151
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Forcano L, Santamaría J, Mackintosh N, Chamizo V. Single landmark learning in rats: Sex differences in a navigation task. LEARNING AND MOTIVATION 2009. [DOI: 10.1016/j.lmot.2008.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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152
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Abstract
Accumulating evidence suggests that the antecedents, consequences, and mechanisms of drug abuse and dependence are not identical in males and females and that gender may be an important variable in treatment and prevention. Although there has been a decline in smoking prevalence in developed countries, females are less successful in quitting. Tobacco use is accepted to be a form of addiction, which manifests sex differences. There is also evidence for sex differences in the central effects of nicotine in laboratory animals. Although social factors impact smoking substantially in humans, findings from nonhuman subjects in controlled experiments provide support that sex differences in nicotine/tobacco addiction have a biological basis. Differences in the pharmacokinetic properties of nicotine or the effect of gonadal hormones may underlie some but not all sex differences observed. Laboratory-based information is very important in developing treatment strategies. Literature findings suggest that including sex as a factor in nicotine/tobacco-related studies will improve our success rates in individually tailored smoking cessation programs.
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Affiliation(s)
- Sakire Pogun
- Ege University Center for Brain Research, Ege University, Bornova, Izmir, 35100, Turkey.
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153
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Gresack JE, Schafe GE, Orr PT, Frick KM. Sex differences in contextual fear conditioning are associated with differential ventral hippocampal extracellular signal-regulated kinase activation. Neuroscience 2009; 159:451-67. [PMID: 19171181 DOI: 10.1016/j.neuroscience.2009.01.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 12/12/2008] [Accepted: 01/07/2009] [Indexed: 10/21/2022]
Abstract
Although sex differences have been reported in hippocampal-dependent learning and memory, including contextual fear memories, the underlying molecular mechanisms contributing to such differences are not well understood. The present study examined the extent to which sex differences in contextual fear conditioning are related to differential activation of the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK), a protein kinase critically involved in memory formation. We first show that male rats exhibit more long-term retention of contextual fear conditioning than female rats. During a tone test, females spent more time freezing than males, although both sexes exhibited robust retention of auditory fear learning. Using Western blot analysis, we then show that phosphorylated ERK levels in ventral, but not dorsal, hippocampus are higher in males than females, relative to same-sex controls, 60 minutes after fear conditioning. Post-conditioning increases in ERK activation were observed in the amygdala in both males and females, suggesting a selective effect of sex on hippocampal ERK activation. Together, these findings suggest that differential activation of the ERK signal transduction pathway in male and female rats, particularly in the ventral hippocampus, is associated with sex differences in contextual fear.
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Affiliation(s)
- J E Gresack
- Department of Psychology, Yale University, PO Box 208205, New Haven, CT 06520, USA
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154
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Huttenlocher J, Levine S, Vevea J. Environmental Input and Cognitive Growth: A Study Using Time-Period Comparisons. Child Dev 2008. [DOI: 10.1111/j.1467-8624.1998.tb06158.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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155
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Abstract
Reduced androgen levels in aged men and women might be risk factors for age-related cognitive decline and Alzheimer's disease (AD). Ongoing clinical trials are designed to evaluate the potential benefit of estrogen in women and of testosterone in men. In this review, we discuss the potential beneficial effects of androgens and androgen receptors (ARs) in males and females. In addition, we discuss the hypothesis that AR interacts with apolipoprotein (apoE)4, encoded by epsilon4 and a risk factor for age-related cognitive decline and AD, and the potential consequences of this interaction.
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Affiliation(s)
- Jacob Raber
- Department of Behavioral Neuroscience, Division of Neuroscience, ONPRC, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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156
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Meyer-Bahlburg HFL, Dolezal C, Baker SW, New MI. Sexual orientation in women with classical or non-classical congenital adrenal hyperplasia as a function of degree of prenatal androgen excess. ARCHIVES OF SEXUAL BEHAVIOR 2008; 37:85-99. [PMID: 18157628 DOI: 10.1007/s10508-007-9265-1] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
46,XX individuals with classical congenital adrenal hyperplasia (CAH) due to deficiency of the enzyme, 21-hydroxylase, show variable degrees of masculinization of body and behavior due to excess adrenal androgen production. Increased bisexuality and homosexuality have also been reported. This article provides a review of existing reports of the latter and presents a new study aimed at replicating the previous findings with detailed assessments of sexual orientation on relatively large samples, and at extending the investigation to the mildest form, non-classical (NC) CAH. Also, this is the first study to relate sexual orientation to the specific molecular genotypes of CAH. In the present study, 40 salt-wasters (SW), 21 SV (simple-virilizing), 82 NC, and 24 non-CAH control women (sisters and female cousins of CAH women) were blindly administered the Sexual Behavior Assessment Schedule (SEBAS-A, 1983 ed.; H. F. L. Meyer-Bahlburg & A. A. Ehrhardt, Privately printed). Most women were heterosexual, but the rates of bisexual and homosexual orientation were increased above controls not only in women with classical CAH, but also in NC women, and correlated with the degree of prenatal androgenization. Classifying women by molecular genotypes did not further increase the correlation. Diverse aspects of sexual orientation were highly intercorrelated, and principal components analysis yielded one general factor. Bisexual/homosexual orientation was (modestly) correlated with global measures of masculinization of non-sexual behavior and predicted independently by the degree of both prenatal androgenization and masculinization of childhood behavior. We conclude that the findings support a sexual-differentiation perspective involving prenatal androgens on the development of sexual orientation.
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Affiliation(s)
- Heino F L Meyer-Bahlburg
- New York State Psychiatric Institute & Department of Psychiatry, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA.
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157
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Abstract
Female mice are more susceptible to apolipoprotein E (apoE4)-induced cognitive deficits than male mice. These deficits can be antagonized by stimulating androgen receptors (ARs). To determine the role of AR in the cognitive effects of apoE4, we backcrossed mutant mice with a naturally occurring defect in the AR [testicular feminization mutant (tfm)] onto the Apoe-/- background to eliminate mouse apoE gene resulting in non-functional AR, and crossed the tfm/Apoe-/- female mice with apoE4 transgenic male mice. We behaviorally compared Apoe-/-, apoE4, tfm, and tfm/apoE4 male mice. Apoe-/-, apoE4, and tfm mice showed hippocampus-dependent novel location recognition but tfm/apoE4 mice did not. In contrast, all groups showed hippocampus-independent novel object recognition. Hippocampus-dependent learning and memory were also assessed in the water maze. In the water maze probe trial following the second day of hidden platform training, Apoe-/- and apoE4 mice showed spatial memory retention, but tfm and tfm/ApoE4 mice did not. In the water maze, probe trial following the third day of hidden platform training, Apoe-/-, apoE4, and tfm/Apoe-/- mice showed spatial memory retention, but tfm mice did not. These data support an important role for AR in protecting against the detrimental effects of apoE4 on hippocampus-dependent learning and memory.
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Affiliation(s)
- Angela Rizk-Jackson
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97201, USA
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158
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Panzica GC, Viglietti-Panzica C, Mura E, Quinn MJ, Lavoie E, Palanza P, Ottinger MA. Effects of xenoestrogens on the differentiation of behaviorally-relevant neural circuits. Front Neuroendocrinol 2007; 28:179-200. [PMID: 17868795 DOI: 10.1016/j.yfrne.2007.07.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 06/11/2007] [Accepted: 07/12/2007] [Indexed: 11/18/2022]
Abstract
It has become increasingly clear that environmental chemicals have the capability of impacting endocrine function. Moreover, these endocrine disrupting chemicals (EDCs) have long term consequences on adult reproductive function, especially if exposure occurs during embryonic development thereby affecting sexual differentiation. Of the EDCs, most of the research has been conducted on the effects of estrogen active compounds. Although androgen active compounds are also present in the environment, much less information is available about their action. However, in the case of xenoestrogens, there is mounting evidence for long-term consequences of early exposure at a range of doses. In this review, we present data relative to two widely used animal models: the mouse and the Japanese quail. These two species long have been used to understand neural, neuroendocrine, and behavioral components of reproduction and are therefore optimal models to understand how these components are altered by precocious exposure to EDCs. In particular we discuss effects of bisphenol A and methoxychlor on the dopaminergic and noradrenergic systems in rodents and the impact of these alterations. In addition, the effects of embryonic exposure to diethylstilbestrol, genistein or ethylene,1,1-dichloro-2,2-bis(p-chlorophenyl) is reviewed relative to behavioral impairment and associated alterations in the sexually dimorphic parvocellular vasotocin system in quail. We point out how sexually dimorphic behaviors are particularly useful to verify adverse developmental consequences produced by chemicals with endocrine disrupting properties, by examining either reproductive or non-reproductive behaviors.
