Seasonal variation in plasma prolactin response to D-fenfluramine in healthy subjects

Abnormal neuroendocrine response to clomipramine in hereditary affective psychosis

BACKGROUND

Blunting of prolactin response after serotonergic stimulation during a major depressive episode has been described by several investigators. In this study, the neuroendocrine responses to clomipramine were assessed in remitted patients suffering from hereditary depression.

METHODS

Twenty remitted patients from 11 large families with multigenerational, multiple cases of major affective disorder (bipolar disorder n=15, recurrent depression n=5, according DSM-IV) and 12 healthy relatives were investigated. After intravenous application of 12.5 mg of the serotonin re-uptake inhibitor clomipramine, serum prolactin and cortisol levels were analysed.

RESULTS

Patients and comparison group did not differ significantly with respect to age, baseline prolactin and cortisol concentrations. A gender effect was found in an exploratory analysis for prolactin but not for cortisol and therefore the data for prolactin were analysed separately. After clomipramine infusion, the increase of cortisol was significantly lower in patients than in the comparison group (P=.046). For prolactin, this effect could be found in the male (P=.012) as well as in the female (P=.007) subsample.

CONCLUSIONS

These results suggest that blunted prolactin and cortisol responses to serotonergic stimulation are characteristic for remitted depressive patients with previous episodes of major affective disorders.

Lack of seasonal rhythms in central serotonergic function in boys with ADHD

This study examined seasonal variations in central 5-HT function in a relatively large sample of prepubertal boys with attention-deficit/hyperactivity disorder (ADHD). In addition, seasonal differences in central 5-HT function among aggressive and non-aggressive children in the sample were explored. Ninety-three boys with ADHD were divided into aggressive (n=54) and nonaggressive (n=39) groups based on parental responses to interviews and ratings of behavior. Central 5-HT function was assessed by measuring the prolactin response to a single 1 mg/kg oral dose of d,l-fenfluramine. The prolactin values were derived from different children over the course of eight years, but were collapsed across years and analyzed in terms of day of the year. Cosinor analysis revealed no annual, bi-annual, 3-monthly, 2-monthly, monthly, or bi-monthly rhythms in the prolactin response in the entire sample of boys with ADHD. Moreover, there was no evidence of seasonal differences in the prolactin response between the aggressive and non-aggressive subgroups. These results indicate that seasonality-related variance is not a threat to the validity of the neurochemical procedure and does not account for the inconsistencies in the studies of central 5-HT and aggression in children with ADHD.

Correlation between ultraviolet radiation level and the incidence of late-onset corneal haze after photorefractive keratectomy

PURPOSE

To investigate the correlation between environmental changes in ultraviolet (UV) radiation levels and the incidence of late-onset cornea haze (LOCH) after photorefractive keratectomy (PRK).

SETTING

SynsLaser Clinic, Tromsø, Norway.

METHODS

The study comprised 404 eyes that had myopic PRK and photoastigmatic refractive keratectomy from February 1996 through July 1998. The high latitude (70 degrees N) of the observation site provided "natural laboratory" conditions to look at the occurrence of LOCH with high and low UV-radiation levels, which occurred during summers and winters, respectively. The diagnostic criterion for LOCH was acute haze of grade > or =2 occurring between 4 and 12 months postoperatively.

RESULTS

The follow-up ranged from 12 to 41 months. Of the 314 eyes that met the inclusion criteria, 11 developed LOCH when the environmental UV-radiation level was high. No eye developed LOCH when the level was low. The correlation between a high level of environmental UV radiation and the occurrence of LOCH was statistically significant (P =.001).

CONCLUSION

Environments with high UV-radiation levels may increase the risk of LOCH after PRK in eyes with moderate to high myopia. Use of UV-protective eyewear should be encouraged during the first year after PRK.

