Inhibitory effect of phentolamine on diazepam-induced growth hormone secretion and lack of effect of diazepam on prolactin secretion in man

Psychotropics and Male Reproduction

Psychotropic drugs, including antidepressants, antipsychotics, and anticonvulsants, all have negative effects on sexual function and semen quality. These adverse events vary among men and are less pronounced for some medications, allowing their effects to be managed to some extent. Use of specific serotonin reuptake inhibitors (SSRIs) is prevalent in men of reproductive age; and application to treat premature ejaculation increases the number of young men on SSRI therapy. Oxidative damage to sperm can result from prolonged residence in the male reproductive tract. The increase in ejaculatory latency seen with SSRIs likely underlies some of their negative effects on semen quality, including higher sperm DNA fragmentation, seen in all SSRIs evaluated thus far. These medications increase prolactin (PRL) levels in some men, and this is often credited with inhibitory effects on male reproduction; however, testosterone levels are generally normal, reducing the likelihood of direct HPG axis inhibition by PRL. The tricyclic antidepressants have also been shown to increase PRL levels in some studies but not in others. The exception is the tricyclic antidepressant clomipramine, which profoundly increases PRL levels and may depress semen quality. Other antidepressants modulating synaptic levels of serotonin, norepinephrine, and/or dopamine may have toxicity similar to SSRIs, but most have not been evaluated. In limited studies, norepinephrine-dopamine reuptake inhibitors (NDRIs) and serotonin agonist/reuptake inhibitors (SARIs) have had minimal effects on PRL levels and on sexual side effects. Antipsychotic medications increase PRL, decrease testosterone, and increase sexual side effects, including ejaculatory dysfunction. The greatest evidence is for chlorpromazine, haloperidol, reserpine, risperidone, and thioridazine, with less effects seen with aripiprazole and clozapine. Remarkably few studies have looked at antipsychotic effects on semen quality, and this is an important knowledge gap in reproductive pharmacology. Lithium increases PRL and LH levels and decreases testosterone although this is informed by few studies. The anticonvulsants, many used for other indications, generally decrease free or bioavailable testosterone with variable effects on the other reproductive hormones. Valproate, carbamazepine, oxcarbazepine, and levetiracetam decrease semen quality; other anticonvulsants have not been investigated for this adverse reaction. Studies are required evaluating endpoints of pregnancy and offspring health for psychotropic medications.

Growth hormone secretion after baclofen administration in different phases of the menstrual cycle in healthy women

AIM

The aim of this study was to investigate the effect of baclofen administration on growth hormone (GH) secretion during different phases of the menstrual cycle.

METHODS

Twelve healthy women (33.6 +/- (SD) 2.8 years; range 23-40 years) with regular menstrual cycles were enrolled. The phases of the menstrual cycle were determined using transvaginal ultrasonography (TV-US) and detecting hormonal serum levels. Plasma GH levels were evaluated during the early follicular, periovulatory and luteal phases of the cycle before and after the baclofen challenge test.

RESULTS

After acute baclofen administration, GH levels increased significantly (p < 0.001) compared to basal values during the periovulatory and luteal phases, while no significant variation was detected during the early follicular phase. In addition, plasma GH levels resulted significantly (p < 0.001) higher during the luteal phase than during the periovulatory phase.

CONCLUSION

Acute baclofen administration induces a significant increase in plasma GH levels in healthy females during the periovulatory and luteal phases, but not during the early follicular phase. These data suggest a modulator role of plasma sex steroids levels on GH release induced by baclofen.

Comparison of effect of ethanol and anticonvulsants on cardiovascular drug-modified cocaine toxicity

The anticonvulsant (AC drug)- or ethanol (EtOH)-modified effects of cardiovascular (CV) drugs against cocaine (COCA)-induced toxicity were examined in male ICR mice. Nontoxic doses of the CV drugs nimodipine (NIMO), prazosin (PRA), phentolamine (PHEN), propranolol (PRO), and enalapril (ENA) were used with or without the AC drugs diazepam (DZP), phenobarbital (PHB), phenytoin (PHY), and EtOH. Each CV drug combined with or without each AC drug was administered intraperitoneally (IP) 5 min before an IP injection of COCA 75 mg/kg. Of the CV drugs examined, PRA 5 mg/kg and PHEN 5 mg/kg protected against COCA-induced seizures, but only the alpha1-adrenergic blocking agent PRA protected against COCA-induced deaths. Of the AC drugs examined, DZP 5 mg/kg and PHB 50 mg/kg, as well as EtOH 3 g/kg, attenuated the severity of the COCA-induced seizures, but only PHB protected against COCA-induced deaths. The total mortality rate was significantly, often synergistically, decreased compared to the COCA-only group when the appropriate CV drugs were combined with the AC drugs: PRA 5 mg/kg in the EtOH-cotreated groups, PRA 5 mg/kg, PHEN 5 mg/kg or ENA 10 mg/kg in the DZP-cotreated groups, and NIMO 5 mg/kg, PRA 5 mg/kg, PHEN 5 mg/kg, or PRO 10 mg/kg in the PHB-cotreated groups. The decrease in the COCA concentration in the blood and/or brain was not always accompanied by an attenuation of the mortality rate. However, the attenuation of severe seizures by a single PRA, PHEN, DZP, or PHB cotreatment was accompanied by a decrease in the brain COCA concentration.

