Behavioral effects of endogenous or exogenous estradiol and progesterone on cocaine sensitization in female rats

Cocaine sensitization is a marker for some facets of addiction, is greater in female rats, and may be influenced by their sex hormones. We compared the modulatory effects of endogenous or exogenous estradiol and progesterone on cocaine-induced behavioral sensitization in 106 female rats. Ovariectomized female rats received progesterone (0.5 mg/mL), estradiol (0.05 mg/mL), progesterone plus estradiol, or the oil vehicle. Sham-operated control females received oil. Control and acute subgroups received injections of saline, while the repeated group received cocaine (15 mg/kg, ip) for 8 days. After 10 days, the acute and repeated groups received a challenge dose of cocaine, after which locomotion and stereotypy were monitored. The estrous cycle phase was evaluated and blood was collected to verify hormone levels. Repeated cocaine treatment induced overall behavioral sensitization in female rats, with increased locomotion and stereotypies. In detailed analysis, ovariectomized rats showed no locomotor sensitization; however, the sensitization of stereotypies was maintained. Only females with endogenous estradiol and progesterone demonstrated increased locomotor activity after cocaine challenge. Estradiol replacement enhanced stereotyped behaviors after repeated cocaine administration. Cocaine sensitization of stereotyped behaviors in female rats was reduced after progesterone replacement, either alone or concomitant with estradiol. The behavioral responses (locomotion and stereotypy) to cocaine were affected differently, depending on whether the female hormones were of an endogenous or exogenous origin. Therefore, hormonal cycling appears to be an important factor in the sensitization of females. Although estradiol increases the risk of cocaine sensitization, progesterone warrants further study as a pharmacological treatment in the prevention of psychostimulant abuse.

Influence of progesterone on GAD65 and GAD67 mRNA expression in the dorsolateral striatum and prefrontal cortex of female rats repeatedly treated with cocaine

Female rats are intensely affected by cocaine, with estrogen probably playing an important role in this effect. Progesterone modulates the GABA system and attenuates the effects of cocaine; however, there is no information about its relevance in changing GABA synthesis pathways after cocaine administration to female rats. Our objective was to investigate the influence of progesterone on the effects of repeated cocaine administration on the isoenzymes of glutamic acid decarboxylase (GAD65 and GAD67) mRNA in brain areas involved in the addiction circuitry. Ovariectomized, intact and progesterone replacement-treated female rats received saline or cocaine (30 mg/kg, ip) acutely or repeatedly. GAD isoenzyme mRNA levels were determined in the dorsolateral striatum (dSTR) and prefrontal cortex (PFC) by RT-PCR, showing that repeated, but not acute, cocaine decreased GADs/β-actin mRNA ratio in the dSTR irrespective of the hormonal condition (GAD65: P < 0.001; and GAD67: P = 0.004). In the PFC, repeated cocaine decreased GAD65 and increased GAD67 mRNA ratio (P < 0.05). Progesterone replacement decreased both GAD isoenzymes mRNA ratio after acute cocaine in the PFC (P < 0.001) and repeated cocaine treatment reversed this decrease (P < 0.001). These results suggest that cocaine does not immediately affect GAD mRNA expression, while repeated cocaine decreases both GAD65 and GAD67 mRNA in the dSTR of female rats, independently of their hormonal conditions. In the PFC, repeated cocaine increases the expression of GAD isoenzymes, which were decreased due to progesterone replacement.

Behavioral changes induced by cocaine in mice are modified by a hyperlipidic diet or recombinant leptin

The objective of the present study was to determine if the acute behavioral effects of cocaine acutely administered intraperitoneally (ip) at doses of 5, 10 and 20 mg/kg on white male CF1 mice, 90 days of age, would be influenced by leptin acutely administered ip (at doses of 5, 10 and 20 æg/kg) or by endogenous leptin production enhanced by a high-fat diet. The acute behavioral effects of cocaine were evaluated in open-field, elevated plus-maze and forced swimming tests. Results were compared between a group of 80 mice consuming a balanced diet and a high-fat diet, and a group of 80 mice fed a commercially available rodent chow formula (Ralston Purina) but receiving recombinant leptin (rLeptin) or saline ip. Both the high-fat-fed and rLeptin-treated mice showed decreased locomotion in the open-field test, spent more time in the open arms of the elevated plus-maze and showed less immobility time in the forced swimming test (F(1,68) = 7.834, P = 0.007). There was an interaction between diets and cocaine/saline treatments in locomotion (F(3,34) = 3.751, P = 0.020) and exploration (F(3,34) = 3.581, P = 0.024). These results suggest that anxiolytic effects and increased general activity were induced by leptin in cocaine-treated mice and that low leptin levels are associated with behavioral depression. Chronic changes in diet composition producing high leptin levels or rLeptin treatment may result in an altered response to cocaine in ethologic tests that measure degrees of anxiety and depression, which could be attributed to an antagonistic effect of leptin.