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159
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Bäckström T. Symptoms related to the menopause and sex steroid treatments. CIBA FOUNDATION SYMPOSIUM 2007; 191:171-80; discussion 180-6. [PMID: 8582196 DOI: 10.1002/9780470514757.ch10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In the menopause transition, ovarian steroid production is gradually inhibited and around 35% of women will seek medical help for postmenopausal symptoms. The hot flush is a characteristic manifestation occurring in about 70% of women; it is associated with oestrogen withdrawal and disappears with oestrogen-based hormone replacement therapy. The exact mechanism behind it is still unclear but is probably related to heat loss mechanisms. The flush often occurs in parallel to changes in skin temperature, blood flow, pulse rate and pulses of luteinizing hormone (LH). These are probably secondary to a disturbance in the thermoregulatory centre of the CNS, which is anatomically close to neurons containing gonadotropin-releasing hormone. Depression is no more frequent in the menopausal transition than at other times in life. After surgical menopause, however, oestrogen improves low mood over placebo. In women with premenstrual syndrome, an increased feeling of well-being is associated with the pre-ovulatory oestrogen peak. Progestogens are associated with negative mood changes during the menstrual cycle, oral contraception and postmenopausal replacement therapy. Certain progesterone metabolites are anaesthetic and have anti-epileptic and anxiolytic properties, effects which are mediated via the type A gamma-aminobutyric acid (GABAA) receptor. Oestrogen is associated with increased sensory perception, locomotory activity, limb coordination and balance: this may help explain the increased frequency of bone fractures in the early postmenopausal period. Oestrogen improves memory and performance in patients with mild Alzheimer's dementia and increases epileptic activity in patients with partial epilepsy. These effects can be related to amplifying effects of oestrogen on excitatory amino acids in the CNS.
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Affiliation(s)
- T Bäckström
- Department of Obstetrics and Gynecology, University Hospital, Umeå, Sweden
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160
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Gioiosa L, Fissore E, Ghirardelli G, Parmigiani S, Palanza P. Developmental exposure to low-dose estrogenic endocrine disruptors alters sex differences in exploration and emotional responses in mice. Horm Behav 2007; 52:307-16. [PMID: 17568585 DOI: 10.1016/j.yhbeh.2007.05.006] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2006] [Revised: 05/04/2007] [Accepted: 05/04/2007] [Indexed: 11/30/2022]
Abstract
Estrogenic endocrine disruptors (EEDs) are naturally occurring or man-made compounds present in the environment that are able to bind to estrogen receptors and interfere with normal cellular development in target organs and tissues. There is mounting evidence that EEDs can interfere with the processes of sexual differentiation of brain and behavior in different animal models. We investigated the effects of maternal exposure to EEDs, at concentrations within the range of human exposure and not patently teratogenic, on behavioral responses of male and female house mice (Mus musculus domesticus) before and after puberty. Pregnant dams were trained to spontaneously drink daily doses of corn oil with or without the estrogenic plastic derivative, bisphenol A (BPA 10 microg/kg), or the estrogenic insecticide methoxychlor (MXC 20 microg/kg) from gestation day 11 to postpartum day 8. Their male and female offspring were examined at different ages to examine several components of explorative and emotional behaviors in 3 experimental paradigms: a novelty test before puberty and, as adults, a free-exploratory open-field test and the elevated plus maze test. The main results are sex differences in control mice on a number of behavioral responses at both ages and in all experimental paradigms, while perinatal exposure to BPA or MXC decreased or eliminated such sex differences. The present findings are evidence of long-term consequences of developmental exposure to BPA and MXC on neurobehavioral development and suggest a differential effect of low-dose exposure to these estrogenic chemicals in males and females.
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Affiliation(s)
- Laura Gioiosa
- Dipartimento di Biologia Evolutiva e Funzionale, Università di Parma, Viale Usberti 11A, 43100 Parma, Italy
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161
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Drea CM. Sex and seasonal differences in aggression and steroid secretion in Lemur catta: are socially dominant females hormonally 'masculinized'? Horm Behav 2007; 51:555-67. [PMID: 17382329 DOI: 10.1016/j.yhbeh.2007.02.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 02/12/2007] [Accepted: 02/14/2007] [Indexed: 11/20/2022]
Abstract
Female social dominance characterizes many strepsirrhine primates endemic to Madagascar, but currently there is no comprehensive explanation for how or why female lemurs routinely dominate males. Reconstructing the evolutionary pressures that may have shaped female dominance depends on better understanding the mechanism of inheritance, variation in trait expression, and correlating variables. Indeed, relative to males, many female lemurs also display delayed puberty, size monomorphism, and 'masculinized' external genitalia. As in the spotted hyena (Crocuta crocuta), a species characterized by extreme masculinization of the female, this array of traits focuses attention on the role of androgens in female development. Consequently, I examined endocrine profiles and social interaction in the ringtailed lemur (Lemur catta) to search for a potential source of circulating androgen in adult females and an endocrine correlate of female dominance or its proxy, aggression. I measured serum androstenedione (A(4)), testosterone (T), and estradiol (E(2)) in reproductively intact, adult lemurs (10 females; 12 males) over four annual cycles. Whereas T concentrations in males far exceeded those in females, A(4) concentrations were only slightly greater in males than in females. In both sexes, A(4) and T were positively correlated, implicating the Delta(4)-biosynthetic pathway. Moreover, seasonal changes in reproductive function in both sexes coincided with seasonal changes in behavior, with A(4) and T in males versus A(4) and E(2) in females increasing during periods marked by heightened aggression. Therefore, A(4) and/or E(2) may be potentially important steroidal sources in female lemurs that could modulate aggression and underlie a suite of masculinized features.
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Affiliation(s)
- Christine M Drea
- Department of Biological Anthropology and Anatomy, Duke University, 08 Biological Sciences Bldg., Box 90383, Durham, NC 27708-0383, USA.
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162
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Wilson CA, Davies DC. The control of sexual differentiation of the reproductive system and brain. Reproduction 2007; 133:331-59. [PMID: 17307903 DOI: 10.1530/rep-06-0078] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This review summarizes current knowledge of the genetic and hormonal control of sexual differentiation of the reproductive system, brain and brain function. While the chromosomal regulation of sexual differentiation has been understood for over 60 years, the genes involved and their actions on the reproductive system and brain are still under investigation. In 1990, the predicted testicular determining factor was shown to be theSRYgene. However, this discovery has not been followed up by elucidation of the actions of SRY, which may either stimulate a cascade of downstream genes, or inhibit a suppressor gene. The number of other genes known to be involved in sexual differentiation is increasing and the way in which they may interact is discussed. The hormonal control of sexual differentiation is well-established in rodents, in which prenatal androgens masculinize the reproductive tract and perinatal oestradiol (derived from testosterone) masculinizes the brain. In humans, genetic mutations have revealed that it is probably prenatal testosterone that masculinizes both the reproductive system and the brain. Sexual differentiation of brain structures and the way in which steroids induce this differentiation, is an active research area. The multiplicity of steroid actions, which may be specific to individual cell types, demonstrates how a single hormonal regulator, e.g. oestradiol, can exert different and even opposite actions at different sites. This complexity is enhanced by the involvement of neurotransmitters as mediators of steroid hormone actions. In view of current environmental concerns, a brief summary of the effects of endocrine disruptors on sexual differentiation is presented.
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Affiliation(s)
- C A Wilson
- Basic Medical Sciences, Clinical Developmental Sciences, St George's, University of London, Cranmer Terrace, Tooting, London SW17 0RE, UK.
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163
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Craft RM, Clark JL, Hart SP, Pinckney MK. Sex differences in locomotor effects of morphine in the rat. Pharmacol Biochem Behav 2007; 85:850-8. [PMID: 17217999 PMCID: PMC1868667 DOI: 10.1016/j.pbb.2006.11.022] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 11/15/2006] [Accepted: 11/28/2006] [Indexed: 12/25/2022]
Abstract
Sex differences in reinforcing, analgesic and other effects of opioids have been demonstrated; however, the extent to which sex differences in motoric effects of opioids contribute to apparent sex differences in their primary effects is not known. The goal of this study was to compare the effects of the prototypic mu opioid agonist morphine on locomotor activity in male vs. female rats. Saline or morphine (1-10 mg/kg) was administered s.c. to adult Sprague-Dawley rats, which were placed into a photobeam apparatus for 3-5 h to measure activity. Modulation of morphine's effects by gonadal hormones and by handling (either during the test session or for 4 days before the test session) were examined. Morphine initially suppressed and later increased locomotor activity in both sexes relative to their saline-injected controls, but males were more sensitive than females to the initial locomotor suppressant effect of morphine. Intermittent, brief handling during the 3-h test session blunted morphine-induced locomotor activation in both sexes. Females in proestrus were the most sensitive to morphine's locomotor-stimulant effect, with females in estrus showing the least response to morphine. Gonadectomized (GDX) males with or without testosterone were equally sensitive to morphine's effects, whereas GDX females treated with estradiol showed a blunted response to morphine's effects, similar to intact females in estrus. Brief handling on each of 4 consecutive days pre-test attenuated morphine's locomotor suppressant effect in males but had no effect in females, thereby eliminating the sex difference. These data suggest that sex differences in morphine's effects on locomotor activity can be attributed to gonadal hormones in females, and to differential stress-induced modulation of morphine's effects in males vs. females.
