. These patients had several factors in common, which suggested a possible neurologic component to their symptoms. The dosage of amitriptyline (initiated at 10 mg, gradually increased to 40-60 mg daily) was not sufficient to treat depression, but was in the range effective for other cutaneous dysesthesias. This study defines dysesthetic ("essential") vulvodynia, and describes a typical profile and symptom pattern for patients most likely to respond to treatment with amitriptyline (an average age of 66 with vulvodynia for three years). Dysesthetic vulvodynia appears to be a subset different from vulvar vestibulitis and other types of vulvodynia that are less responsive to treatment with tricyclic antidepressants.

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J Forensic Sci. 1993 Mar;38(2):316-22.
Preliminary observations of the effects of amitriptyline in decomposing tissues on the development of Parasarcophaga ruficornis (Diptera: Sarcophagidae) and implications of this effect to estimation of postmortem interval.

Goff ML, Brown WA, Omori AI, LaPointe DA.

Department of Entomology, University of Hawaii, Manoa, Honolulu.

Larvae of Parasarcophaga ruficornis (Fabricius) (Diptera: Sarcophagidae) were reared on tissues from rabbits administered different dosages of amitriptyline to study the effects of this drug on the development of this insect species. The rabbits were given 300, 600, and 1000 mg of amitriptyline via ear vein infusion. No significant differences in rates of larval growth were observed among the colonies. Durations of the larval stage were significantly longer for larvae fed on tissues from rabbits receiving amitriptyline. Larval mortality was observed to be 5.5% for the control colony, but ranged from 40.5 to 57.5% for the test colonies. Durations of the puparial stage were significantly longer for the colonies fed on tissues from the rabbits receiving the 600 and 1000 mg dosages of amitriptyline than for the control and colony fed on tissues from the rabbit receiving the 300 mg dosage. Observed differences in the durations of the larval and pupal stages from the test colonies were sufficient to alter a postmortem interval estimate by up to 77 h, if based on normal developmental patterns for this species at 26 degrees C. Presence of amitriptyline and nortriptyline could be detected in larvae from all colonies fed on tissues from the rabbits receiving amitriptyline using high-performance liquid chromatography (HPLC).

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Pharmacol Biochem Behav. 1993 May;45(1):65-70.
Effects of bulbectomy and subsequent antidepressant treatment on brain 5-HT2 and 5-HT1A receptors in mice.

Gurevich EV, Aleksandrova IA, Otmakhova NA, Katkov YA, Nesterova IV, Bobkova NV.

Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow region.

The effects of bilateral olfactory bulbectomy on serotonergic 5-HT2 and 5-HT1A receptor binding were studied in the frontal cortex (FC), limbic structures (LS), including the hippocampus, amygdala, olfactory tubercule, and piriform cortex, and hypothalamus (HTH) in mice. Bulbectomy resulted in the increase of Bmax for [3H]spiperone binding with 5-HT2 receptors in FC in C57Bl/6j. The receptors in LS and HTH remained unchanged. Subchronic treatment of the bulbectomized mice with antidepressant trazodone (20 mg/kg/day, IP, 14 days) induced downregulation of 5-HT2 receptors in FC and LS. The other two antidepressants used, amitriptyline (20 mg/kg/day, IP, 14 days) and imipramine (10 mg/kg/day, IP, 14 days), did not alter these receptors. [3H]8-OH-DPAT binding with 5-HT1A receptors was not altered by bulbectomy in any brain area in C57Bl/6j mice. Amitriptyline and trazodone decreased Bmax for these receptors in FC in the bulbectomized mice while imipramine was ineffective. Amitriptyline and imipramine significantly increased Bmax and decreased Kd in HTH, and trazodone displayed the same tendency. Bulbectomy did not alter 5-HT2 receptors in DBA/2j mice. Amitriptyline increased Kd in the all brain areas without changing Bmax in the bulbectomized DBA/2j mice. Trazodone significantly decreased Bmax in FC and increased Kd in FC and LS. Imipramine decreased Bmax while increasing Kd in LS. The possible involvement of the serotonin receptor subtypes in the bulbectomy-induced behavioral deficits and in the restorative action of the antidepressants is discussed.

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