Effect of pilocarpine mouthwash on salivary flow

Pilocarpine is a cholinergic agonist that increases salivary flow and has been used to treat xerostomia. Oral intake is the most frequent route of administration. Adverse effects are dose-dependent and include sudoresis, facial blushing and increased urinary frequency. The objective of the present study was to evaluate the effects of topical pilocarpine solutions as mouthwashes on salivary flow and their adverse effects on healthy subjects. Forty volunteers received 10 ml 0.5, 1 and 2 percent pilocarpine solutions or 0.9 percent saline in a randomized, double-blind, placebo-controlled manner. Salivation was measured before and 45, 60 and 75 min after mouth rinsing for 1 min with 10 ml of saline or pilocarpine solutions. Vital signs were measured and ocular, gastrointestinal and cardiovascular symptoms, anxiety and flushing were estimated using visual analog scales. There was a dose-dependent increase in salivation. Salivation measured after 1 and 2 percent pilocarpine (1.4 +/- 0.36 and 2.22 +/- 0.42 g, respectively) was significantly (P<0.001) higher than before (0.70 +/- 0.15 and 0.64 +/- 0.1 g), with a plateau between 45 and 75 min. Cardiovascular, visual, gastrointestinal and behavioral symptoms and signs were not changed by topical pilocarpine. Mouth rinsing with pilocarpine solutions at concentrations of 1 to 2 percent induced a significant objective and subjective dose-dependent increase in salivary flow, similar to the results reported by others studying the effect of oral 5 mg pilocarpine. The present study revealed the efficacy of pilocarpine mouthwash solutions in increasing salivary flow in healthy volunteers, with no adverse effects. Additional studies on patients with xerostomia are needed

Plasma insulin levels are increased by sertraline in rats under oral glucose overload

Recognition and control of depression symptoms are important to increase patient compliance with treatment and to improve the quality of life of diabetic patients. Clinical studies indicate that selective serotonin reuptake inhibitors (SSRI) are better antidepressants for diabetic patients than other drugs. However, preclinical trials have demonstrated that not all SSRI reduce plasma glucose levels. In fact, fluoxetine increases and sertraline decreases glycemia in diabetic and non-diabetic rats. In the present study we evaluated plasma insulin levels during fasting and after glucose overload after treatment with sertraline. Adult male Wistar rats were fasted and treated with saline or 30 mg/kg sertraline and submitted or not to glucose overload (N = 10). Blood was collected and plasma insulin was measured. The mean insulin levels were: fasting group: 25.9 + or - 3.86, sertraline + fasting group: 31.10 + or - 2.48, overload group: 34.1 + or - 3.40, and overload + sertraline group: 43.73 + or - 5.14 æU/ml. Insulinemia was significantly increased in the overload + sertraline group. There were no differences between the other groups. No difference in glucose/insulin ratios could be detected between groups. The overload + sertraline group was the only one in which a significant number of individuals exceeded the upper confidence limit of insulin levels. This study demonstrates that sertraline increases glucose-stimulated insulin secretion without any change in peripheral insulin sensitivity

Acute effect of different antidepressants on glycemia in diabetic and non-diabetic rats

Diabetic patients have a 20 percent higher risk of depression than the general population. Treatment with antidepressant drugs can directly interfere with blood glucose levels or may interact with hypoglycemic agents. The treatment of depression in diabetic patients must take into account variations of glycemic levels at different times and a comparison of the available antidepressant agents is important. In the present study we evaluated the interference of antidepressants with blood glucose levels of diabetic and non-diabetic rats. In a first experiment, male adult Wistar rats were fasted for 12 h. Imipramine (5 mg/kg), moclobemide (30 mg/kg), clonazepam (0.25 mg/kg), fluoxetine (20 mg/kg) sertraline (30 mg/kg) or vehicle was administered. After 30 min, fasting glycemia was measured. An oral glucose overload of 1 ml of a 50 percent glucose solution was given to rats and blood glucose was determined after 30, 60 and 90 min. Imipramine and clonazepam did not change fasting or overload glycemia. Fluoxetine and moclobemide increased blood glucose at different times after the glucose overload. Sertraline neutralized the increase of glycemia induced by oral glucose overload. In the second experiment, non-diabetic and streptozotocin-induced diabetic rats were fasted, and the same procedures were followed for estimation of glucose tolerance 30 min after glucose overload. Again, sertraline neutralized the increase in glycemia after glucose overload both in diabetic and non-diabetic rats. These data raise the question of whether sertraline is the best choice for prolonged use for diabetic individuals, because of its antihyperglycemic effects. Clonazepam would be useful in cases with potential risk of hypoglycemia

