Cocaine use disorder effects on blood oxytocin levels and OXTR DNA methylation

Substance use disorders have been associated with alterations in the oxytocinergic system, but few studies have investigated both the peptide and epigenetic mechanisms potentially implicated in the regulation of oxytocin receptor. In this study, we compared plasma oxytocin and blood DNA methylation in the OXTR gene between people with and without cocaine use disorder (CUD). We measured the oxytocin levels of 51 people with CUD during acute abstinence and of 30 healthy controls using an enzyme immunoassay. The levels of DNA methylation in four CpG sites at exon III of the OXTR gene were evaluated in a subsample using pyrosequencing. The Addiction Severity Index was used to assess clinical characteristics. We found higher oxytocin levels in men with CUD (56.5 pg/mL; 95% CI: 48.2-64.7) than in control men (33.6 pg/mL; 95% CI: 20.7-46.5), while no differences between women with and without CUD were detected. With a moderate effect size, the interaction effect between group and sex remained significant when controlling for height, weight and age data. A positive correlation in the CUD sample was found between oxytocin levels and days of psychological suffering prior to treatment enrollment. No group differences were observed regarding DNA methylation data. This suggests that CUD is associated with higher peripheral oxytocin levels in men during acute abstinence. This finding may be considered in future studies that aim at using exogenous oxytocin as a potential treatment for cocaine addiction.

Oxytocin Receptor Exon III Methylation in the Umbilical Cord Blood of Newborns With Prenatal Exposure to Crack Cocaine

BACKGROUND

Prenatal cocaine exposure (PCE) is associated with behavioral, cognitive, and social consequences in children that might persist into later development. However, there are still few data concerning epigenetic mechanisms associated with the effects of gestational cocaine exposure, particularly in human newborns.

AIMS

We investigated the effects of PCE on DNA methylation patterns of the Oxytocin Receptor (OXTR) gene in the umbilical cord blood (UCB). The relationship between UCB DNA methylation levels and the severity of the mother's cocaine use during pregnancy was also evaluated.

METHODS

In this cross-sectional study, 28 UCB samples of newborns with a history of crack cocaine exposure in utero and 30 UCB samples of non-exposed newborns (NEC) were compared for DNA methylation levels at two genomic loci located in exon III of the OXTR gene (OXTR1 and OXTR2) through pyrosequencing. Maternal psychopathology was investigated using the Mini International Neuropsychiatric Interview, and substance use characteristics and addiction severity were assessed using the Smoking and Substance Involvement Screening Test (ASSIST).

RESULTS

No differences between newborns with a history of PCE and NEC were observed in OXTR1 or OXTR2 DNA methylation levels. However, regression analyses showed that maternal addiction severity for crack cocaine use predicted OXTR1 DNA methylation in newborns.

CONCLUSION

These data suggest that OXTR methylation levels in the UCB of children are affected by the severity of maternal crack cocaine usage. Larger studies are likely to detect specific changes in DNA methylation relevant to the consequences of PCE.

Lymphogranuloma venereum serovar L2b in Portugal

Summary

Chlamydia trachomatis, serovar L2, is the causative agent of lymphogranuloma venereum (LGV), which during recent years has been responsible for various outbreaks reported among men who have sex with men (MSM) in Western Europe, America, Canada and Australia. Samples from nine patients with chronic proctitis, seen at a local hospital were sent to us for identification of C. trachomatis serovar L2. The presence of C. trachomatis serovar L DNA was identified by realtime polymerase chain reaction (PCR) in two patients. They both had high positive C. trachomatis antibody titres (≥ 10,000) and were found to be infected with serovar L2b by sequencing after amplification of the omp 1 gene by a nested PCR technique. These two individuals met the diagnostic criteria for LGV serovar L2b infection and, to our knowledge, these are the first cases described in Portugal.

Anorectal lymphogranuloma venereum: the first two confirmed cases in Portugal

We describe two cases of lymphogranuloma venereum (LGV) in men who have sex with men in Portugal in 2008. These first two confirmed cases of LGV L2b proctitis in Portugal highlight the need for an enhanced surveillance programme in Portugal.

Drug induced weight gain, an impediment to successful pharmacotherapy: focus on antipsychotics

The antipsychotic drugs (APDs) are fundamental tools in current psychiatric practice. A new generation of agents, the atypical APDs, represents an important progress in the treatment of psychotic disorders. Unfortunately, some of them induce excessive body weight gain (BWG), obesity, hyperglycemia and dyslipidemia in the following order: clozapine approximately equal to olanzapine > quetiapine > risperidone > ziprasidone = aripiprazole. Appetite stimulation is probably the main mechanism of BWG and this is strongly correlated with the APD affinity for H1 (histaminergic) and alpha1 (adrenergic) receptors. A composed ratio of the APD affinity for diverse neurotransmitters involved in food intake (FI) regulation correlates with BWG as well. Endocrine/metabolic mechanisms, such as the activation of the hypothalamus-pituitary-adrenal axis, changes in insulin sensitivity (by conventional and atypical agents), hyperprolactinemia and gonadal dysfunction (by conventional APDs and risperidone) may also be involved. Importantly, patients with schizophrenia may have a genetically-based predisposition to appetite dysregulation, insulin resistance and endocrine imbalance involving gonadal steroids. Excessive BWG must be prevented or attenuated by proper drug selection, combining or switching agents, nutritional assistance and physical exercise. Amantadine. metformin and reboxetine proved to significantly lessen APD-induced BWG. Notwithstanding this, novel strategies are necessary to treat this side effect in a clinical population particularly prone to poor compliance and under a high risk of negative drug interaction.

[Advances in the molecular treatment of depression]

AIMS

The objective of this study is to survey present and future antidepressant drug therapy based on the progress made in the field of biotechnology.

DEVELOPMENT

The simplistic and mistaken view that one single system of neurotransmission is altered in depression and that there is, therefore, just one single treatment has changed. Molecular biology and Genetics have enabled us to determine other possible chemical alterations in the brain, beyond the sole participation of the monoaminergic modulation systems, which is the classical hypothesis. In this paper we describe the evidence for the relations between depression and the therapeutic effect the classical antidepressants have on: 1. The peptidergic system of the corticotropin-releasing hormone, cortisol and the functional state of its receptors; 2. Intracellular signalling systems such as cAMP on transcription factors like CREB and neurotrophins; 3. The immune system and cytosines; 4. Glutamate transmission; and 5. The neuropeptidergic system of substance P, neuroactive steroids and the neuroglia. This has allowed other biochemical hypotheses about depression and the possibility of new treatments to be put forward.