Long-term administration of GHB does not affect muscular mass in alcoholics

Gamma-hydroxybutyric acid (GHB) is a drug recently utilized for alcoholism management. It has been shown that GHB has anabolic effects since it can increase growth hormone (GH) release in healthy subjects. At present, there are no studies investigating body composition in alcoholics during long-term GHB treatment. In this study body composition and GH secretion in alcohol dependent subjects was evaluated during addiction and at different time of GHB administration and alcohol abstinence. A total of 45 male alcohol dependent patients (mean age 39.7+/-9.8 yrs, mean height: 171+/-6.8 cm, body mass index--BMI--22.1+/-1.6 kg/m(-2)) were consecutively enrolled. Body composition was assessed by anthropometry, bioimpedance analysis and tritiated water method. A 7-day food diary was collected. Plasma GH levels were determined by radioimmunoassay. A 6-month total abstinence was obtained in 22 patients, by means of psychological support counseling and self-help groups in 9 subjects and also by 50 mg/kg/day of GHB in 13 subjects. At 1, 2, 3 and 6 months of abstinence, the biochemical assessment and metabolic variables were re-examined. Fat-free mass (FFM) and basal GH secretion were similar at the different times of follow-up in both groups of patients. GHB treated patients and those receiving psychological support alone showed similar values in FFM and GH. Both groups of patients did not differ in FFM and plasma GH level from healthy controls at any of the times evaluated. Waist-to-hip ratio did not differ between patient groups, while higher values were shown in alcoholics with respect to control subjects. The present study shows that long-term administration of GHB did not affect muscular mass and did not determine an increase of GH release in chronic alcoholics. This findings could be due to an impairment of the hypothalamic-limbic system and of GABAergic neurotransmission in alcoholics' brain.

Alcoholism abolishes the gamma-aminobutyric acid (GABA)ergic control of GH secretion in humans

In order to establish possible alterations in the gamma-aminobutyric acid (GABA)ergic control of growth hormone (GH) secretion in alcoholics, 800 mg sodium valproate (a drug enhancing endogenous GABA activity), 10 mg baclofen (a GABA(B) receptor agonist) or a placebo were given orally to nine normal men (age 38-48 years) and nine 2-4-week-abstinent alcoholics (age 35-50 years; duration of alcohol consumption 3-6 years). Blood samples for GH assay were taken every 30 min for the next 150 min. Both drugs induced a significant increment in serum GH levels in the normal controls; mean peak was 7.2 and 3.27 times higher than baseline after sodium valproate and baclofen, respectively. In contrast, GH secretion in alcoholic patients did not change after baclofen or sodium valproate administration. Placebo administration did not modify GH secretion in any subject. In concurrence with previous reports showing alterations of GABAergic neurotransmission in the central nervous system of patients affected by alcoholism, these data show the loss of the GABAergic mechanism(s) underlying the GH response to sodium valproate and/or baclofen action in alcoholism.

Different control mechanisms of growth hormone (GH) secretion between gamma-amino- and gamma-hydroxy-butyric acid: neuroendocrine evidence in Parkinson's disease

The observation that baclofen stimulates growth hormone (GH) secretion in normal men, but not in parkinsonian patients led us to test the GH releasing effect of other gamma-amino-butyric acid (GABA)ergic agents with different mechanisms of action in Parkinson's disease. For this purpose 10 normal men and 10 de novo parkinsonian patients were tested with sodium valproate (800 mg PO), gamma-hydroxybutyric acid (GHB) (25 mg/kg body weight PO) and baclofen (10 mg PO). All drugs induced a significant increment in serum GH levels in the normal controls. On the other hand, GH secretion in parkinsonian patients did not change after baclofen or sodium valproate administration, whereas it showed normal responsiveness to GHB. These data suggest that the mechanism underlying the GH response to GHB is different from that (or those) mediating sodium valproate and/or baclofen action. In addition, the former, but not the latter mechanism appears to be preserved in the parkinsonian brain.