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Affiliation(s)
- Rebecca M Craft
- Department of Psychology, Washington State University, Pullman, WA 99164-4820, USA.
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164
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van Meer P, Acevedo S, Raber J. Impairments in spatial memory retention of GFAP-apoE4 female mice. Behav Brain Res 2006; 176:372-5. [PMID: 17126420 PMCID: PMC1950679 DOI: 10.1016/j.bbr.2006.10.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 10/23/2006] [Accepted: 10/24/2006] [Indexed: 10/23/2022]
Abstract
The human apolipoprotein E isoforms, apoE2, apoE3, and apoE4, have differential effects on brain function. Compared to apoE3, apoE4 increases the risk of age-related cognitive decline in humans and female mice expressing apoE in neurons. Here, we show impaired spatial memory retention in female mice expressing apoE4 in astrocytes compared to those expressing apoE3 in astrocytes or lacking apoE. Thus, apoE4 impairs cognition whether expressed in neurons or astrocytes.
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Affiliation(s)
- Peter van Meer
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97239
| | - Summer Acevedo
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97239
| | - Jacob Raber
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon 97239
- Department of Neurology, Oregon Health & Science University, Portland, Oregon 97239
- Division of Neuroscience, ONPRC, Oregon Health & Science University, Portland, Oregon 97239
- Address for correspondence: Jacob Raber, Departments of Behavioral Neuroscience and Neurology, L470, Oregon Health and Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR97201., Office: (503) 494-1524, Lab: (503) 494-1431, Fax: (503) 494-6877, e-mail:
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165
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Eklund MB, Arborelius L. Twice daily long maternal separations in Wistar rats decreases anxiety-like behaviour in females but does not affect males. Behav Brain Res 2006; 172:278-85. [PMID: 16780968 DOI: 10.1016/j.bbr.2006.05.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 05/11/2006] [Accepted: 05/12/2006] [Indexed: 11/24/2022]
Abstract
Prolonged daily separations of rat pups from their mother have been reported to increase anxiety-like behaviour in adult offspring. However, there are an increasing number of studies not showing this. It has been proposed that the effect of long maternal separation (LMS) is partly due to the disruption of maternal care caused by the separations. The aim of the present study was to investigate whether increasing the number of daily separations would produce more robust effects in the adult offspring on anxiety-like behaviour in the defensive withdrawal test, and on spontaneous motor activity. Since previous studies of LMS have revealed sex differences in behaviour, we included both males and females. In our separation paradigm we subjected rat pups to either two daily 3h maternal separations during the first 2 weeks postpartum (LMS), two daily 15 min maternal separations (brief maternal separations, BMS) during the same time period to control for the effects of handling, or to normal husbandry conditions. As adults we found no effects of this LMS paradigm in male rats, although BMS males showed a tendency toward decreased anxiety-like behaviour. In contrast, LMS females showed a decrease in anxiety-like behaviour. We also found significant sex differences that were most prominent in the LMS group, indicating that females are more sensitive to our maternal separation paradigm. The present study suggests that increasing the number of maternal separations does not increase anxiety-like behaviour in neither male nor female Wistar rats.
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Affiliation(s)
- Malin B Eklund
- Department of Physiology and Pharmacology, Section for Behavioural Neuropharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
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166
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Abstract
It is usually assumed that stressful life events interfere with our ability to acquire new information. However, many studies suggest that stressful experience can enhance processes involved in learning. The types of learning that are enhanced after stressful experiences include classical fear and eyeblink conditioning, as well as processes related to learning about threatening stimuli. Stressful life experiences do seem to interfere with processes involved in memory, often expressed as deficits in the retention or retrieval of information that was acquired prior to and was unrelated to the stressful experience. The trends are limited, as are their implications, because most studies examine adult males, yet the effects of stress on learning processes are influenced by age and sex differences. With respect to mechanisms and anatomical substrates, the effects of stress on learning are usually dependent on the action of stress hormones in combination with neuronal activities within the hippocampus, amygdala, the bed nucleus of the stria terminalis, and the prefrontal cortex.
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Affiliation(s)
- Tracey J Shors
- Department of Psychology, Center for Collaborative Neuroscience, Rutgers University, Piscataway, New Jersey 08854, USA.
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167
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Pfankuch T, Rizk A, Olsen R, Poage C, Raber J. Role of circulating androgen levels in effects of apoE4 on cognitive function. Brain Res 2005; 1053:88-96. [PMID: 16054121 DOI: 10.1016/j.brainres.2005.06.028] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 06/08/2005] [Accepted: 06/10/2005] [Indexed: 11/19/2022]
Abstract
Compared with apoE2 and E3, apoE4 increases the risk of cognitive impairments and of developing Alzheimer's disease (AD). ApoE4 interacts with female sex, further increasing AD risk. Previously, we showed that female Apoe-/- mice are more susceptible to apoE4-induced cognitive deficits than male mice. Androgens protect against these deficits and apoE4 male mice are more sensitive to acute blockade of androgen receptors than apoE3 male mice. To determine the chronic effects of reduced circulating androgen levels on susceptibility to the effects of apoE4 on cognitive function in males, we castrated and sham-castrated apoE4, apoE3, and Apoe-/- male mice and behaviorally compared them 3 months later. Castration impaired novel location recognition in apoE4, but not apoE3 or Apoe-/-, mice. In contrast, castration impaired novel object recognition and spatial memory retention in the water maze in Apoe-/-, but not apoE3 or apoE4, mice. On the contrary, castrated, but not sham-castrated, apoE4 mice showed improved acquisition over the first two hidden platform sessions and spatial memory retention in the first probe trial. While apoE3 and Apoe-/- mice increased their exploratory times with the objects in the trial with the novel object, apoE4 mice did not. ApoE4 mice required more trials than apoE3 or Apoe-/- mice to reach criterion during passive avoidance training, but castration did not modulate passive avoidance learning or memory. Thus, androgens have differential roles in object recognition and spatial learning and memory in the water maze, depending on whether or not apoE4 is present.
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Affiliation(s)
- Timothy Pfankuch
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR 97239, USA
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168
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Rose SA, Feldman JF, Jankowski JJ, Van Rossem R. Prenatal hormones and postnatal socialization by parents as determinants of male-typical toy play in girls with congenital adrenal hyperplasia. Child Dev 2005; 76:1172-84. [PMID: 16274433 DOI: 10.1111/j.1467-8624.2005.00843.x] [Citation(s) in RCA: 199] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Toy choices of 3- to 10-year-old children with congenital adrenal hyperplasia (CAH) and of their unaffected siblings were assessed. Also assessed was parental encouragement of sex-typed toy play. Girls with CAH displayed more male-typical toy choices than did their unaffected sisters, whereas boys with and without CAH did not differ. Mothers and fathers encouraged sex-typical toy play in children with and without CAH. However, girls with CAH received more positive feedback for play with girls' toys than did unaffected girls. Data show that increased male-typical toy play by girls with CAH cannot be explained by parental encouragement of male-typical toy play. Although parents encourage sex-appropriate behavior, their encouragement appears to be insufficient to override the interest of girls with CAH in cross-sexed toys.
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Affiliation(s)
- Susan A Rose
- Department of Pediatrics, Albert Einstein College of Medicine/Children's Hospital at Montefiore, Bronx, NY 10461, USA.