CONCLUSIONS

We are still not certain about the exact cause or the processes that determine mental illnesses such as depression or how improvements are achieved with the antidepressants we currently have available. Nevertheless, biotechnology is expected to be a great help in advancing towards a better understanding of the interrelations between the nervous, immune and endocrine systems, with their intracellular cascades and final outcomes in genetic expression and protein function, in depression. This will enable more efficient, more selective and faster-acting drugs to be developed and, in the future and with the help of psychogenomics, even make it possible to produce tailor-made medication for each patient.

Obesity and related metabolic abnormalities during antipsychotic drug administration: mechanisms, management and research perspectives

Excessive body weight gain (BWG) is a common side effect of some typical and atypical antipsychotic drugs (APs). Convergent evidence suggests a hierarchy in the magnitude of BWG that may be induced by diverse agents, being very high for clozapine and olanzapine; high for quetiapine, zotepin, chlorpromazine, and thioridazine; moderate for risperidone and sertindole; and low for ziprazidone, amisulpiride, haloperidol, fluphenazine, pimozide, and molindone. BWG may be related to increased appetite that is due to drug interaction with the brain monoaminergic and cholinergic systems and to the metabolic/endocrine effects of hyperprolactinemia. Subjects with schizophrenia and bipolar disorders manifested a significantly high prevalence of diabetes, even before the introduction of atypical APs. However, clozapine and olanzapine appear to display a high propensity to induce glucose dysregulation and dyslipidemia. Sudden BWG, insulin resistance, increased appetite, and related endocrine changes also may be involved in the development of glucose intolerance and dyslipidemia in predisposed individuals. Patients should be informed of these side effects in order to prevent excessive BWG, and their blood glucose and lipids should be monitored before treatment and then at regular intervals. Nutritional advice must be given and regular physical exercise recommended. An appropriate selection of APs ought to be based on drug efficacy for specific patients and assessment of relevant risk factors such as propensity to gain weight; family or personal history of diabetes or hyperlipidemia; and elevated fasting serum glucose, lipid, or insulin levels. At present, there is no standardized pharmacological treatment for AP-induced BWG. Some studies have assessed the effects of agents such as amantadine, orlistat, metformin, nizatidine, and topiramate on AP-induced BWG. Further studies will provide tools to identify patients at high risk for obesity and metabolic abnormalities during AP administration. Excessive body weight gain (BWG), glucose intolerance, and dyslipidemia during treatment with antipsychotic drugs (APs) were reported in the late 1950s [14,101]. However, after 1990, interest in these problems increased noticeably, mainly because of the high propensity of some new atypical APs to induce these side effects (Fig.1). The APs are currently used in diverse mental disorders. Hence, excessive BWG and metabolic dysfunction are not exclusive of subjects with schizophrenia. In the case of bipolar disorders, AP-induced BWG may be additive to that induced by mood stabilizers [14,48,101]. The clinical features [2,14,24,133,139,140] and mechanisms [14,34,68,87,93,101,130] of BWG and metabolic dysfunction have been previously reviewed. In this article, we focus on a unified theory to explain these side effects, based on the interaction of APs with brain neurotransmitters involved in appetite regulation. This review comprises the following sections: 1) the clinical features of AP-induced BWG; 2) the effects of APs on carbohydrate and lipid metabolism in humans and experimental animals; 3) mechanisms involved in BWG, glucose, and lipid dysregulation; 4) strategies for prevention and treatment of these side effects; and 5) research perspectives in the field. The following sources were consulted: MEDLINE, Cochrane database system, and PsychINFO. Numerous articles referred to in leading articles also were consulted. The literature on this subject has increased so rapidly that it was impossible to include all the data recently published. For the first two sections, references that illustrate current controversies in the field were selected.

Endocrine and metabolic abnormalities involved in obesity associated with typical antipsychotic drug administration

In this study, the authors assessed the endocrine system and glucose tolerance in obese and non-obese women chronically treated with typical antipsychotic drugs (AP). In particular, we tested the hypotheses that these subjects display hypogonadism and increased insulin resistance compared to healthy weight-matched controls, as these abnormalities create a tendency towards excessive body weight gain. Twenty-six AP-treated women were matched with 26 healthy women by age, body mass index and day of the menstrual cycle. The following serum variables were evaluated in each subject: glucose tolerance after an oral glucose overload, insulin, leptin, beta-endorphin, reproductive hormones, adrenal steroids and lipids. Compared to controls, AP-treated women displayed significantly higher levels of basal glucose, insulin after 60 min of the glucose overload, prolactin, thyroid stimulating hormone and beta-endorphin, with lower levels of C-Peptide, progesterone, 17-OH progesterone, androstenedione and high-density lipoprotein cholesterol. The levels of estradiol, estrone and leptin did not differ between the groups. Thus, women treated with typical AP appeared to display more insulin resistance than healthy controls, predisposing them to excessive weight gain. Insulin sensitivity might be further impaired when the subject switches to atypical AP administration. Metformin and related agents may reduce body weight in these subjects. The high levels of the opiate beta-endorphin suggest that opiate antagonists such as naloxone and naltrexone might be useful as well. Even though the luteal phase of the menstrual cycle appears to be severely disturbed, the normal serum levels of estradiol and estrone do not support the proposal derived from animal experimental studies about the use of estrogens or tamoxifen to counteract AP-induced obesity.

Antipsychotic drugs and obesity: is prolactin involved?

OBJECTIVES

To correlate the anthropometric indexes (Body Mass Index [BMI] and Waist-Hip ratio [WHR]) with the serum prolactin levels in a heterogeneous population of patients treated with typical antipsychotic (AP) drugs.

METHODS

We evaluated BMI, WHR, and fasting serum prolactin of inpatients (n = 105) and outpatients (n = 122) treated with APs, in outpatients receiving other psychotropic drugs (OPDs) (n = 77), and in drug-free subjects (n = 33). Outpatients had free access to food, whereas the inpatient sample comprised people with a monotonous diet of approximately 2000 Kcal daily.

RESULTS

Prolactin correlated positively with the BMI in the whole group of AP-treated outpatient men (P = 0.03) and with the WHR in AP-treated inpatient men (P = 0.053). Regarding treatment duration, prolactin and BMI correlated positively in men consecutively treated for more than 1 year (P = 0.023). By contrast, a trend toward a negative correlation between prolactin and BMI was observed in AP-treated outpatient women (P = 0.08). No significant correlation, or even a trend, was observed in the other groups.