Failure of gammahydroxy butyric acid to stimulate growth hormone secretion in cocaine addicts

This study discusses the effect of gammahydroxy butyric acid (GHB) on growth hormone (GH) secretion changes in cocaine addicts. Ten male cocaine users and 10 normal controls were tested with a single oral administration of GHB at a dose of 25 mg/kg body weight. Cocaine addicts were tested before and after 30 days of abstinence. All subjects underwent a control with a placebo. Basal GH levels were similar in normal controls and cocaine users and remained unmodified during the control test. In the normal control subjects, plasma GH levels rose significantly after the administration of GHB; in contrast, plasma GH concentrations failed to increase after GHB treatment in cocaine addicts. These data show that a chronic abuse of cocaine induces alterations of the GABAergic system which were unmasked by the absent GH response to GHB.

Dose-dependent effects of intravenous alprazolam on neuroendocrine, biochemical, cardiovascular, and behavioral parameters in humans

Neuroendocrine, biochemical, cardiovascular, and behavioral parameters were assessed in seven normal volunteers for 2 h after intravenous administration of alprazolam (APZ). Three doses of APZ (0.003, 0.007, and 0.02 mg/kg) were administered to each subject in a random order with at least 4 days between infusions. Plasma growth hormone and sedation increased in a dose dependent manner after APZ, and there was a dose dependent change in the shape of the cortisol response to APZ. No dose-response relationships were evident for plasma ACTH and norepinephrine. These differences in dose-response relationships may reflect the involvement of multiple systems in controlling neuroendocrine, biochemical, and subjective responses to APZ infusion. The optimal dose of APZ needed to produce a neuroendocrine or behavioral change appears to differ depending on the parameter of interest.

Serum postdexamethasone prolactin measures in depressive patients and control subjects

Recently, some researchers noted significant positive relationships between postdexamethasone serum cortisol and prolactin levels, whilst endogenous depressives exhibited a significantly lower suppression of prolactin by dexamethasone than non-endogenous patients or normal controls. To ascertain the extent of prolactin responses to dexamethasone in severely depressed patients, we measured 8 a.m. pre- and postdexamethasone prolactin levels in 104 depressed and 42 normal subjects. Serum cortisol levels were also determined in depressed patients before and after dexamethasone administration. We found a significant suppressive effect of dexamethasone on prolactin levels. There were no significant differences either in pre- or postdexamethasone prolactin, or in actual dexamethasone-induced decrements in prolactin between normal controls, melancholics, simple major or minor depressed subjects. We have not found any significant relationships between cortisol and prolactin, either under baseline or postdexamethasone conditions.

Reduction of GH response to the GABA-B agonist baclofen in patients with major depression

In order to establish whether alterations in the GABAergic control of GH secretion occur in male patients with major depression, the GH response to the GABAergic-B agonist baclofen (10 mg PO at 0830h) or to placebo was tested in 9 depressed men and in 10 age- and weight-matched male normal controls. The basal concentrations of GH were significantly lower in the depressed patients (0.87 +/- 0.69 ng/ml) than in the normal controls (1.57 +/- 0.33 ng/ml) (p = 0.011) and were not modified by the administration of placebo. The administration of baclofen induced a striking, significant increase in GH concentrations in the normal controls (mean peak at 90 min = 6.4 +/- 1.5 ng/ml). In contrast, a slight, nonsignificant GH increase occurred in the depressed patients after baclofen (mean peak at 90 min = 1.57 +/- 1.45 ng/ml). The GH response was significantly lower in the depressed than in the control subjects (p less than 0.001). These data indicate the presence of reduced GABAergic control of GH secretion in male depressed patients.

