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Neurofunctional Effects in Rats Prenatally Exposed to Fluoxetine

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Neurofunctional Effects in Rats Prenatally Exposed to Fluoxetine European Review for Medical and Pharmacological Sciences 2008; 12: 137-148 Neurofunctional effects in rats prenatally exposed to fluoxetine R. CAGIANO, P. FLACE3, I. BERA1, L. MARIES1, G. CIOCA1, R. SABATINI4, V. BENAGIANO3, P. AUTERI5, A. MARZULLO6, D. VERMESAN2, R. STEFANELLI7, G. AMBROSI3 Department of Pharmacology and Human Physiology, Medical Faculty, University of Bari (Italy) 1 “Lucian Blaga” University, Medical School, Sibiu (Romania) 2 University of Medicine and Pharmacy ”Victor Babes”, Timisoara (Romania) 3 Department of Human Anatomy and Histology, Medical Faculty, University of Bari (Italy) 4 Department of Obstetrics and Gynecology, Medical Faculty, University of Bari (Italy) 5 Department of Ophthalmology, General Hospital, Matera (Italy) 6 Department of Pathological Anatomy and Genetics, Medical Faculty, University of Bari (Italy) 7 Department of Medical Biochemistry, Biology and Physics, Medical Faculty, University of Bari, (Italy) Abstract. – In the treatment of depression F10 = Fluoxetine 10 mg/kg fluoxetine [a selective serotonine reuptake in- M/IL = Mount/intromission latency hibitor (SSRIs)] is a widely used drug in hu- M/IF = Mount/intromission frequency mans. The selectivity, efficacy, side effects and simplicity of dosage contributed to fluoxetine’s EjL = Ejaculation latency clinical acceptance. Several psychiatric disor- EjF = Ejaculation frequency ders (many of them responsive to SSRIs) are PEjI = Post-ejaculatory interval present during pregnancy; up to 10% of preg- L50 = Latency to the first 50 kHz call nant women fulfill diagnostic criteria for major L22 = Latency to the first 22 kHz call or minor depression with an even higher per- D22 = Duration of the post-ejaculatory 22 kHz centage developing postpartum depression. vocalization Therefore, significant numbers of women may be taking SSRIs while pregnant. Since fluox- etine’s safe use during pregnancy is not yet es- tablished and experimental studies inconclu- sive, we performed the present research in order Introduction to investigate the neurobehavioral effects pro- duced in rats by prenatal exposure to fluoxetine Starting from 1988, fluoxetine has been the (5 and 10 mg/kg/sc from day 13 to 20 of gesta- tion) on cognitive functions, emotional reactivity first selective serotonine reuptake inhibitor (SS- and sexual performance. RIs) effective in the treatment of depression. Among the serotonin (5-HT) uptake inhibitors, Key Words: fluoxetine seems to possess the lowest rate of Fluoxetine, SSRIs, Rat, Pregnancy, Sexual behaviour, side effects in humans. These characteristics (se- Emotionality, Learning, Memory. lectivity, efficacy, lower side effects and simplici- ty of dosage) have contributed to fluoxetine’s clinical acceptance1. Fluoxetine in UK has been the principal SSRIs prescribed for depression2. The clinical efficacy of several SSRIs like sertra- Abbreviatons line, zimelidine, fluoxetine, fluvoxamine and paroxetine were compared with some classic tri- GD = Gestational day cyclic antidepressants whose efficacy or onset of PND = Postnatal day action have a different side effects potential. SS- CS = Conditioned stimulus RIs resulted unable to replace tricyclics antide- US = Unconditioned stimulus pressants but had a useful addition to various F5 = Fluoxetine 5 mg/Kg drugs currently used for the treatment of depres- Corresponding Author: Raffaele CAGIANO, MD; e-mail: [email protected] 137 R. Cagiano, P. Flace, I. Bera, L. Maries, G. Cioca, R. Sabatini, V. Benagiano, et al. sion3. SSRIs and tricyclics are frequently used by It was concluded that neonates, exposed to SS- women of reproductive age, since several major RIs during the last trimester of pregnancy, should psychiatric disorders could be present during this be closely followed-up for after birth withdrawal time period. While pregnant, a significant num- symptoms31; on the contrary, other clinical stud- ber of women may be taking SSRIs for major or ies focused on the use of SSRIs during the first minor depression and up to 10% of pregnant trimester of pregnancy seemed not to be associat- women fulfill diagnostic criteria with an even ed with measurable teratogenic effects in high percentage in developing postpartum de- humans32 and that, in utero exposure to antide- pressions4-6. In addition, mood disorders and anx- pressant drugs, does not affect global IQ, lan- iety disorders, usually present in women during guage development or behavioral development in their childbearing years, increase the potential preschool children33. need of an antidepressant therapy during preg- Due to a poor number of informations avail- nancy7. able from prospective studies providing changes Several