CONCLUSIONS

Prolactin may be involved in AP-induced weight gain, particularly in men. Future studies should characterize the period of maximal prolactin impact on body weight during AP treatment. Specific populations particularly sensitive to hyperprolactinemia might be identified as well. The negative correlation between prolactin and BMI detected in AP-treated women resembles the dampened prolactin response observed in severe primary obesity.

Body weight gain after administration of antipsychotic drugs: correlation with leptin, insulin and reproductive hormones

Excessive body weight gain, hyperprolactinemia and low gonadal steroid serum levels are often observed during chronic administration of antipsychotic drugs (AP). Clinical and experimental findings suggest that leptin, the peptidic hormone involved in long-term body weight regulation, and reproductive hormones are interrelated. Therefore, we assessed circulating leptin levels in healthy, lean women (n = 12) and men (n = 7) before and after short-term administration of the AP sulpiride (SUL, 200 mg/day). In addition, we studied psychotic obese (n = 9) and lean women (n = 13) under chronic treatment with diverse AP. No significant weight changes were observed after SUL administration in healthy women--initial weight: 54.9+/-2.6 Kg; final weight: 55.04+/-2.6, NS. Leptin levels did not change either: 11.9+/-1.5 ng/ml. vs. 10.6+/-1.3, NS. By contrast, a small, but significant weight gain was found in SUL-treated men--60.6+/-1.9 Kg. vs. 61.3+/-2.1, p = 0.004. Leptin and insulin levels were significantly higher after SUL administration--leptin: 2.77+/-0.22 ng/ml. vs. 13.9+/-2.5, p=0.035; insulin: 3.59+/-0.17 mIU/ml vs. 8.81+/-0.81, p = 0.0001. In these subjects, leptin levels positively correlated with body weight change (p = 0.006), and serum prolactin change (p = 0.001). Obese psychotic women (Body Mass Index, BMI, Kg/m2 = 31.5+/-1.03) displayed higher leptin levels than non-obese psychotic women (BMI = 25.5+/-0.52): 26.8+/-4.8, vs. 12.8+/-3.4 ng/ml, p = 0.006. In these women, a significant positive correlation was found between leptin levels and BMI (p = 0.0001), and between leptin and basal insulin levels (p = 0.001). These results show that the expected circulating leptin elevation which is observed when body weight raises, is preserved in people treated with AP drugs.

Naltrexone does not prevent the weight gain and hyperphagia induced by the antipsychotic drug sulpiride in rats

Few pharmacological tools are currently available to counteract the excessive body weight gain often observed during prolonged administration of antipsychotic drugs. Most antipsychotic drugs block dopamine receptors, and both the brain dopaminergic and opioid systems appear to be involved in initiation and maintenance of feeding behavior, respectively. We evaluated whether the opioid antagonist naltrexone (NAL, 0.5-16 mg/kg/ip for 21 days) (a) affects body weight and food intake in gonadally-intact and drug-free female rats, (b) prevents obesity, hyperphagia, hyperprolactinemia and vaginal cycle disruption induced by long-term administration of the antipsychotic drug sulpiride (SUL, 20 mg/kg/ip for 21 days), or (c) reverses the acute hyperphagia induced by SUL (15 microg bilaterally), when directly applied in the perifornical lateral hypothalamus (PFLH). In drug-free rats, only NAL doses above 4 mg/kg, significantly decreased weight gain and food intake. Even though NAL (1 and 8 mg/kg) significantly attenuated SUL-induced hyperphagia and hyperprolactinemia, it did not reverse at any dose the weight gain and permanent diestrous induced by SUL. In addition, local NAL did not prevent the hyperphagia and polidypsia observed after acute intrahypothalamic SUL. Unexpectedly, the cumulative and 24 h food intake in SUL-treated rats was significantly increased by NAL. Collectively, these results do not support a role for endogenous opiates in the neural and endocrine mechanisms involved in weight gain during prolonged antipsychotic drug administration in rats.

Endocrine effects of lithium carbonate in healthy premenopausal women: relationship with body weight regulation

The mechanisms involved in Li-induced weight gain remain unclear. The higher frequency of obesity in women than in men under Li treatment, suggests a role for reproductive hormones. The serum levels of the following hormones were evaluated in healthy young women at diverse stages of a control menstrual cycle, and during Li carbonate (900 mg/day) or placebo administration: prolactin, luteinizing hormone, follicle-stimulating hormone, 17-1 estradiol, progesterone, thyroxine, thyrotropin, cortisol, dehidroepiandrosterone sulfate, free testosterone, leptin and an oral glucose tolerance test, in order to measure the areas under the glucose and insulin curve. The body weight was assessed the day before and the last day of treatment. The Li serum levels 15 hours after the last dose were 0.31 +/- 0.1 mEq/L. No significant changes in body weight and in the normal fluctuations of the reproductive hormones along the menstrual cycle were observed during Li administration. An increase in the serum levels of thyrotropic hormone ( p = 0.0001) was the only significant effect of Li, which may predispose to excessive weight gain after prolonged administration of the cation. The remarkable lack of effects of Li on these hormones, question the pertinence of studies conducted in healthy volunteers for the comprehension of the obesity observed in psychiatric patients who may be particularly prone to gain weight under prolonged treatment with high dose of Li.

Antipsychotic drug-induced obesity in rats: correlation between leptin, insulin and body weight during sulpiride treatment

Sulpiride (SUL, 20 mg kg-1 day-1) induces weight gain, hyperphagia, hyperprolactinemia, hypogonadism, and perhaps increased insulin sensitivity in rats. Leptin seems to signal the brain about the size of body fat stores and nutrient metabolism. We evaluated the basal serum leptin levels in rats after acute (1 h) or prolonged SUL or vehicle administration (10, 20 and 30 days). At days 10 and 30 leptin was also assessed during a glucose overload test. As the maximal weight gain during SUL administration is observed at days 10-15 of treatment, leptin was measured in a comparison group of insulin-treated rats (5 IU day-1 for 10 days). SUL-treated rats significantly gained weight. However, leptin levels were not significantly increased at any time-point of treatment. SUL did not affect insulin levels either. By contrast, leptin levels were significantly elevated after insulin administration, along with weight gain and hyperinsulinemia. An opposite correlation was also observed at day 10: leptin and insulin correlated negatively in the SUL group and positively in the insulin group. In addition, leptin and the magnitude of weight gain tended to correlate positively after SUL treatment, but negatively after insulin administration. SUL-treated rats, thus, appear to exhibit an unusual type of weight gain, characterized by normal circulating leptin and insulin levels. Such a particular leptin profile may be related to hyperprolactinemia, hypogonadism or lack of hyperinsulinemia. Molecular Psychiatry (2000) 5, 70-76.