Pup age and aggressive behavior in lactating rats

High levels of aggressive behaviors against intruders in the nest area are displayed by female rats during the first 10 days after delivery, declining thereafter to very low levels, even though lactation continues. Cross-fostering experiments were undertaken to test the hypothesis that pup age may affect aggression in lactating rats. The behavior of females on the 8th day after delivery when raising fostered 8-day-old pups was compared to that of females on the 8th postpartum day raising older pups (18 days old) for the last 5 days, and females on the 18th day after delivery raising fostered 18-day-old pups were compared to females in the same postpartum period nursing younger pups (8 days of age at the time of the maternal aggression test) for 5 days. Pup retrieval activity and plasma prolactin level were also analyzed. Females on the 8th postpartum day nursing 18-day-old pups were less aggressive than females in the same postpartum period, but with 8-day-old pups. Likewise, females on the 18th postpartum day nursing younger pups were more aggressive and presented higher levels of prolactin than females nursing older pups. Thus, pup development can alter the natural decline of maternal aggressive behavior

Effect of estrogen and neuroleptics on prolactin secretion and immunoreactive prolactin cells

The use of estrogen and dopamine receptor antagonists is associated with elevated prolactin levels and, in rats, chronic estrogen treatment is also associated with lactotroph proliferation. In this study, haloperidol, fluphenazine, sulpiride and metoclopramide, alone or combined with estradiol, were administered to Wistar rats. Pituitary weight, serum prolactin levels and percent of immunoreactive prolactin cells in the anterior pituitary glands were determined at the end of 60 days of treatment. The pituitary weight of rats treated with estrogen alone or in combination with other drugs was significantly higher than the control group. The serum prolactin level was higher than the upper confidence limit in all but three of the 90 treated rats. While in the control group the percent of immunoreactive prolactin cells was 20 per cent, administration of the neuroleptic drugs and metoclopramide increased this percent to approximately 30 per cent, and estrogen alone or in combination with one of the neuroleptic drugs increased it to approximately 40 per cent. The results presented here demonstrate the elationship between prolactin secretion and prolactin cell number when different neuroleptics and related drugs are used.

Serviço de informaçoes sobre substâncias psicoativas. Caraterísticas da informaçao sobre drogas / Psychoactive substances information service. Characteristics of the provision of drug information

Este trabalho apresenta a an lise das consultas realizadas a um serviço de informaçöes sobre substâncias psicoativas, em 42 meses de funcionamento. As 1.284 consultas foram feitas através de uma linha telef"nica, havendo contato direto com um plantonista, com manutençäo do anonimato, caso houvesse interesse do usu rio. Constatou-se que, apesar de ampla variaçäo no número de consultas por período, dependendo da divulgaçäo da existência do serviço, a média é de 1,5 consultas ao dia. Näo h preferência entre os sexos e o uso é näo profissional na maioria das perguntas. Questöes sobre drogas de abuso (inalantes e maconha) säo mais frequentes, havendo interesse na obtençäo de mais informaçöes sobre medicamentos prescritos (benzodiazepínicos e antidepressivos), tanto de açäo central como de outros tipos (drogas cardiovasculares e antimicrobianos). É pequeno o número de perguntas sobre cafeína, nicotina e alucinógenos

Effect of sodium valproate on the open-field behavior of rats

It has been reported that sodium valproate induces a morphine-like withdrawal syndrome in rats. The effects of acute or chronic treatment with sodium valproate on rat behavior was studied in the open-field test. Acute sodium valproate (320 mg/kg, intraperitoneally) decreases the freuqncy of, and the time spent in grooming even when not modifying locomotion, rearing or defecation (N=15), either 15 or 60 min after an acute treatment. This effect was not modified (n+10) by concomitant administration of morphine (2 mg/kg) or naloxone (1 mg/kg). Interruption of prolonged (30 days) valproate treatment with increasing doses of 40 to 320 mg/kg, by gavage, twice daily (N=10) did not modify raty behavior in the open-field, from the first to the fourtheenth day of th test. We conclude that the decreased novely-induced grooming does not depend on the opioid system and may be related to anti-anxiety effect of valproate

Effects of phenylethylamine on rat locomotor behavior and avoidance learning

1. The effects of ß-phenylethylamine (PEA) alone and in association with caroxazone, a potent inhibitor of monoamine oxidase B (MAO B), on the activity and long-term memory in the wheel-shaped activity monitor and on fixed-interval two-way avoidance acquisition were studied in rats. In a separate study, we determined the effects of PEA and of d-amphetamine on the variable-internal two-way avoidance acquisition. 2. The action of PEA was markedly different from that of aplhetamine in several aspects. The stimulating effects of PEA in the wheel-shaped activity monitor were of a more subtle nature than those of amphetamine and in the variable-interval two-way avoidance acquisition PEA had no effect, while amphetamine improved performance. 3. PEA did not induce an increase in path-choice stereotypy, but caroxazone did. The absence of any caroxazone-session interaction effects on the path interation frequency suggested that there were no long-term memory effects. 4. In the fixed-interval two-way avoidance acquisition experiments, PEA increased the avoidance responses of tats while caroxazone had no effect. The association of the two drugs did not potenciate either