Intravenous alprazolam challenge in normal subjects. Biochemical, cardiovascular, and behavioral effects

Alprazolam, a novel benzodiazepine derivative is thought to be effective in the treatment of anxiety, panic, and depressive disorders. There is considerable interest in alprazolam's mechanism of action, particularly whether its profile of actions might resemble that of the alpha 2 adrenoreceptor agonist, clonidine. The present study assessed the biochemical, cardiovascular, and behavioral responses of healthy volunteers to acute intravenous infusions of alprazolam and placebo. Alprazolam reduced ACTH and cortisol while increasing growth hormone. There was a transient reduction in plasma norepinephrine and only modest effects on cardiovascular parameters. Subjects became quite sedated after intravenous alprazolam. This pharmacodynamic profile resembles that previously reported for traditional benzodiazepines, although alprazolam may be a more potent stimulator of growth hormone release. Alprazolam's effects on growth hormone resemble those of clonidine, but unlike clonidine, alprazolam has relatively little effect on plasma catecholamine and cardiovascular parameters. This suggests that alpha 2 mechanisms do not play a primary role in alprazolam's mode of action. Since alprazolam infusion affects three different measures (ACTH/cortisol, growth hormone, and plasma norepinephrine) thought to be dysregulated in depression, challenge with intravenous alprazolam may prove to be a useful "probe" in affective disorders.

Baclofen-induced growth hormone secretion is blunted in chronic schizophrenics: neuroendocrine evidence for a GABA disturbance in schizophrenia

To substantiate a previously reported disturbance of gamma-aminobutyric acid (GABA) in chronic schizophrenia, plasma growth hormone (GH) response to a direct GABA agonist (baclofen, 10 mg) was assessed in 12 unmedicated chronic schizophrenic males and 10 sex- and age-matched healthy controls. Baclofen and placebo were administered orally, in a double-blind design, and blood samples were collected before and 30, 60, 90, 120, 180, and 240 min after drug or placebo administration. Baclofen induced a clear-cut rise in plasma GH levels over baseline values, but the GH increase observed in the patients was significantly smaller than that in controls. These results support the idea that GABA mechanisms may be impaired in chronic schizophrenia.

The natural history of tolerance to the benzodiazepines

Dependence on benzodiazepines following continued use is by now a well-documented clinical phenomenon. Benzodiazepines differ in their dependence potential. The present studies were aimed at examining the possibility that differential rates of tolerance development might account for differences in dependence risk. Four studies are reported. The first three studies concerned normal subjects. The development of tolerance over a fifteen day period was demonstrated for three different benzodiazepines (ketazolam, lorazepam and triazolam) using two paradigms. Tolerance in terms of a reduction in effectiveness of a repeated given dose was most notable for the benzodiazepine with a medium elimination half-life (lorazepam) for physiological, behavioural and subjective measures. In the case of the drug with the longest elimination half-life (ketazolam) reduction in effectiveness could only be assumed to be occurring if account was taken of the steady increase in plasma concentrations of active metabolites. For this drug it seemed that the physiological measures were those most likely to demonstrate the development of tolerance. Although triazolam showed few significant drug effects on this paradigm (testing being 12 hours after ingestion of this short half-life benzodiazepine), tolerance was seen to develop on some subjective measures. Using an alternative method of testing tolerance, assessing responses to a diazepam challenge dose, a high degree of tolerance on two-thirds of the measures was observed in subjects when pretreated with the benzodiazepine with the most marked accumulation of active metabolites (ketazolam). The other two drugs also led to tolerance development on a range of measures; this was more marked for lorazepam than triazolam. Blunting of the growth hormone response to diazepam was the most sensitive and reliable method of detecting tolerance to the benzodiazepines. Symptoms on discontinuation of the two weeks' intake of the benzodiazepines were marked for all the drugs but unrelated to either the tolerance induced or the elimination half-life of the particular drug. A further clinical study revealed that tolerance persisted in a group of long-term benzodiazepine users for between four months and two years following complete abstinence from the drug. These patients appeared to be less affected by diazepam in terms of its commonly observed subjective effects, regardless of their original medication. These ex-long-term users of benzodiazepines were, however, more likely to manifest two specific types of effects--immediate 'symptom' reduction and exacerbation of 'withdrawal symptoms' over the subsequent week.(ABSTRACT TRUNCATED AT 400 WORDS)

Growth hormone response to sodium valproate in chronic schizophrenia

The hypothesis of a gamma-aminobutyric acid (GABA) involvement in the pathophysiology of schizophrenia has been recently proposed but not confirmed. As GABA has been shown to affect basal growth hormone (GH) secretion in humans, the assessment of plasma GH response to a GABAergic drug, such as sodium valproate (SV), in schizophrenic subjects might be a tool with which to investigate central GABA activity in this illness. For this purpose, we administered orally 800 mg of SV or placebo to 13 chronic schizophrenics and to 10 normal controls, and measured plasma GH levels before and after the drug administration. SV enhanced basal GH secretion in healthy male volunteers, but not in chronic schizophrenics. These results suggest a defect of the endogenous GABA system in chronic schizophrenia. Whether the reduced responsiveness observed represents a primary defect or a secondary alteration of the GABA system in schizophrenia is as yet unknown.