Body weight gain induced by antipsychotic drugs: mechanisms and management

Long-term administration of typical and atypical antipsychotic drugs (AP) induces excessive weight gain which afflicts up to 50% of patients, impairs health and interferes with treatment compliance. Basic and clinical research has shown that AP may affect body weight through diverse mechanisms. Increased appetite is probably related to the interaction of AP with neuronal receptors to dopamine, serotonin and histamine. Additional metabolic-endocrine disruption of weight regulation may be related to the effects of AP-induced hyperprolactinaemia on gonadal-adrenal steroids and insulin sensitivity. In humans, programmed physical activity, dietary restriction, anorectic agents, and drugs that counteract hyperprolactinaemia have been shown to be successful in a limited number of studies. Two novel strategies could expand the available therapeutic options. First, in preclinical experiments in female rats the estradiol antagonist/agonist drug tamoxifen or estradiol itself have been shown to completely prevent the obesity provoked by the AP sulpiride, and to induce an endocrine-metabolic milieu that seems to counteract AP-induced obesity. Secondly, it has also been shown that oral antihyperglycaemic agents such as metformin may decrease body weight and counteract insulin resistance and hyperinsulinaemia which is correlated with several metabolic abnormalities in obese subjects. Lastly, estradiol replacement, tamoxifen and/or antihyperglycaemic agents are not devoid of significant side-effects, and these drugs have not been tested in obese psychiatric patients. Therefore, further research is needed before their clinical use may be recommended.

Antipsychotic drugs and reproductive hormones: relationship to body weight regulation

Excessive body weight gain is an undesirable side effect of prolonged administration of antipsychotic drugs (AP), which affects health and interferes with treatment compliance. It has been suggested that hyperprolactinemia-induced endocrine and metabolic abnormalities, particularly in the gonadal steroids, might be involved in the development of this type of weight gain. To test this hypothesis, reproductive hormones, cortisol, dehydro-epiandrosterone-sulfate (DHEA-S), thyroid hormones, and body weight gain were assessed in 18 patients (9 men, 9 women) with mental disorders receiving AP who had been medication-free for at least 3 months before the study, and in 27 placebo-treated subjects (10 men, 17 women). In women, hormones were evaluated during several phases of the menstrual cycle. A significant weight gain was observed in men but not in women. Under AP administration, women displayed significantly lower serum levels of estradiol and progesterone, whereas in men the levels of free testosterone and DHEA-S were significantly lower than in controls. Hyperprolactinemia was observed in both sexes. The levels of follicle-stimulating hormone in women and luteinizing hormone in men were significantly elevated by treatment, thus suggesting that the functioning of the hypothalamus-pituitary gonads was preserved. In men, such an endocrine profile resembles that observed in subjects with primary obesity. Women under AP administration were found to be relatively hyperandrogenic because of decreased serum estradiol levels, whereas women with primary obesity are known to display actual increased levels of androgens. These endocrine abnormalities may contribute to the excessive weight gain observed after AP treatment, and these could be the target of novel pharmacological treatments.

Glucose tolerance and serum insulin levels in an animal model of obesity induced by sub-acute or chronic administration of antipsychotic drugs

1. To assess the role of insulin in the development of the obesity induced by antipsychotic drugs, a glucose tolerance test was conducted in female rats after 0 or 30 days of sulpiride administration. 2. At day 10, the area under the glucose curve did not differ between sulpiride and vehicle-treated rats, however, the area under the insulin curve was significantly decreased by sulpiride. At day, 30 the insulin response was similar in both groups, but the area under the glucose curve was significantly lower in the sulpiride-treated rats. 3. The results suggest that insulin resistance and hyperinsulinemia are not involved in the development and maintenance of the obesity induced by sulpiride. Contrarily, these findings may be related to an increased insulin sensitivity. 4. The absence of hyperinsulinemia and insulin resistance indicates important differences between primary obesity in humans and rodents and this model of drug-induced excessive weight gain.

Glucose tolerance and serum insulin levels in an animal model of obesity induced by the antipsychotic drug, sulpiride

To assess the role of insulin in the development of obesity induced by antipsychotic drugs, a glucose tolerance test was conducted in 40 female rats during the peak of sulpiride-induced weight gain and in 40 vehicle-treated animals. The glucose area under the curve did not differ between the groups (P = 0.24), however, the area under the insulin curve was significantly decreased by sulpiride (55.2 +/- 2.8 versus 115.6 +/- 18.9, P = 0.007). The results suggest that insulin resistance and hyperinsulinaemia are not involved in the excessive weight gain observed in this animal model of drug-induced obesity. Alternatively, the insulin-dampened response observed in the sulpiride-treated rats may be related to increased insulin sensitivity, which may promote weight gain as proposed by Ravussin (1995).

Congenital neuroblastoma in a boy born to a woman with bipolar disorder treated with carbamazepine during pregnancy

1. A metastatic neuroblastoma was detected immediately after birth in a boy born to a 26 year old woman with bipolar disorder, who received carbamazepine (400 mg/day) all through her pregnancy. The primary tumor was probably located in the adrenal gland of the right side, and multiple metastatic lesions were detected in the skin. 2. In this report the authors review the literature about the side effects teratogenic and carcinogenic effects of carbamazepine, the epidemiology and evolution of the neuroblastoma, and the current scientific opinion about the pharmacological treatment of the pregnant with mood disorders. 3. A causal relationship between the use of carbamazepine and the neuroblastoma development in the present case can not be established; however, as the carcinogenic and teratogenic effects of the drug have been basically assessed in epileptic women, our aim is to alert the medical community in order to conduct further research in psychiatric patients.