studies, performed in socially disad- from decision based on non-prospective data, it vantaged populations, reported a relationship be- was strictly recommended monitoring and inter- tween an increased risk for obstetric complica- ventions for patients with identified risks (e.g., tions and maternal depression together with pre- poor weight gain)34. Therefore, a recent clinical term birth and/or small offsprings for their relat- study evidenced an increased risk of low birth ed gestational age8-18. Some recent reviews sug- weight, jaundice and respiratory distress in in- gest that fluoxetine, or SSRIs group, are actually fants born from mothers perinatally exposed to considered the first line of treatment of depres- SSRIs35. sion during pregnancy19-21. A large number of experimental studies have Due to a lower ability to be metabolized and to been reported on the animal exposure to fluoxe- a lower capacity of glomerular filtration rate, tine during pregnancy. One research demonstrat- psychotropic drugs quickly trespass the placenta ed a prolonged 30% down-regulation of and their fetal metabolites could result higher [3H]imipramine binding sites in the cerebral cor- than the level found into maternal circulation22. tex of rats exposed to fluoxetine during pregnan- Caused by the immaturity of the fetal blood- cy. Conversely, the 5-HT disruptions were not brain-barrier, an high level of psychotropic drugs seen in adult rats treated with fluoxetine suggest- could be also found in the fetal brain23. Blood ing that the rat developing brain is particularly samples in umbilical cord at delivery also result- sensitive to the antidepressants36. Fluoxetine, ad- ed to contain antidepressants and metabolites24. ministered in rats during pregnancy, induced a Moreover, fluoxetine resulted to easy cross the decrease of the body weight in both sexes at birth placenta with subsequent fetal distribution during and in 70 days old males. Moreover, it was also and after organogenesis with the highest concen- found a 35% reduction in hypothalamic 5- tration of the radiolabeled fluoxetine localized in HT2A/2C receptor density not fully evident until the fetal brain and thymus25. puberty. It was hypothesized that an hormonal In addition, clinical evaluation of exposed fe- change, related with the animal age, could be in- tuses to fluoxetine during the third trimester of volved in the expression of such effects; func- pregnancy (but not limited to), showed postnatal tional changes of the serotonergic system were complications including irritability, jitteriness, also seen: a significant (58%) reduction in the el- sleep disturbance, palpitations and premature de- evation of plasma adrenocorticotropic hormone 26 livery . A clinical study regarding the exposure was also found in response to a 5-HT2A/2C ago- during pregnancy demonstrated, in the newborn nist37. In addition, it was demonstrated that pre- exposed to fluoxetine during the last trimester, a natal exposure to fluoxetine produced in brain 5- slight delays in psychomotor development and in HT neurons and 5-HT transporters of male rat motor movement control27 with an associated offspring, region-specific and age-dependent higher rate of prematurity, a lower APGAR score, changes38,39. In vitro exposure studies to sertra- a low-birth weight, an admission to special care line, fluoxetine and amitriptyline on mouse em- nurseries (SCNs) and a “poor neonatal adapta- bryos, produced craniofacial malformations40. tion”28-30. Another clinical study, focused on the These data were also supported by a study on the safe use of SSRIs during the last trimester of role of serotonin during the mammalian craniofa- pregnancy, found a neonatal withdrawal syn- cial development41. In another study, it was also drome occurring after in utero exposure to SSRIs. found that the prenatal exposure to fluoxetine af- 138 Neurofunctional effects in rats prenatally exposed to fluoxetine fected birth weight and sex of rats also reducing Reproduction Data the duration of pregnancy42. Furthermore, an in- The body weights of dams (Vehicle group: 10 creased incidence of skin haematomas was found dams; F5 group: 11 dams; F10 group 11 dams) in pregnant mice exposed to fluoxetine from day were taken on day 0 and from 13 to 20 days of 7 of gestation up to delivery43. gestation. For each group were detected and On the basis of the above exposed clinical and analized the number of male and females/litter, experimental data, the aim of the present study is gestation length (days), dams giving birth (%), to investigate the cognitive functions, the emo- pregnancy length (days), dams weight gain (%), tional reactivity and the sexual performance of litter size at birth (n), postnatal mortality (%), adult rats prenatally exposed to fluoxetine (5, 10 male and female birth-weight/litter (g), pups mg/kg) during the last
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