Neuroendocrine correlates of depression in abstinent heroin-dependent subjects

The functions of the central alpha-adrenergic, serotoninergic and dopaminergic systems were investigated in 28 heroin-dependent subjects 6-8 weeks after detoxification, and in 22 healthy control subjects (group C). Fourteen heroin-dependent subjects with depressive comorbidity (group A), and 14 heroin-dependent subjects without other Axis I and II pathologies (group B) were included among abstinent substance abusers. Norepinephrine (NE) function was evaluated by growth hormone (GH) responses to acute stimulation with clonidine (clon); serotonin (5-HT) function by prolactin (PRL) and cortisol (CORT) responses to acute stimulation with D-fenfluramine (D-fen) and dopamine (DA) function by GH and PRL responses to acute administration of bromocriptine (brom). Central NE activity, as measured by the GH-clon test, seems to be well preserved both in A and B subjects. PRL and CORT responses to D-fen were significantly blunted both in A subjects and in B subjects, in comparison with control subjects (C); the PRL response in A subjects was significantly lower than in B subjects. The DA system of B subjects was found unimpaired; in contrast, a significantly higher GH response to brom in A subjects (depressed) could express D2 post-synaptic receptor hypersensitivity and, therefore, decreased pre-synaptic DA release. In sum, the study of central monoamine function revealed an alteration only of the 5-HT system in detoxified heroin-dependent subjects without psychiatric comorbidity, which might be a trait character of these subjects, possibly involved in the pathogenesis of the disorder. A more significant impairment of 5-HT function and the hypersensitivity of post-synaptic DA receptors in A subjects suggests that specific biological correlates of psychiatric comorbidity may characterize substance abuser subtypes.

Neuroendocrine correlates of temperamental traits in humans

Studies investigating temperament traits in humans and their biological correlates have found high levels of novelty seeking (NS) linked with dopaminergic system changes, and particularly a deficit of dopamine transporter. Harm avoidance and reward dependence, on the other hand, appeared to be associated, respectively with serotonin and noradrenaline changes. In the present study, we have investigated the dopaminergic (DA), serotonergic (5-HT), and noradrenergic (NE) functions in healthy volunteers by challenging the monoamine systems with the DA agonist bromocriptine, the 5-HT agonist D-fenfluramine, and the NE agonist clonidine, respectively. Parallel to this investigation, we examined the temperament traits of our subjects by measuring NS, harm avoidance (HA) and reward dependence (RD) using the 'Three-dimensional Personality Questionnaire' (TPQ). The aims of the study were to see whether or not the monoamine functions were correlated with temperament traits. Bromocriptine challenge induced a significant GH increase and a significant suppression of PRL. D-fenfluramine test significantly increased PRL and cortisol plasma levels and Clonidine test induced a significant rise in GH values. NS scores showed a significant direct correlation with brom-stimulated GH values (r=0.426, P<0.05) and a significant inverse correlation with brom-inhibited PRL values (r=-0.498, P<0.01). HA scores correlated significantly with D-fen-stimulated PRL and CORT AUCs, (PRL: r=0.424, P<0.05; CORT: r=0. 595, P<0.005). RD scores correlated positively with clon-stimulated GH values (r=0.55; F=8.6; P<0.01) and negatively with brom-inhibited-PRL AUCs (r=-0.439, P<0.05). Our data support Cloninger theory concerning the biological correlates of temperamental traits, and evidence the link between the neuroendocrine responses to dynamic challenges and stable temperament features.

Long-lasting effects of (+/-)3,4-methylenedioxymethamphetamine (ecstasy) on serotonin system function in humans

BACKGROUND

Fifteen (+/-)3,4-Methylenedioxymethamphetamine (MDMA) users, who did not show other drug dependencies or prolonged alcohol abuse, and 15 control subjects were included in the study.

METHODS

Prolactin (PRL) and cortisol (CORT) responses to the serotonergic agonist d-fenfluramine (D-fen), clinical psychobehavioral changes, and psychometric measures were evaluated 3 weeks and then 12 months after MDMA discontinuation.

RESULTS

MDMA users showed significantly reduced PRL and CORT responses in comparison with control subjects at 3 weeks (respectively, p < .001; p < .005). The responses of PRL to D-fen were unmodified at 12 months after prolonged abstinence and were significantly reduced in comparison with controls (p < .001). In contrast, CORT responses in MDMA users were restored after 12 months of abstinence, with significantly higher responses to D-fen, in comparison with 3-week responses (p < .05). MDMA users' high scores on the Novelty Seeking (NS) scale on the Tridimensional Personality Questionnaire (TPQ) appeared unchanged by long-term abstinence. In contrast, Buss Durkee Hostility Inventory (BDHI) (Buss and Durkee 1957) direct and guilt scores decreased significantly after 12 months of abstinence. PRL AUCs at 12 months were inversely correlated with the measures of MDMA exposure (r = -.538).

CONCLUSIONS

Our data indicate long-lasting 5-HT system impairment in abstinent MDMA users although the hypothesis of serotonergic changes attributable to a premorbid condition cannot be excluded. CORT restored responses to D-fen at 12 months, and the correlation of neuroendocrine changes with MDMA exposure suggest that the neuroendocrine impairment may be due to a partially reversible neurotoxic action of MDMA on the human brain.