Mechanism of the neuroleptic-induced obesity in female rats

1. Obesity is an undesirable side effect of neuroleptics which affects 50% approximately of patients under a program of chronic administration. 2. An animal model of neuroleptic-induced obesity and hyperphagia has been developed in female rats treated chronically with sulpiride (20 mg/Kg/ip. for 21 days). However, it is unknown whether or not the hyperphagia is essential for the development of this type of obesity. 3. Sulpiride or vehicle was administered in two experimental conditions: in the first one, food was available in an amount which was three times the previous individual daily food intake; in the second one, the daily food provision was maintained at the individual daily average before starting the treatments. This way hyperphagia was prevented in half of the groups. Besides the body weight gain measurement in all the groups, the serum levels of estradiol, prolactin, glucose and lipids were assessed in the groups with unrestricted food intake. 4. Food restriction prevented the sulpiride-induced weight gain, even though the rats displayed a permanent diestrus which suggests an hyperprolactinemia-induced impairment in the balance of the reproductive hormones that may promote weight gain. However, the basal levels of estradiol were not affected by sulpiride. 5. The high density cholesterol was significantly increased by sulpiride, and the serum glucose levels were significantly decreased, however these changes were only detected during the first week of treatment. 6. The decrease in the serum glucose levels may be an early consequence of hyperinsulinemia. 7. Neuroleptic-induced obesity in rats appears to mimic energy intake, endocrine status and carbohydrate metabolism in humans under chronic neuroleptic administration. However, these rodents did not display the typical changes in blood lipids observed in human obesity.

Effects of the antipsychotic drug sulpiride on reproductive hormones in healthy premenopausal women: relationship with body weight regulation

Metabolic and endocrine abnormalities secondary to hyperprolactinemia, such as hypogonadism and hyperandrogenicity, may be involved in the excessive body weight gain induced by antipsychotic drugs in women. The present study was conducted in healthy premenopausal women, in order to detect an endocrine imbalance secondary to antipsychotic drug administration, which, if sustained in the long term, might be involved in the development of obesity. After a control menstrual cycle, sulpiride (200 mg/day) or placebo was nonblindly administered for 28 days; blood lipids and the serum levels of the following hormones which are involved in body weight regulation were assessed at days 3, 10, 20 and 26 of the cycle: prolactin (PRL), 17-beta estradiol (E2), progesterone (P4), follicle stimulating hormone (FSH), luteinizing hormone (LH), free testosterone (T5), dehydroepiandrosterone sulfate (DHEAS), cortisol, tyrotropic hormone (TSH), tetraiodothyroxine (T4), and the areas under the insulin and glucose tolerance curve. During sulpiride administration, the following changes were observed when compared to placebo administration: PRL levels were significantly increased; E2 levels were significantly reduced at days 10 and 20; P4 levels were significantly reduced at day 20, and the area under the glucose tolerance curve was significantly increased. The other variables were not significantly affected. The body weight gain was higher during sulpiride than during placebo administration, but it did not reach statistical significance, perhaps because the period of treatment was too short. The decrease in the serum levels of E2 during sulpiride administration is probably secondary to hyperprolactinemia. It affects the E2/T5 ratio in the direction of increasing the androgenic activity, as observed in women with well-established obesity. This effect, along with a genetic predisposition, increased appetite, hypoactivity and ignorance of proper dietary habits, may explain the excessive weight gain and obesity observed in women during chronic treatment with sulpiride and other antipsychotic agents.

Effects of the antipsychotic drug sulpiride on reproductive hormones in healthy men: relationship with body weight regulation

Metabolic and endocrine abnormalities secondary to hyperprolactinemia, particularly hypogonadism, may be involved in the excessive body weight gain observed during treatment with antipsychotic drugs. The present study was conducted in healthy men in order to detect an endocrine imbalance secondary to antipsychotic drug administration, which, if sustained in the long term, might be involved in the development of obesity. Sulpiride (200 mg daily for 30 days) or placebo was nonblindly administered, and body weight gain was correlated with the serum levels of prolactin, luteinizing hormone, follicle-stimulating hormone, estradiol, free testosterone, thyrotropic hormone, free tetraiodothyroxine, cortisol, dehydroepiandrosterone sulphate (DHEA-S), and the ratios estradiol/testosterone and testosterone/DHEA-S; the blood lipids were also assessed. Body weight gain and the serum levels of prolactin were significantly increased by sulpiride; in addition, a significant positive correlation was observed between prolactin levels and body weight gain. Other endocrine parameters were not significantly affected by the drug. These short-term results show that in healthy men, body weight can be increased by antipsychotic drug administration; this effect may be related to hyperprolactinemia alone, since other endocrine parameters were normal at the time of treatment. A more prolonged treatment with antipsychotic agents might be required to observe the alterations in gonadal and adrenal steroids often detected in subjects with primary obesity.

Effects of lithium carbonate on reproductive hormones in healthy men: relationship with body weight regulation--a pilot study

1. To test the hypothesis that lithium-induced body weight gain is related to an unbalance in the reproductive hormones, lithium carbonate (900 mg/day) or placebo was administered to healthy men for 1 month. 2. Body weight, skin folds and the serum levels of thyrotropic hormone, tetraiodothyroxine, prolactin, follicle-stimulating hormone, luteinizing hormone, testosterone (T5), dehydroepiandrosterone sulfate (DHEAS), estradiol (E2), cortisol, the ratios E2/T5 and T5/DHEA-S, and blood lipids were evaluated before and during treatment. 3. Body weight, skin folds, hormones and lipids serum levels were not significantly affected by the treatment with Li. These results agree with previous reports of lack of effects of 1 month-Li administration on appetite and body weight in normal male subjects (Chen et al., 1992), and question the appropriateness of studying Li-induced obesity in healthy volunteers, given the short-term administration and low doses of Li that must be used.

Tamoxifen prevents sulpiride-induced weight gain in female rats

To evaluate its potential utility in counteracting neuroleptic-induced obesity, the effects of long-term administration of tamoxifen (TAM) on body weight (BW) and food intake (FI) of gonadally intact and sulpiride-treated (SUL) female rats were assessed. In addition, estradiol and prolactin serum levels were measured in rats treated with SUL. SUL plus TAM and SUL plus bromocriptine (BR). TAM, at doses of 10, 50 and 100 micrograms, significantly decreased BW gain: FI was significantly reduced at the doses of 50 and 100 micrograms. In addition, doses of TAM ranging from 5-100 micrograms completely prevented SUL-induced BW gain and hyperphagia. BR also prevented SUL effects on BW and FI. In contrast to BR, concomitant administration of TAM did not prevent SUL-induced hyperprolactinemia. Estradiol levels were not modified by SUL alone or SUL plus BR, but they were significantly increased in the animals treated with TAM plus SUL. Neuroleptic-induced obesity in female rats might be related to an alteration in gonadal steroid balance secondary to hyperprolactinemia. While BR might counteract neuroleptic-induced weight gain by preventing hyperprolactinemia, TAM might directly interact with estrogen receptors, or indirectly increase estradiol levels. The use of TAM in preventing neuroleptic-induced obesity in humans warrants further investigation.