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169
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Rizk A, Robertson J, Raber J. Behavioral performance of tfm mice supports the beneficial role of androgen receptors in spatial learning and memory. Brain Res 2005; 1034:132-8. [PMID: 15713264 DOI: 10.1016/j.brainres.2004.12.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/08/2004] [Indexed: 10/25/2022]
Abstract
In adulthood, androgens and androgen receptors might contribute to the sexually dimorphic performance in spatial learning and memory, but their roles seem complex. To study the potential role of androgen receptors in spatial learning and memory, we tested adult 6-8-month-old mutant mice with a naturally occurring defect in the androgen receptor gene (testicular feminization mutant or tfm) and C57Bl/6J wild-type mice. Because the trait is X-linked, only tfm males are completely androgen insensitive while female tfm mice are heterozygous, carrying one wild-type and one tfm copy of the androgen receptor. Here we show that female tfm carrier mice outperform tfm male mice in the water maze, while there are no gender differences in water maze performance in wild-type mice. In tfm mice, there were no gender differences in measures of anxiety in the open field or plus maze or sensorimotor function, indicating that potential differences in these measures did not contribute to the differences observed in the water maze. There were no differences in tfm and wild-type female and male mice in emotional learning and memory in the passive avoidance test. These findings support a beneficial role for androgen receptors in spatial learning and memory.
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Affiliation(s)
- Angela Rizk
- Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR 97239, USA
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170
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Faruzzi AN, Solomon MB, Demas GE, Huhman KL. Gonadal hormones modulate the display of submissive behavior in socially defeated female Syrian hamsters. Horm Behav 2005; 47:569-75. [PMID: 15811359 DOI: 10.1016/j.yhbeh.2004.11.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Revised: 11/23/2004] [Accepted: 11/24/2004] [Indexed: 10/25/2022]
Abstract
There are striking differences in the behavioral response to social defeat between male and female Syrian hamsters. Whereas males exhibit a prolonged behavioral response to defeat (i.e., conditioned defeat), many females remain aggressive or show only a transient submissive response following defeat. The current study tested the hypothesis that sex steroids underlie this differential behavioral responsivity to social defeat. Female hamsters were ovariectomized and implanted with Silastic capsules containing estradiol (E(2)), testosterone (T), progesterone (P), dihydrotestosterone (DHT), or a blank capsule (no hormone replacement). After a 3-week recovery period, each subject was placed inside the home cage of a larger, more aggressive female for four 5-min defeat trials. The following day, each animal was tested for conditioned defeat by testing it in its own home cage in the presence of a smaller, non-aggressive intruder. Submissive, aggressive, social, and nonsocial behaviors were subsequently scored. Hamsters receiving E(2) or T displayed significantly lower levels of submissive behavior than did animals receiving P, DHT, or no hormone replacement. There were no significant differences in aggressive behavior among groups. These data suggest that gonadal hormones can influence submissive behavior in female hamsters. Collectively, these results suggest that the sex differences observed in conditioned defeat may, in part, be explained by sex differences in circulating gonadal hormones.
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Affiliation(s)
- Alicia N Faruzzi
- Department of Psychology, Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA 30303, USA
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171
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Harrod SB, Mactutus CF, Bennett K, Hasselrot U, Wu G, Welch M, Booze RM. Sex differences and repeated intravenous nicotine: behavioral sensitization and dopamine receptors. Pharmacol Biochem Behav 2005; 78:581-92. [PMID: 15251267 DOI: 10.1016/j.pbb.2004.04.026] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Revised: 04/14/2004] [Accepted: 04/28/2004] [Indexed: 11/21/2022]
Abstract
The present study examined the sex-dependent expression of behavioral sensitization as well as changes of dopamine (DA) transporters and D1, D2, and D3 receptors following repeated intravenous nicotine administration. Male and female Sprague-Dawley rats were implanted with indwelling jugular catheters, equipped with subcutaneous intravenous injection ports. Rats were habituated to activity chambers for 3 days and were subsequently administered 15-s bolus injections of intravenous nicotine (50 microg/kg/ml) 1/day for 21 days. Animals were placed in activity chambers for 60 min immediately after the 1st and 21st nicotine injection. Observational time sampling was also performed. Brains were subsequently removed and frozen for autoradiographic DA transporter/DA receptor analysis on the afternoon females were in proestrus. With one exception, no robust sex differences were observed for locomotor activity or any rearing measures either during baseline or after initial nicotine injection. Females exhibited markedly more behavioral sensitization of locomotor activity, rearing, duration of rearing, and incidence of observed rearing. There were no sex differences in the number of D1 or D2 receptors. Females exhibited an increased number of DA transporters and decreased D3 receptors in the NAcc, relative to males. Multiple regression analyses suggest that D3 receptors and DA transporters in various striatal and NAcc subregions differentially predicted nicotine-induced behaviors for males and females. Collectively, these findings demonstrate that repeated intravenous nicotine produces sex differences in the expression of behavioral sensitization, and suggest that nicotine-induced changes of DA transporters and D3 receptors are partly responsible for increased behavioral sensitization in female rats.
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Affiliation(s)
- Steven B Harrod
- Department of Psychology, University of South Carolina, 1512 Pendleton Street, Columbia, SC 29208, USA.
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172
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Barreto-Estrada JL, Barreto J, Fortis-Santiago Y, Rivera-Ramos I, Fortis-Santiago A, Jorge JC. Modulation of affect after chronic exposure to the anabolic steroid 17alpha-methyltestosterone in adult mice. Behav Neurosci 2005; 118:1071-9. [PMID: 15506889 DOI: 10.1037/0735-7044.118.5.1071] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A battery of behavioral tasks in C57BL/6J mice was used to assess changes in affective components of behavior after systemic exposure to the anabolic-androgenic steroid (AAS) 17alpha-methyltestosterone (7.5 mg/kg). Gonadal weight in both sexes was reduced after 16 days of AAS exposure. Changes in discrete components of social behaviors were observed. No changes were recorded in the elevated plus-maze, the light-dark transition, and defensive behavior tests on exposure to 17alpha-methyltestosterone. When compared with controls, AAS-exposed females received a greater number of shocks, and AAS-exposed males displayed a shorter recovery time to consume water after a negative reinforcer in the modified Vogel conflict test. Results show that systemic exposure to a single AAS modified social behaviors, whereas minimal effects on anxiety-related behaviors were observed according to sex.
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173
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Kudo K, Qiao CX, Kanba S, Arita J. A selective increase in phosphorylation of cyclic AMP response element-binding protein in hippocampal CA1 region of male, but not female, rats following contextual fear and passive avoidance conditioning. Brain Res 2005; 1024:233-43. [PMID: 15451386 DOI: 10.1016/j.brainres.2004.08.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2004] [Indexed: 11/30/2022]
Abstract
Cyclic AMP response element-binding protein (CREB), a transcription factor on which multiple signal transduction pathways converge, has been implicated in long-term memory. We examined whether the sex difference in the performance of contextual fear or passive avoidance conditioning is associated with a change in the activation of CREB in the hippocampus, a neural structure important for long-term memory. The activation of CREB in different subregions within the hippocampus in male and female rats was determined immunohistochemically with an antibody that specifically recognizes the phosphorylated form of CREB (pCREB). With respect to the freezing time in contextual fear conditioning and the step-through latency in passive avoidance conditioning, male rats exhibited better performance than female rats. Phosphorylation of CREB (% pCREB) as revealed by the ratio of the pCREB-immunoreactive (pCREB-ir) cell number to the CREB-immunoreactive cell number was increased in the CA1 region, but not in CA3, CA4, or in the dentate gyrus following training for both types of conditioning in males. In females, such an increase in % pCREB was not found in any hippocampal subregion at any time after conditioning or by increasing the intensity of foot shock. Orchidectomy in males did not alter either the performance of contextual conditioning or conditioning-induced CREB phosphorylation in CA1. The close relationship between behavioral performance and CREB phosphorylation in the CA1 region suggests that hippocampal CREB is involved in the sex difference in some forms of learning and memory.
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Affiliation(s)
- Koutarou Kudo
- Department of Neuropsychiatry, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Tamaho, Yamanashi 409-3898, Japan
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174
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Jonasson Z. Meta-analysis of sex differences in rodent models of learning and memory: a review of behavioral and biological data. Neurosci Biobehav Rev 2005; 28:811-25. [PMID: 15642623 DOI: 10.1016/j.neubiorev.2004.10.006] [Citation(s) in RCA: 377] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2003] [Revised: 10/03/2004] [Accepted: 10/08/2004] [Indexed: 10/25/2022]
Abstract
The existence of sex differences in the standard rat and mouse models of learning and memory is a controversial and contested topic in the literature. The present meta-analysis of radial maze and water maze experiments was conducted to assess the reliablility and magnitude of sex effects in the standard rodent models of learning and memory. Data were culled from published and unpublished sources. Findings indicate large reliable male advantages for rats in radial maze and water maze protocols. Significant strain differences were also identified. In each paradigm, protocol variations were associated with differential sex effects. For the water maze, smaller male advantages were associated with pretraining regimens and for the radial maze, larger significant male advantages were observed in protocols that included unbaited arms (combined reference and working memory protocols). Mouse studies exhibited a different pattern of sex effects; small female advantages were evident in the water maze, but small male advantages were evident in the radial maze. Together these findings establish the reliability of male advantages in spatial working and reference memory for rats across strains, protocols, ages and rearing environments. The findings also support an important species dichotomy between rats and mice that should be considered when transitioning from rat to mouse models. In light of these results, the biological evidence supporting theoretical explanations of sex differences is reviewed and evaluated.
