Morning variations of plasma homovanillic acid in untreated schizophrenic patients

Plasma variations in stress markers: clinical trial of two anesthetics used in regional block in the extraction of impacted inferior third molars

OBJECTIVES

Was to evaluate the effect of different regional anesthetics (articaine with epinephrine versus prilocaine with felypressin) on stress in the extraction of impacted lower third molars in healthy subjects.

STUDY DESIGN

[corrected] A prospective single-blind, split-mouth cross-over randomized study was designed, with a control group. The experimental group consisted of 24 otherwise healthy male volunteers, with two impacted lower third molars which were surgically extracted after inferior alveolar nerve block (regional anesthesia), with a fortnight's interval: the right using 4% articaine with 1:100.000 epinephrine, and the left 3% prilocaine with 1:1.850.000 felypressin. Patients were randomized for the first surgical procedure. To analyze the variation in four stress markers, homovanillic acid, 3-methoxy-4-hydroxyphenylglycol, prolactin and cortisol, 10-mL blood samples were obtained at t = 0, 5, 60, and 120 minutes. The control group consisted of 12 healthy volunteers, who did not undergo either extractions or anesthetic procedures but from whom blood samples were collected and analyzed in the same way.

RESULTS

Plasma cortisol increased in the experimental group (multiple range test, P<0.05), the levels being significantly higher in the group receiving 3% prilocaine with 1:1.850,000 felypressin (signed rank test, p<0.0007). There was a significant reduction in homovanillic acid over time in both groups (multiple range test, P<0.05). No significant differences were observed in homovanillic acid, 3-methoxy-4-hydroxyphenylglycol or prolactin concentrations between the experimental and control groups.

CONCLUSIONS

The effect of regional anesthesia on stress is lower when 4% articaine with 1:100,000 epinephrine is used in this surgical procedure.

Inter- and intra-individual variability in the levels of plasma homovanillic acid in schizophrenic patients

BACKGROUND

Changes in the levels of homovanillic acid in blood plasma (pHVA) may reflect changes which occur in the brain. In healthy individuals, this concentration of pHVA is stable over time.

METHODS

Over the course of one month, we studied 98 acute schizophrenic patients who had not been taking any medication but were administered neuroleptics upon hospital admission, together with 23 chronic schizophrenic patients on long-term treatment from whom medication was withdrawn. Blood samples were taken at regular intervals from each individual and the concentration of plasma homovanillic acid was measured.

RESULTS

We found relative stable values of pHVA with an intraclass correlation coefficient of 0.363 in acute patients and 0.638 (p<0.0001) in chronic patients, although no differences were found in mean values (13.79 and 14.18 microg/L, respectively) or in the variation range (7.20 to 26.7 microg/L and 6.96 to 29.96 microg/L respectively). The index of individuality was calculated to be 1.36 in acute patients and 0.74 in chronic patients.

CONCLUSIONS

Despite the wide range of values in the concentration of pHVA and the presence of pharmacological stimuli, we found a certain reproducibility in the levels of this dopamine metabolite. These findings are consistent with the idea that the dopaminergic activity is characterized by a constitutive value which would be under genetic control. The higher stability observed in chronic patients may reflect a weaker, age-related dopaminergic plasticity; conversely, it may indicate that a lack of plasticity in response to a pharmacological stimulus may be an indicator of poorer prognosis.

Sex differences in plasma homovanillic acid levels in schizophrenia and normal controls: relation to neuroleptic resistance

Plasma homovanillic acid (pHVA) levels were compared in a large number of neuroleptic-resistant and -responsive schizophrenic patients (male/female = 161/46) and normal controls (67/27), and correlated with various measures of psychopathology. Psychopathology was evaluated with the brief psychiatric rating scale, the Schedule for Affective Disorders and Schizophrenia-Change version (SADS-C) and SADS-C Global Assessment Scale, the Scale for Assessment of Negative Symptoms, the Scale for Assessment of Positive Symptoms (SAPS), and the Quality of Life Scale. No significant differences in pHVA levels between neuroleptic-resistant (n = 104) or -responsive (n = 103) schizophrenic patients, and normal controls, were found; however, there was a main effect for sex, due to higher pHVA levels in women than men. There were no diagnosis x gender or age effects on pHVA levels. No significant correlations were observed between psychopathology ratings and baseline pHVA levels, except with the Hallucinations subscale of SAPS in neuroleptic-responsive patients. Neither duration of neuroleptic washout nor plasma prolactin levels correlated with pHVA levels. Further studies on the origin and significance of the gender difference in pHVA are indicated.