Amantadine in the treatment of neuroleptic-induced obesity in rats: behavioral, endocrine and neurochemical correlates

The efficacy of the antiviral agent Amantadine (AM, 5-100 mg/kg/sc, ip or intrahypothalamically, 12.5-100 micrograms bilaterally) in influencing body weight and food intake in drug-free rats, and in preventing neuroleptic-induced weight gain, was assessed in adult female rats. In drug-free rats, acute administration of systemic AM or directly injected in the lateral hypothalamus (LH) displayed a significant dose-dependent anorectic effect (p < 0.001). This effect could be mediated by the brain monoaminergic system, because systemic or local injections of AM increased dopamine and serotonin overflow in the nucleus accumbens and in the LH. Chronic administration of AM significantly decreased body weight gain in drug-free rats only at the dose of 100 mg/kg/sc. Similarly, obesity induced by the neuroleptic drug sulpiride (SUL, 20 mg/kg/ip for 21 days) was prevented by AM only at the dose of 100 mg/kg. AM did not prevent SUL-induced hyperprolactinemia, disruption of the vaginal cycle and a decrement in the weight of the uterus and ovaries at any dosage. This lack of efficacy of AM contrasts with that of bromocriptine, which completely prevented SUL-induced weight gain and hyperprolactinemia. The results show that despite a potent acute anorectic effect, AM displays a weak antagonistic action on SUL-induced obesity in rats, in contrast to the preliminary results obtained in humans. As AM metabolism differs in humans and rats, additional research is needed before its systematic testing in counteracting neuroleptic-induced obesity in patients with mental disorders.

Systemic and local cocaine increase extracellular serotonin in the nucleus accumbens

The effect of systemic or intra-accumbens injections of cocaine on serotonin (5-HT) overflow was studied by nucleus accumbens microdialysis in freely moving rats. In Experiment 1, cocaine was injected intraperitoneally at 0, 10, 20, and 30 mg/kg. In Experiment 2, cocaine (3.6, 7.2, and 14.4 mM), lidocaine (7.2 mM), or saline was infused through the probe by reverse microdialysis. Extracellular serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) were measured by high-pressure liquid chromatography and electrochemical detection. Systemic administration of cocaine induced a dose-related increase in 5-HT overflow and a decrease of 5-HIAA. Intra-accumbens cocaine infusion also caused a dose-related increase in 5-HT, but no effect on 5-HIAA. As a control for local anesthesia, equimolar lidocaine did not increase 5-HT. The difference between lidocaine and cocaine was not due to unequal diffusion out of the probe, because previous in vivo calibration of the probe showed that more lidocaine than cocaine diffused out of the probe when equimolar solutions were infused. These experiments suggest that systemic cocaine acts on the nucleus accumbens to increase synaptic 5-HT.

The teaching of the biological basis of psychiatry

1. What is usually taught as biological psychiatry in psychiatric residency training is mainly psychopharmacology, but biology has a lot more to offer to psychiatry educators. 2. The main thesis of this article is that an introductory course on the applications to psychiatry based on the theory of the evolution of the species by natural selection and mutation, along with a comprehensive theory of mind, may contribute to: (i) helping young physicians to integrate the diverse and extensive knowledge acquired during the residency training; (ii) aid in keeping the psychiatrist within the medical approach to mental illnesses while promoting the specific features of the specialty, and (iii) perhaps developing a general theoretical framework that allows psychiatrists to maintain a prominent role in the mental health staff. 3. The author describes how he has conducted such training in Venezuela. It is expected that the author's ideas will serve as a forum for discussion of this pivotal subject.

Lithium and body weight gain

Weight gain is an undesirable side-effect of long-term lithium administration which notably interferes with treatment compliance. The mechanisms of this weight gain remain unclear, making its management in patients difficult. In this paper, studies describing the features of this weight gain in patients and in rats treated with chronic lithium administration are reviewed. The effects of lithium on body weight differ between patients and rats in a number of ways, including the observation that excessive weight gain is observed in both male and female patients, but only in female rats. Nevertheless, an animal model of lithium-induced weight gain may be able to provide useful insights into some of the specific mechanisms involved, particularly those related to interactions with gonadal steroid function. We discuss the effects of lithium on the endocrine system, neurotransmitters, metabolism, electrolyte regulation, and feeding behavior, which might underlie lithium's effects on body weight. Finally, suggestions for the management of weight gain in the clinical setting are presented. These include, in the long term, dietary control and physical activity and, in the short term, choosing among several drugs that have been tested either in patients or in animal models of obesity. If weight gain still cannot be controlled and treatment compliance is at risk, the mood stabilizers carbamazepine or valproic acid might be substituted for lithium treatment.

Hyponatremia and neuroleptic-induced obesity in rats

The weight gain and hyperphagia induced by chronic administration of sulpiride in female rats were not prevented by the concomitant administration of an extra source of sodium. In addition, serum sodium levels were not affected, but potassium levels were significantly reduced by sulpiride administered for 1 week. These results suggest that sulpiride-induced obesity in rats is not related to sodium imbalance. The mechanism for the decrease in serum potassium levels and its relation with sulpiride-induced weight gain warrant further investigation.

Testosterone modulates mesolimbic dopaminergic activity in male rats

Male rats were castrated before puberty. When they were adult, the activity of their mesolimbic dopamine system was tested by ventral striatum microdialysis. Amphetamine injections increased dopamine more in castrated rats than in normal rats. This exaggerated response was attenuated by testosterone replacement therapy. The mechanism by which androgens modulate the activity of the mesolimbic dopamine system is discussed.

Electrical kindling is associated with increases in amygdala acetylcholine levels: an in vivo microdialysis study

Using brain microdialysis, acetylcholine (Ach) levels were assessed in the nucleus amygdaloideus lateralis of electrically kindled rats using a cholinesterase inhibitor in the perfusion fluid to prevent Ach breakdown. During kindling development, when the animals displayed afterdischarges lasting more than 30 s but no seizures, a significant increase in Ach levels (+66%) was observed after electrical stimulation. Ach levels were also elevated after a stage 5 kindled seizure (+48%), with no additional increment compared to rats experiencing only afterdischarges. Chronic diazepam administration prevented kindling development and the increment in Ach overflow; however, diazepam itself (following acute administration) tended to decrease Ach levels in the amygdala. These findings are convergent with pharmacological data suggesting that changes in the cholinergic function may be important especially during amygdaloid kindling development.