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Affiliation(s)
- Zachariah Jonasson
- Neuroscience Program, Department of Psychology, Harvard University, Cambridge, MA 02138, USA.
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175
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Mussi P, Ciana P, Raviscioni M, Villa R, Regondi S, Agradi E, Maggi A, Di Lorenzo D. Activation of brain estrogen receptors in mice lactating from mothers exposed to DDT. Brain Res Bull 2004; 65:241-7. [PMID: 15811587 DOI: 10.1016/j.brainresbull.2004.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The insecticide dichlorodiphenyltrichloroethane (DDT) interferes with physiological endocrine processes modulating estrogens receptor activity. Most of the data describing the DDT mechanism of action have been collected in vitro or in reproductive tissues in vivo. Here we use a new transgenic mouse model to investigate the DDT effects on estrogens receptor activation in vivo in non-reproductive tissues. In particular, we demonstrate that DDT is able to activate estrogen receptors in the brain and the liver of adult mice after acute administration, and it is active in lactating mice when accumulated in the mother's milk. Furthermore, we demonstrate that the acute administration of DDT activates estrogen receptors with a different kinetics with respect to 17beta-estradiol. Experiments with a breast cancer cell line engineered to express luciferase under the transcriptional control of activated estrogen receptors reveal that the microsomal metabolization of DDT is required for its full activity on estrogen receptors. Taken together these data lead to hypothesize that the delayed DDT time course on estrogen receptor activation in vivo might be due to a necessary step of metabolism of the compound.
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Affiliation(s)
- P Mussi
- Department of Pharmacological Sciences, Center of Excellence on Neurodegenerative Diseases, University of Milan, Via Balzaretti 9, 20133 Milan, Italy
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176
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Laviola G, Gioiosa L, Adriani W, Palanza P. D-amphetamine-related reinforcing effects are reduced in mice exposed prenatally to estrogenic endocrine disruptors. Brain Res Bull 2004; 65:235-40. [PMID: 15811586 DOI: 10.1016/j.brainresbull.2004.11.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Estrogenic endocrine disruptors are hormonally active compounds that can bind to estradiol receptors. Central dopamine pathways have been reported to be affected by early developmental exposure to estrogenic endocrine disruptors. In the present study, pregnant female CD-1 mice were allowed to drink spontaneously either oil or environmentally relevant low doses of two estrogenic compounds, methoxychlor (20 microg/kg) or bisphenol-A (10 microg/kg) during gestation days 11-18. Their adult offspring were assessed for conditioned place preference produced by D-amphetamine (0, 1 or 2 mg/kg). Interestingly, prenatal treatment effects were sex-dependent and no changes in conditioned place preference emerged for the male offspring. Conversely, a clear-cut profile of D-amphetamine-induced conditioned place preference was only shown by oil-exposed females, whereas exposure to bisphenol-A or methoxychlor resulted in little or no place conditioning. Locomotor effects of acute d-amphetamine were not affected by prenatal exposure to bisphenol-A or methoxychlor. As a whole, prenatal exposure to estrogenic endocrine disruptors affected some steps in the organization of the brain dopaminergic systems in the female offspring, thus leading to long-term alterations in neurobehavioral function. These data confirm that exposure to weak environmental estrogens in the period of brain sexual differentiation can influence adult behavior.
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Affiliation(s)
- Giovanni Laviola
- Section of Behavioral Neuroscience, Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Viale Regina Elena, 299 I-00161 Roma, Italy.
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177
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O'Shea M, Singh ME, McGregor IS, Mallet PE. Chronic cannabinoid exposure produces lasting memory impairment and increased anxiety in adolescent but not adult rats. J Psychopharmacol 2004; 18:502-8. [PMID: 15582916 DOI: 10.1177/026988110401800407] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Although many studies have examined the acute behavioural effects of cannabinoids in rodents, few have examined the lasting effects of cannabinoids at different developmental ages. This study compared lasting effects of cannabinoid exposure occurring in adolescence to that occurring in early adulthood. Forty, 30-day old (adolescent) and 18, 56-day old (adult) female albino Wistar rats were injected with vehicle or incremental doses of the cannabinoid receptor agonist (-)-cis-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-trans-4-(3-hydroxypropyl) cyclohexanol (CP 55,940) once per day for 21 consecutive days (150, 200 and 300 microg/kg i.p. for 3, 8 and 10 days, respectively). Following a 21-day drug-free period, working memory was assessed using an object recognition task. Locomotor activity was also measured in the object recognition apparatus via a ceiling-mounted passive infrared sensor. Three days later, anxiety was assessed using a social interaction test. In the object recognition task, significantly poorer working memory was observed in the adolescent but not adult CP 55,940-treated rats. Adolescent, but not adult CP 55,940-treated rats, also exhibited a significant decrease in social interaction with a novel conspecific. These results suggest that chronic exposure to a cannabinoid receptor agonist well after the immediate postnatal period, but before reaching sexual maturity, can lead to increased anxiety and a lasting impairment of working memory.
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Affiliation(s)
- Melanie O'Shea
- School of Psychology, University of New England, Armidale, New South Wales 2351, Australia
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178
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Mathews GA, Fane BA, Pasterski VL, Conway GS, Brook C, Hines M. Androgenic influences on neural asymmetry: Handedness and language lateralization in individuals with congenital adrenal hyperplasia. Psychoneuroendocrinology 2004; 29:810-22. [PMID: 15110930 DOI: 10.1016/s0306-4530(03)00145-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2002] [Accepted: 07/07/2003] [Indexed: 11/23/2022]
Abstract
This study tested the hypothesis that prenatal androgen levels influence hand preferences and language lateralization, two manifestations of neural asymmetry. Participants were individuals with congenital adrenal hyperplasia (CAH, a genetic disorder that results in excess adrenal androgen production beginning prenatally) (40 females; 29 males) and their unaffected relatives (29 females; 30 males) who ranged in age from 12-45 years. The Edinburgh-Crovitz Inventory and the performance of five simple tasks (the Handedness Activities Test) were the measures of hand preferences, and a dichotic listening task composed of consonant-vowel nonsense syllables was the measure of language lateralization. No sex differences were observed among relative controls in hand preferences or language lateralization. Male participants with CAH were less consistently right-handed for writing than unaffected male relatives, when those who had been forced to switch writing hands from left to right were considered with left-handers as being not consistently right-handed. There were no other significant differences between individuals with CAH and unaffected relatives. These results do not support the hypothesis that prenatal androgens influence language lateralization, nor do they support the Geschwind-Behan-Galaburda model that posits a key role for testosterone in the development of cognitive problems in males, secondary to changes in hemispheric development and cognitive lateralization. Hormonal influences on handedness, although not always consistent, may be more likely. However, given that sex differences in both language lateralization and handedness are small, it is possible that limited sample size precludes the detection of consistent group differences.
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179
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Wilson MA, Burghardt PR, Ford KA, Wilkinson MB, Primeaux SD. Anxiolytic effects of diazepam and ethanol in two behavioral models: comparison of males and females. Pharmacol Biochem Behav 2004; 78:445-58. [PMID: 15251253 DOI: 10.1016/j.pbb.2004.04.017] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Revised: 04/14/2004] [Accepted: 04/19/2004] [Indexed: 11/21/2022]
Abstract
The present study compared the anxiolytic effects of the benzodiazepine agonist diazepam and ethanol in adult male and female rats. Varying doses of diazepam (1-3 mg/kg) or ethanol (0.5-2.0 g/kg) were tested using both the elevated plus maze and defensive prod-burying models. Two time points following ethanol administration (10 and 30 min) were tested in the plus maze. Sex differences were seen in some anxiety-related behaviors, with females showing greater open arm time and reduced burying behavior than males. Although this suggests females displayed less anxiety-like behavior than males, the differences in the plus maze were not observed in all testing situations. Both diazepam and ethanol dose-dependently increased open arm times in the plus maze and reduced burying behavior in the defensive prod-burying task. The parallel nature of the dose-response curves suggests that both diazepam and ethanol have similar anxiolytic effects in males and females. No sex differences were seen in the brain levels of diazepam-like activity or blood alcohol levels with these treatments. A greater corticosterone response was observed in females than males with these two behavioral tests, but neither diazepam nor ethanol decreased this response. These results suggest a dissociation between the anxiety-reducing influences of these compounds and the changes in stress-related endocrine responses.