Basal and post-dexamethasone cortisol and prolactin concentrations in depressed and non-depressed patients with chronic pain syndromes

To assess the behavior of two putative neuroendocrine markers of depression in chronic pain, the authors determined plasma cortisol and prolactin concentrations before and after dexamethasone in 52 hospitalized male chronic pain patients. Their psychiatric diagnoses by Research Diagnostic Criteria (RDC) were: major depression (N = 24; 44.2%), minor depression (N = 10; 19.2%), another RDC diagnosis (N = 7; 13.5%) and not mentally ill (N = 12; 21.6%). Failure to suppress cortisol after dexamethasone (a positive DST) occurred in 43.5% of those with major depression, 20% of those with minor depression, 42.8% of those with other psychiatric diagnoses and in 8.3% of patients without a psychiatric disorder. The frequency of non-suppression was significantly different only for patients with major depression compared to those without diagnosable psychiatric disorder. Mean basal cortisol concentrations at 08.00, 16.00 and 23.00 h did not differ among psychiatric diagnostic groups of pain patients, or between these groups and healthy volunteers. Levels of prolactin, but not cortisol, were significantly correlated with the severity of mood disturbances. These findings suggest strategies using multiple endocrine markers to distinguish pain from depression should be explored.

Lack of effect of im diazepam administration on hGH and hPRL secretion in normal and acromegalic subjects

The usefulness of diazepam as a provocative stimulus for hGH secretion has been suggested as a simple, reliable test in clinical hGH assessment of pituitary disorders. We have investigated the effects of diazepam (10 mg im) on plasma hGH and hPRL in 5 normal and 7 acromegalic subjects. No significant variations in hGH and hPRL levels have been observed in any of the studied subjects. These findings indicate that the drug is ineffective on hGH and hPRL release and that it cannot be considered a valid provocative test either in normal or acromegalic subjects.

Evidence for a GABAergic control of the exercise-induced rise in GH in man

The effect of the GABAergic drug sodium valproate (SV) on the exercise-induced release of growth hormone (GH) was investigated in 10 healthy males. The exercise test consisted of using a stationary bicycle ergometer at 450 kg/min for 20 min. SV 600 mg blunted the increase in GH induced by the exercise, suggesting GABAergic regulation of GH secretion in man, at least under certain physiological conditions.

Changes in dopamine receptor sensitivity in humans after heavy alcohol intake

Dopamine (DA) sensitivity, assessed through maximal growth hormone (GH) response to stimulation by apomorphine (APO) (0.18-0.24 mg iv) was studied in 16 chronic alcoholics newly admitted after a period of heavy alcohol intake. Repeated hormonal tests were thereafter performed during a 2-month period under strictly controlled conditions to avoid relapse into alcohol consumption. Eight healthy volunteers with alcohol consumption slightly less than that of the general population were used as controls. It was found that DA sensitivity in the early abstinence phase was higher than later in the 2-month recovery period but not significantly different from control values. The relatively higher DA sensitivity in the early abstinence phase might be responsible for a lower threshold for psychotic symptoms and neuroleptic-induced extrapyramidal side effects. The results of this study give further evidence of a prolonged recovery phase after heavy alcohol intake.

Comparison of growth hormone stimulation induced by desimipramine, diazepam and metaclazepam in man

A comparison of the effect on growth hormone (GH) stimulation in men (n = 6) of desimipramine (DMI), a tricyclic antidepressant, and of the benzodiazepine derivatives diazepam and metaclazepam with that of a placebo, showed that only DMI caused a significant (p less than 0.01) GH stimulation. After DMI, all six subjects showed a GH stimulation greater than 7.5 ng/ml, whereas after diazepam or metaclazepam, only three of the six subjects showed GH stimulation greater than 7.5 ng/ml, and the other three showed only a very small change, or no change at all in GH secretion. Higher GH stimulation occurred after diazepam (10 mg i.v.) than after diazepam (10 mg p.o.). No dose-dependent difference in GH stimulation after metaclazepam (10 and 30 mg p.o.) was apparent. No side effects appeared after administration of DMI during the test period (180 min); however, after administration of the benzodiazepine derivatives, sedative effects were clearly noted. DMI thus causes reliable GH stimulation in healthy male subjects, whereas GH stimulation could only be measured in some of the subjects after diazepam and metaclazepam.