Dopamine increase in the prefrontal cortex correlates with reversal of haloperidol-induced catalepsy in rats

The mechanism by which forced swimming reverses, haloperidol-induced catalepsy was examined by measuring dopamine (DA) turnover in the nucleus accumbens-ventromedial caudate (NAC-C) and the prefrontal cortex (PFC) in rats. DA and its metabolites 3,4-dihydroxiphenylacetic acid (DOPAC) and homovanillic acid (HVA) were assessed by microdialysis and high pressure liquid chromatography with electrochemical detection (HPLC-ED) after systemic administration of a cataleptic dose of haloperidol (5 mg/kg) or saline. Haloperidol-induced catalepsy was temporarily suppressed by forced swimming. Haloperidol-treated rats showed an increase of DA, DOPAC, and HVA overflow in the PFC and the NAC-C. This increase was greater in the PFC of rats that were forced to swim. Rats that were not treated with haloperidol but were forced to swim (control group) showed an increase of DA, DOPAC, and HVA in the PFC but not in the NAC-C. Zero micrograms, 5 micrograms, 10 micrograms, and 20 micrograms of DA was bilaterally injected in the PFC of cataleptic rats to evaluate the hypothesis that DA in the PFC reverses catalepsy. Haloperidol-induced catalepsy was diminished by bilateral microinjections of 10 micrograms and 20 micrograms but not by 5 micrograms of DA in the PFC. The higher the dose of DA, the longer the decrease of catalepsy. These results suggest that an increase of DA turnover in the PFC might mediate temporal suppression of haloperidol-induced catalepsy. The mechanism by which the mesocortical DA system reduces catalepsy is discussed.

Substance use among Venezuelan medical and pharmacy students

The frequency of substance use disorders and non-pathological use of drugs was assessed in a cohort of undergraduate medical (N = 1013) and pharmacy students (N = 426) from the University of the Andes (Mérida, Venezuela). The survey was conducted using a self-administered Spanish version of the Diagnostic Interview Schedule (DIS-III-A). It was found that the lifetime frequency of substance use disorders was significantly higher in medical than in pharmacy students, but this difference disappeared when the sex was controlled. Substance use disorders were more common in single males and most cases were observed in subjects in their intermediate academic semesters. It was also found that the frequency of non-pathological use of drugs was higher in medical than in pharmacy students and in men than in women. The frequency of substance use disorders in our sample was smaller than that reported in American surveys of substance misuse among medical and pharmacy students. However, because of methodological differences these comparisons are questionable. Our results suggest that Venezuelan medical students are not at an unusually high risk of substance misuse when compared with pharmacy students whose reputedly low levels of substance use are often contrasted with those of the medical profession.

The attitudes toward psychiatry of physicians and medical students in Venezuela

Attitudes toward psychiatry were assessed in 490 medical students and 362 physicians from two universities in Venezuela: Universidad de Los Andes (ULA) and Universidad Centro-Occidental Lisandro Alvarado (UCLA). A modified version of the Attitude Toward Psychiatry-30 scale was used. The attitude toward psychiatry of all the students and physicians was moderately positive. Students from ULA displayed a more positive attitude than UCLA students, whereas physicians from UCLA displayed a more positive attitude than ULA physicians. The most negative attitude toward psychiatry was observed in students planning to select obstetrics and gynecology (ULA + UCLA), in physicians working in Surgery, obstetrics and gynecology (ULA + UCLA) and in basic sciences (ULA). Female students tended to display a more positive attitude than male students. The attitude toward psychiatry was similar in students with low and high academic achievement in the courses in psychiatry. A large number of years in the profession did not modify the attitude of the physicians. It is recommended to improve teaching and communication with the students and physicians that displayed the most negative attitudes toward psychiatry.

Effects of acute and chronic lithium treatment on amphetamine-induced dopamine increase in the nucleus accumbens and prefrontal cortex in rats as studied by microdialysis

The effects of acute and chronic administration of lithium (Li) on the basal levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-indoleacetic acid (5-HIAA), and the amphetamine-induced DA increase were assessed in the Nucleus Accumbens (NAC) and Prefrontal Cortex (PFC) by brain dialysis in freely-moving rats. Acute Li (2 meq/L) was locally administered by reverse dialysis. Chronic Li (2 meq/kg) was intragastrically administered for 14 days. No effect was observed after acute Li administration. However, after chronic Li administration, the basal levels of DOPAC and the amphetamine-induced DA increase in the NAC were significantly higher in the Li-treated rats than in the saline-treated controls. In the PFC, while the amphetamine-induced DA increase was not affected by chronic Li, the basal levels of DA and DOPAC were significantly decreased after Li administration. The effects of chronic Li in the NAC could be due to increased synthesis and/or decreased release of DA, whereas in the PFC the effects could be due to a decreased synthesis of DA. The absence of effects of acute Li administration is in agreement with the therapeutic inefficacy of the acute use of the cation. The changes observed after chronic treatment in the NAC and the PFC could be related to the effects of Li on mood disorders and cognitive functions, respectively.

Carbamazepine attenuates cocaine-induced increases in dopamine in the nucleus accumbens: an in vivo dialysis study

Carbamazepine's effects on cocaine-induced increases in dopamine overflow in the nucleus accumbens were studied using in vivo microdialysis in anesthetized rats. Rats were chronically treated with a diet containing carbamazepine or no drug for one week prior to microdialysis procedures. The basal levels of dopamine in the nucleus accumbens did not differ between groups; however, the increases in dopamine following cocaine administration (4 mg/kg i.v.) were significantly reduced by carbamazepine. In addition, basal levels of dihydroxyphenyl acetic acid (DOPAC) were significantly diminished in the carbamazepine group and a trend in the same direction was observed for homovanilic acid (HVA). These results are consistent with reports that carbamazepine might decrease dopamine synthesis. Further studies are required to determine the mechanism of carbamazepine's inhibition of cocaine-induced dopamine overflow and its potential clinical implications.