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Affiliation(s)
- Marlene A Wilson
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Building 1, D26 Columbia, SC 29208, USA.
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180
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Social Modulation of Androgens in Vertebrates: Mechanisms and Function. ADVANCES IN THE STUDY OF BEHAVIOR 2004. [DOI: 10.1016/s0065-3454(04)34005-2] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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181
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Kalynchuk LE, Gregus A, Boudreau D, Perrot-Sinal TS. Corticosterone Increases Depression-Like Behavior, With Some Effects on Predator Odor-Induced Defensive Behavior, in Male and Female Rats. Behav Neurosci 2004; 118:1365-77. [PMID: 15598145 DOI: 10.1037/0735-7044.118.6.1365] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This experiment examined the effect of repeated corticosterone injections on anxiety and depression-like behavior in male and female rats. Rats received either corticosterone or vehicle injections for 21 consecutive days prior to behavioral testing in the forced swim, open-field, and predator odor tests. The corticosterone injections significantly increased depression-like behavior in the forced swim test in both male and female rats but had no significant effect on anxiety in the open-field test. In the predator odor test, the corticosterone injections significantly increased a subset of defensive behaviors in the male rats. These results suggest that repeated exposure to corticosterone increases depression-like behavior, with some effects on anxiety, and that male rats may be more affected than female rats by this manipulation.
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Affiliation(s)
- Lisa E Kalynchuk
- Department of Psychology, Dalhousie University, Halifax, Nova Scotia, Canada.
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182
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Morley-Fletcher S, Palanza P, Parolaro D, Viganò D, Laviola G. Intrauterine position has long-term influence on brain mu-opioid receptor density and behaviour in mice. Psychoneuroendocrinology 2003; 28:386-400. [PMID: 12573304 DOI: 10.1016/s0306-4530(02)00030-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In multiparous rodents, a naturally occurring variation in degree of exposure to sex steroids during the prenatal phase of sexual differentiation derives from the in-utero proximity to opposite sex foetuses. So far, the studies on intrauterine position (IUP) phenomenon have mostly focused on traits relating to reproduction and behaviour, while its influence on neurochemical substrates and pharmacological response has been largely unexplored. We investigated possible variations in the function and the profile of expression of the mu-opioid receptor system in three groups of adult mice from known IUP: 2M mice (located between two males), 0M (between two females), and 1M (between a male and a female). Autoradiographic study revealed in female mice that proximity to at least a male in utero (1M and 2M position) resulted associated at adulthood with an increased density of midbrain mu-opioid receptors. Behavioural observations were conducted following injection with the specific mu-opioid agonist Fentanyl (at 0, 0.01 or 0.05 mg/kg IP). A drug-conditioned place preference test confirmed that 1M and 2M subjects were also more sensitive to the rewarding effects of the drug, since mice spent significantly more time in the drug-paired compartment than 0M subjects. In a hot-plate test, 2M subjects showed levels of drug-induced analgesia that were much higher than other IUP groups. No reliable differences were observed between the IUP groups for locomotor activity upon drug treatment. Overall, these data indicate for the first time that the organisation of the mu-opioid receptor system in the brain, as well as a differential vulnerability to abuse of opiate drugs can be modulated by epigenetic variables such as the prenatal in utero contiguity to male foetuses.
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Affiliation(s)
- Sara Morley-Fletcher
- Section of Behavioural Pathophysiology, Labor. F.O.S., Istituto Superiore di Sanità, Viale Regina Elena, 299 00161 Rome, Italy
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183
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Kelly PH, Bondolfi L, Hunziker D, Schlecht HP, Carver K, Maguire E, Abramowski D, Wiederhold KH, Sturchler-Pierrat C, Jucker M, Bergmann R, Staufenbiel M, Sommer B. Progressive age-related impairment of cognitive behavior in APP23 transgenic mice. Neurobiol Aging 2003; 24:365-78. [PMID: 12498971 DOI: 10.1016/s0197-4580(02)00098-2] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Transgenic APP23 mice expressing human APP(751) with the K670N/M671L mutation, were compared at ages 3, 18 or 25 months to non-transgenic littermates in passive avoidance and in a small and large Morris maze. The task in the smaller pool habituated their flight response to the platform. Impairments in passive avoidance and small pool performance in APP23 mice were clearly age-related. In the larger Morris maze APP23 mice at all ages were impaired in latency and distance swum before finding the platform. Identical performance of 18-month APP23 and controls in a visible platform condition indicates that the Morris maze performance deficit was not due to sensory, motor or motivational alterations. At age 3 months both groups initially unexpectedly avoided the visible platform, suggesting that in young mice neophobia may contribute significantly to performance in cognitive tests. In conclusion, APP23 mice exhibit both early behavioral impairment in the large Morris maze as well as impairments in passive avoidance and small pool performance that are marked only in old age.
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Affiliation(s)
- P H Kelly
- NS Research, Novartis Pharma A.G. Ltd., CH-4002 Basel, Switzerland.
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184
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Sandberg DE, Vena JE, Weiner J, Beehler GP, Swanson M, Meyer-Bahlburg HFL. Hormonally active agents in the environment and children's behavior: assessing effects on children's gender-dimorphic outcomes. Epidemiology 2003; 14:148-54. [PMID: 12606879 DOI: 10.1097/01.ede.0000050706.59049.59] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Early sex hormone exposure contributes to gender-dimorphic behavioral development in mammals, including humans. Environmental toxicants concentrated in contaminated sport fish can interfere with the actions of sex steroids. METHODS This study developed an outcome variable by combining gender-dimorphic behaviors that differentiates boys and girls. Offspring of participants in the New York State Angler Cohort Study (NYSACS) were targeted in a parent-report postal survey. Instruments were selected based on findings of gender differences in the general population. RESULTS A linear discriminant function model incorporating three gender behavior scales correctly classified the sex of 97.7% of children (252 boys and 234 girls) from a random NYSACS sample. The discriminant function was cross-validated by correctly classifying the sex of 98.4% of children (457 boys and 425 girls) from the remaining NYSACS cases and 97.6% of children (154 boys and 142 girls) from an independent school sample. Within-sex stepwise multiple regression analyses revealed that masculine behavior increased among boys with age and with the number of years of maternal sport fish consumption. In girls, older age and previous live-born siblings were associated with more masculine behavior, whereas feminine behavior increased with the duration of breast feeding. These associations were replicated in an independent sample. CONCLUSIONS A linear discriminant function effectively transformed the binary classification of sex (male-female) to a bipolar continuum of gender (masculinity-femininity). Findings from this study are consistent with the hypothesis that environmental contaminants contribute to shifts in gender-role behavior. Future investigations will need to account for competing explanations of this effect.
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Affiliation(s)
- David E Sandberg
- Department of Psychiatry, School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, and Pediatric Psychiatry and Psychology, Children's Hospital of Buffalo, 14222, USA.
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185
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Conrad CD, Grote KA, Hobbs RJ, Ferayorni A. Sex differences in spatial and non-spatial Y-maze performance after chronic stress. Neurobiol Learn Mem 2003; 79:32-40. [PMID: 12482677 DOI: 10.1016/s1074-7427(02)00018-7] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Chronic restraint is known to alter hippocampal CA3 dendritic morphology and spatial memory in male rats. The present study examined whether female rats, which exhibit different anatomical adaptations to chronic stress than those of males, would also show spatial memory impairments. Male and female Sprague-Dawley rats were restrained for 6 h/day for 21 days, a time frame previously demonstrated to cause hippocampal CA3 dendritic atrophy. The day after the last restraint session, rats were tested on a Y-maze, a habituation task that can be used to assess spatial memory. Chronic stress impaired Y-maze performance in both sexes without affecting levels of locomotion as measured by total arm entries in the first minute. However, Y-maze performance of stressed females improved in 2-5 min when chronically stressed males continued to show poor Y-maze performance. The enhanced Y-maze performance of chronically stressed females occurred when total arm entries were higher compared to the entries made by males. Therefore, correlations were performed between total arm entries and spatial memory in 1 and 2-5 min. In the first minute when control females demonstrated functional spatial memory, female controls with the lowest locomotor levels exhibited the best performance. The correlations for stressed females were not significant, and neither were the correlations for any group in 2-5 min. Overall, these results show important sex differences in response to chronic stress with females exhibiting an ability to recover quickly from deficits in Y-maze performance.
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Affiliation(s)
- Cheryl D Conrad
- Department of Psychology, Arizona State University, Tempe, AZ 85287-1104, USA.