Enhancement of amphetamine anorexia after chronic administration of sulpiride in rats

Long-term administration of sulpiride induces hyperphagia and obesity in female rats. After sulpiride withdrawal, a significant hypophagia has been observed. The hyperphagia could be related to the blockade and the hypophagia to supersensitivity of dopamine D2 receptors, in particular those D2 receptors located in the perifornical hypothalamus. If this were the case, an enhancement of anorexia induced by amphetamine and dopamine should be observed after interruption of long-term sulpiride treatment. Two doses of systemic sulpiride (20 or 200 mg/kg) and one dose of intrahypothalamic sulpiride (15 micrograms) were tested. Amphetamine was administered by systemic or intrahypothalamic infusion. Dopamine was administered in the hypothalamus. After withdrawal of systemic administration of sulpiride (200 mg/kg), an enhancement of anorexia induced by systemic amphetamine was observed. However, the anorexia induced by intrahypothalamic injections of amphetamine or dopamine was not affected by the interruption of the sulpiride treatment. These results suggest that the hypophagia following chronic sulpiride treatment is not due to supersensitivity of D2 dopamine receptors in the lateral hypothalamus. Moreover, the change in the response to amphetamine might be related to supersensitivity of extrahypothalamic D2 receptors.

Effects of long-term administration of clozapine on body weight and food intake in rats

Previous reports have shown that long-term administration of typical and atypical neuroleptics induced obesity in female but not in male rats. It has been suggested that impaired ovarian steroidogenesis related to neuroleptic-induced hyperprolactinemia is necessary to observe the body weight changes. This hypothesis was tested with clozapine, an atypical neuroleptic that produces in rats a shorter increase in serum prolactin levels than do other neuroleptics. The effects of clozapine on body weight and food intake were assessed in female and male rats under treatment with any of the following doses: 0.5, 1, 2.5, 5, 10, and 20 mg/kg IP for 21 days. Vaginal cycle under clozapine treatment, as an indirect indicator of ovarian steroidogenesis, was also assessed. Obesity was not observed in any group. By contrast, clozapine at the doses of 10 and 20 mg/kg significantly decreased body weight and feeding in male rats. Clozapine at the doses of 5 and 10 mg/kg IP induced permanent diestrus. The failure of clozapine to induce obesity in female rats, despite impaired vaginal cycle, can be considered indirect evidence that drug-induced hyperprolactinemia is not sufficient to observe neuroleptic-induced obesity in rats.

Substance use among resident doctors in Venezuela

This study was aimed to develop a self-administered questionnaire to detect substance use disorders based on the Spanish version of the Diagnostic Interview Schedule (DIS) and to evaluate the frequency of substance abuse and/or dependence among resident physicians of a large university hospital in Venezuela. The questionnaire showed a high concordance with the clinical diagnoses. Frequency of substance abuse and dependence was evaluated among 191 resident doctors. The frequencies of lifetime diagnoses were: tobacco dependence: 20.9%; alcohol abuse: 11%; alcohol dependence: 0.5%; drug abuse: 1% and drug dependence: 1%; non-pathological use of drugs: 20.4%.

Hypothalamic serotonin in treatments for feeding disorders and depression as studied by brain microdialysis

Microdialysis was used to measure changes in extracellular serotonin in the hypothalamus of rats while they engaged in feeding behavior or received drug treatments used to treat feeding disorders and affective disorders in humans. Hypothalamic serotonin increased significantly relative to controls in response to (1) intraperitoneal tryptophan after food deprivation, (2) the smell of food and eating a meal, (3) a conditioned taste aversion, (4) d-fenfluramine and fluoxetine, and (5) an amphetamine challenge test after chronic low doses of lithium. In some cases, increases correlated with nonspecific behavioral arousal were seen in the hippocampus. The results suggest that diet, drug, and behavioral therapies, alone or combined, can be used to preferentially modify hypothalamic serotonin in the control of behavioral, emotional, and endocrine problems.

Hypothalamic sites affecting masticatory neurons in rats

The effects of hypothalamic electrical stimulation and dl-sulpiride injections on the unit activity of masticatory trigeminal neurons were assessed in rats. Unilateral electrodes or bilateral cannulas were implanted in the perifornical hypothalamus. The animals which exhibited eating to electrical stimulation or to sulpiride injections were selected. Then, under urethane anesthesia, electrical stimuli or sulpiride injections were applied at sites which elicited eating while a passive jaw movement-related neuron was recorded. Electrical stimulation or sulpiride injections affected the basal firing rate of 15 out of 32 (53%), and 13 out of 17 (76%) jaw movement-related neurons, respectively. The basal firing rate of 3 out of 18 (16.6%) was affected by electrical stimulation of noneliciting feeding nearby places. Facilitation was observed in 7 out of those 13 jaw movement-related trigeminal neurons after intrahypothalamic sulpiride injections. When dopamine was injected in the hypothalamus 3 minutes before sulpiride, this drug could only affect the basal firing rate of 1 out of 12 (8%) jaw movement-related neurons. The electrical stimulation and sulpiride injections into the hypothalamus had the same inhibitory or excitatory effect on a given trigeminal neuron as the passive jaw movement did. A similar phenomenon was observed with the sulpiride-induced facilitation. These results suggest that hypothalamic D2 satiety receptors modulate brain stem feeding reflexes.

Mechanism of the sex-dependent effect of lithium on body weight in rats

Two experiments are reported here. First, the effect of lithium chloride (1, 2 and 4 mEq/kg IP for 21 days) on body weight was assessed in female and male rats. Food intake was measured in the rats treated with 2 mEq/kg. All the doses tested significantly increased body weight in female rats. A linear relationship between body weight gain and lithium dose was also observed. In contrast, in male rats, the low doses of lithium (1 and 2 mEq/kg) did not affect body weight, whereas the high dose (4 mEq/kg) decreased body weight. These results confirm previous reports on a sex-dependent effect of lithium on body weight in rats. In the second experiment, body weight and food intake were assessed in female rats treated with lithium alone, or in combination with insulin or sulpiride, a D2 dopamine receptor blocker. It was found that the effect of lithium on body weight and feeding was additive to the effects of sulpiride and insulin. These findings are indirect evidence that lithium enhances body weight in rats by a different mechanism than the one described for sulpiride or insulin.

Systemic sulpiride increases dopamine metabolites in the lateral hypothalamus

In rats with microdialysis probes in the perifornical lateral hypothalamus (PFH) a single injection of the D2 receptor blocker 1-sulpiride (20 mg/kg IP) significantly increased extracellular dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), but not 5-hydroxyindoleacetic acid (5-HIAA). This suggests that sulpiride crosses the blood-brain barrier and blocks D2 dopamine receptors in the PFH leading to increased dopamine turnover reflected in increased extracellular DOPAC and HVA. We conclude that D2 blockade in the hypothalamus could play a role in the hyperphagia and body weight gain observed in female rats under chronic administration of the antipsychotic drug, sulpiride.