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186
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Shors TJ, Miesegaes G. Testosterone in utero and at birth dictates how stressful experience will affect learning in adulthood. Proc Natl Acad Sci U S A 2002; 99:13955-60. [PMID: 12359876 PMCID: PMC129804 DOI: 10.1073/pnas.202199999] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Indexed: 11/18/2022] Open
Abstract
Exposure to an acute stressful event can enhance learning in male rats, whereas exposure to the same event dramatically impairs performance in females. Here we tested whether the presence of sex hormones during early development organizes these opposite effects of stress on learning in males vs. females. In the first experiment, males were castrated at birth whereas females were injected with testosterone. Rats were trained as adults on the hippocampal-dependent learning task of trace eyeblink conditioning. Performance in adult males that had been castrated at birth was still enhanced by exposure to an acute stressful experience. However, adult females injected with testosterone at birth responded in the opposite direction, i.e., exposure to the stressor that typically reduces performance instead enhanced their levels of conditioning. In the second experiment, exposure to testosterone was manipulated in utero by injecting pregnant females with a testosterone antagonist. After foster rearing, adult offspring were exposed to the stressor and trained on the hippocampal-dependent learning task of trace conditioning. Although performance in adult females was unaffected by antagonizing testosterone in utero, i.e., stress still reduced performance, the enhancement of conditioning after stress in adult males was prevented. Thus, the presence of sex hormones during gestation and development organizes whether and how acute stressful experience will affect the ability to acquire new information in adulthood. As with many sexual behaviors, these cognitive responses to stress appear to be masculinized by exposure to testosterone and feminized by its absence during very early development.
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Affiliation(s)
- Tracey J Shors
- Department of Psychology and Center for Collaborative Neuroscience, Rutgers University, Piscataway, NJ 08854-8020, USA.
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187
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Risk taking during exploration of a plus-maze is greater in adolescent than in juvenile or adult mice. Anim Behav 2002. [DOI: 10.1006/anbe.2002.4004] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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188
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Pocock VJ, Sales GD, Wilson CA, Milligan SR. Effects of perinatal octylphenol on ultrasound vocalization, behavior and reproductive physiology in rats. Physiol Behav 2002; 76:645-53. [PMID: 12127004 DOI: 10.1016/s0031-9384(02)00788-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A rodent diet containing paraffin wax was designed to administer the environmental estrogen octylphenol (OP) to nonpregnant, pregnant and lactating rats. The estrogenic activity of OP via this diet was first confirmed in ovariectomized adult animals: 20 mg OP/kg/day increased the mitoses in the vaginal epithelium, and 60 mg OP/kg/day stimulated mitoses in the uterine luminal epithelium. The effects on a variety of reproductive and nonreproductive parameters were then investigated in the offspring of dams fed OP (100-250 mg/kg/day during gestation and lactation). A number of modest reproductive and morphological effects observed in the offspring including decreased body weights in adults of both sexes, disrupted vaginal cyclicity and decreases in seminiferous tubule diameter and testis, kidney, spleen and ovary weights. Behavioral effects included increased sexual arousal in males, increased sexual motivation in females towards a female teaser and increased motor activity by females. Ultrasonic vocalizations by pups at Postnatal Day (PND) 7 were reduced in number and duration in both sexes. There were no effects of perinatal OP on ano-genital distance, prepuce separation, aggressive behavior or adult ultrasound vocalization. These observations confirm that the dietary intake of estrogenic amounts of OP during pregnancy and lactation can have a wide variety of effects in the offspring.
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Affiliation(s)
- Victoria J Pocock
- Endocrinology and Reproduction Research Group, School of Biomedical Sciences, Guy's Campus, King's College, London SE1 1U, UK
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189
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Abstract
Compared with apolipoprotein (apo) E2 and E3, apoE4 increases the risk of Alzheimer's disease (AD), but it remains unknown how apoE4 affects neuronal function. ApoE4 interacts with female gender, further increasing the risk of AD and decreasing treatment response. Female mice are also more susceptible to apoE4-induced impairments of spatial learning and memory than male mice. To assess the role of sex steroids in this process, we studied mice deficient in mouse apoE (Apoe(-/-)) and expressing human apoE4 or apoE3 in the brain at comparable levels. Even brief periods of androgen treatment improved the memory deficits of female apoE4 mice. Female apoE3 mice had no memory deficits and did not benefit from the treatment. ApoE4 male mice, which performed normally in a water-maze test at baseline, developed prominent deficits in spatial learning and memory after blockade of androgen receptors (ARs), whereas apoE3 male mice did not. Untreated apoE4 mice had significantly lower cytosolic AR levels in the neocortex than wild-type, Apoe(-/-), and apoE3 mice. Improved memory in androgen-treated female apoE4 mice was associated with increased cytosolic AR levels. Our findings suggest that apoE4 contributes to cognitive decline by reducing AR levels in the brain, and that stimulating AR-dependent pathways can reverse apoE4-induced cognitive deficits.
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190
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Febo M, Jiménez-Rivera CA, Segarra AC. Estrogen and opioids interact to modulate the locomotor response to cocaine in the female rat. Brain Res 2002; 943:151-61. [PMID: 12088849 DOI: 10.1016/s0006-8993(02)02748-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Estrogen is known to modulate the behavioral response to cocaine; however the mechanisms by which this is accomplished is unknown. In this study we examine one possible candidate, the endogenous opioid system. Adult Sprague-Dawley rats were ovariectomized (OVX), half received Silastic implants with estradiol benzoate (OVX-EB), the other half received empty implants (OVX). After 1 week, spontaneous locomotor and stereotyped activity was measured for 60 min using an automated system. On day 2, locomotor activity was recorded for 30 min. Rats were injected with saline (SAL) or naloxone (NAL) (2 mg/kg, i.p.) and activity measured for the next 20 min. Each of these groups were further subdivided, one that received a saline injection (SAL) and another that received a cocaine injection (COC) (15 mg/kg, i.p.). Locomotor and stereotyped activities were recorded for 60 min. This resulted in the following injection groups: SAL-SAL, NAL-SAL, SAL-COC and NAL-COC. During habituation, OVX rats displayed an overall higher level of activity than OVX-EB rats. Similar to what is observed in males, naloxone significantly reduced locomotion and stereotyped behavior but only in OVX rats. Estrogen administration to OVX rats abolished the effect of naloxone. Surprisingly, when naloxone was administered prior to cocaine, an increase in cocaine-induced locomotor and stereotyped activity was observed, but only in OVX-EB rats. These results indicate that opioid modulation of cocaine-induced locomotor and stereotype activity in the female differs from that reported in the male. In addition in the female, the effect of opioids on cocaine-induced locomotor behavior is dependent on plasma levels of estrogen.
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Affiliation(s)
- Marcelo Febo
- Department of Physiology, School of Medicine, University of Puerto Rico, PO Box 365067, San Juan, PR 00936, USA
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191
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Lehmann O, Jeltsch H, Lazarus C, Tritschler L, Bertrand F, Cassel JC. Combined 192 IgG-saporin and 5,7-dihydroxytryptamine lesions in the male rat brain: a neurochemical and behavioral study. Pharmacol Biochem Behav 2002; 72:899-912. [PMID: 12062580 DOI: 10.1016/s0091-3057(02)00752-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In a previous experiment [Eur J Neurosci 12 (2000) 79], combined intracerebroventricular injections of 5,7-dihydroxytryptamine (5,7-DHT; 150 microg) and 192 IgG-saporin (2 microg) in female rats produced working memory impairments, which neither single lesion induced. In the present experiment, we report on an identical approach in male rats. Behavioral variables were locomotor activity, T-maze alternation, beam-walking, Morris water-maze (working and reference memory) and radial-maze performances. 192 IgG-saporin reduced cholinergic markers in the frontoparietal cortex and the hippocampus. 5,7-DHT lesions reduced serotonergic markers in the cortex, hippocampus and striatum. Cholinergic lesions induced motor deficits, hyperactivity and reduced T-maze alternation, but had no other effect. Serotonergic lesions only produced hyperactivity and reduced T-maze alternation. Beside the deficits due to cholinergic lesions, rats with combined lesions also showed impaired radial-maze performances. We confirm that 192 IgG-saporin and 5,7-DHT injections can be combined to produce concomitant damage to cholinergic and serotonergic neurons in the brain. In female rats, this technique enabled to show that interactions between serotonergic and basal forebrain cholinergic mechanisms play an important role in cognitive functions. The results of the present experiment in male rats are not as clear-cut, although they are not in obvious contradiction with our previous results in females.
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Affiliation(s)
- Olivia Lehmann
- LN2C, UMR 7521 CNRS/Université Louis Pasteur, IFR de Neurosciences 37, 12 rue Goethe, F-67000 Strasbourg, France
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192
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Silbergeld EK, Flaws JA, Brown KM. Organizational and activational effects of estrogenic endocrine disrupting chemicals. CAD SAUDE PUBLICA 2002; 18:495-504. [PMID: 11923891 DOI: 10.1590/s0102-311x2002000200014] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endocrine disruption is a hypothesis of common mode of action that may define a set of structurally varied chemicals, both natural and synthetic. Their common mode of action may suggest that they produce or contribute to similar toxic effects, although this has been difficult to demonstrate. Insights from developmental biology suggest that development of hormone sensitive systems, such as the brain and the genitourinary tract, may be particularly sensitive to EDCs. Because these systems are both organized and later activated by hormones, the brain and vagina may be valuable model systems to study the toxicity of EDCs in females and to elucidate mechanisms whereby early exposures appear to affect long term function.
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Affiliation(s)
- Ellen K Silbergeld
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Baltimore, MD 21205, USA.
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193
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Zareba G, Hojo R, Zareba KM, Watanabe C, Markowski VP, Baggs RB, Weiss B. Sexually dimorphic alterations of brain cortical dominance in rats prenatally exposed to TCDD. J Appl Toxicol 2002; 22:129-37. [PMID: 11920938 DOI: 10.1002/jat.839] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Sexually dimorphic patterns of cortical lateralization are documented extensively in both human and animal brains. Male rats tend to exhibit pronounced right hemisphere dominance compared with females, whereas females typically exhibit more diffuse lateralization patterns and greater left hemisphere bias compared with males. Prenatal TCDD (2,3,7,8 tetrachlorodibenzo-p-dioxin) exposure produces demasculinization of male offspring sexual behavior. In previous studies, we showed a reversal of cortical dominance in rats after prenatal TCDD exposure on gestational day 18 (GD 18). The current study aimed to determine the nature of changes observed in rats exposed to TCDD on GD 8. In addition, locomotor activity was measured in male and female offspring on postnatal day (PND) 30, 60 and 90. Pregnant females were given, via gavage, a single dose of 0, 20, 60 or 180 ng kg(-1) TCDD on GD 8. Cortical depth measurements were taken in selected brain regions in offspring 3 months old that had been exposed to the 180 ng kg(-1) dose. Areas 2, 3, 17, 18a and 39 at bregmas -1.8, -3.8 and -5.8 were analyzed by quantifying digitized, enhanced images produced by a photomicroscope fitted with a special color camera. In both male and female offspring, cortical thicknesses in control brains exceeded those of exposed brains. In several brain areas of male offspring exposed to TCDD, right hemispheric dominance reversed to left hemispheric dominance. Female offspring brains showed a contrary move towards right hemisphere dominance. Motor activity in juvenile and mature animals did not differ among dose groups. These data demonstrate that prenatal exposure to TCDD reduces cortical thickness and alters the normal pattern of cortical asymmetry, a finding consistent with the sexually dimorphic behavioral effects induced by this agent.
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Affiliation(s)
- Grazyna Zareba
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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194
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Palanza P, Morellini F, Parmigiani S, vom Saal FS. Ethological methods to study the effects of maternal exposure to estrogenic endocrine disrupters: a study with methoxychlor. Neurotoxicol Teratol 2002; 24:55-69. [PMID: 11836072 DOI: 10.1016/s0892-0362(01)00191-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There has been increasing interest, both at the scientific and regulatory level, in the use of ethological methods for evaluating neural effects of endocrine disrupters. We present a series of ethological studies on the effects of maternal exposure to low, environmentally relevant doses (0.02, 0.2, and 2 microg/g mother bw/day) of the estrogenic pesticide methoxychlor (MXC) on behavior. From gestation day 11 to 17, female mice spontaneously drank oil with or without MXC; their maternal behavior was examined from postpartum days 2 to 15. MXC treatment during pregnancy produced slight changes in the expression of maternal behavior: females fed the lower MXC dose spent less time nursing the pups as compared to control dams. Their maternally exposed offspring were subjected to a series of behavioral tests at different ages. Maternal exposure to MXC affected behavioral responses to novelty in both sexes at periadolescence. The onset of male intrasex aggression was delayed in males prenatally exposed to low doses of MXC, since exposed males showed low levels of aggressive interactions during early adolescence but not after they reached adulthood. When adults, MXC-exposed females, but not males showed increased exploration in an unfamiliar open-field. While a sex difference was observed in the control group, with males being significantly more active in the open field than females, prenatal treatment with some MXC doses tended to decrease the sexual dimorphism in activity levels in the novel environment. Ethology, as the evolutionary study of behavior, may provide a framework for integrating a functional perspective (i.e., evolutionary significance) to studies on proximate mechanisms that can account for behavioral alterations induced by developmental exposure to endocrine disrupters.
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Affiliation(s)
- P Palanza
- Department of Evolutionary and Functional Biology, Parma University, Parco Area delle Scienze 11A, 43100 Parma, Italy.
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195
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Liben LS, Susman EJ, Finkelstein JW, Chinchilli VM, Kunselman S, Schwab J, Semon Dubas J, Demers LM, Lookingbill G, D'Arcangelo MR, Krogh HR, Kulin HE. The effects of sex steroids on spatial performance: A review and an experimental clinical investigation. Dev Psychol 2002. [DOI: 10.1037/0012-1649.38.2.236] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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196
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Perrot-Sinal TS, Davis AM, McCarthy MM. Developmental sex differences in glutamic acid decarboxylase (GAD(65)) and the housekeeping gene, GAPDH. Brain Res 2001; 922:201-8. [PMID: 11743950 DOI: 10.1016/s0006-8993(01)03167-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Previous work has demonstrated that the GABAergic system is involved in sexual differentiation of the rodent hypothalamus. The present study was designed to further examine this involvement by investigating developmental sex differences in GAD(65) protein levels in hypothalamic and extrahypothalamic brain regions known to be sexually dimorphic in adulthood. Brain nuclei were micro-dissected and GAD(65) protein levels were quantified using western immunoblotting. Sex differences in levels of GAD(65) were found in the dorsomedial nucleus and preoptic area of the hypothalamus and also the medial amygdaloid nucleus and CA1 subfield of the hippocampus. Unexpectedly, there were sex differences in protein levels of the housekeeping gene, GAPDH, cautioning against the use of GAPDH for standardizing protein samples during western immunoblotting.
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Affiliation(s)
- T S Perrot-Sinal
- Department of Physiology, BRB 5-020, University of Maryland School of Medicine, 655 West Baltimore Street, Baltimore, MD 21201, USA.
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197
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Hughes RN. Responsiveness to brightness change in hooded rats: effects of sex and procedure. Behav Processes 2001; 55:143-155. [PMID: 11483352 DOI: 10.1016/s0376-6357(01)00177-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In an investigation of recognition memory involving a preference test, hooded rats of both sexes were individually confined to the stem and choice area of a T- or Y-maze by means of clear Perspex barriers across each arm entrance that enabled the subjects to see into but not enter the arms. Following removal of the barriers and changing of one arm to opposite brightness, the first arm entered and the number of entries of and time spent in each arm were recorded. In the first experiment, rats entered first the arm that had been changed. During the first minute of observation, they also entered this novel arm more often and spent more time in it than the unchanged arm, irrespective of the type of change. In a second experiment, when the change was from one arm black and the other white to two black arms, more responsiveness occurred after 6-min prior exposure (without access) than after 3 min. In both experiments, the nature of the apparatus (T- or Y-maze) affected several outcomes, but the most significant influence was of the sex of the subjects. Females appeared less responsive to change than males as determined by entries of and time spent in the changed arm. Rather than inferiority of females in recognition or spatial memory, the sex effects were most likely due to their more rapid habituation to novelty possibly assisted by superior visual exploration capacities.
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Affiliation(s)
- R N. Hughes
- Department of Psychology, University of Canterbury, PB 4800, Christchurch, New Zealand
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198
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van Luijtelaar G, Budziszewska B, Jaworska-Feil L, Ellis J, Coenen A, Lasoń W. The ovarian hormones and absence epilepsy: a long-term EEG study and pharmacological effects in a genetic absence epilepsy model. Epilepsy Res 2001; 46:225-39. [PMID: 11518624 DOI: 10.1016/s0920-1211(01)00277-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In the first experiment, the relationship between the phase of the estrous cycle and the number of spontaneously occurring spike-wave discharges was investigated in WAG/Rij rats, a model for generalized absence epilepsy. The electroencephalogram (EEG) was continuously recorded for 96 h in eight rats chronically equipped with cortical EEG electrodes. A circadian pattern emerged for the number of spike-wave discharges: a nadir during the first hours of the light period, and an acrophase during the first hours of the dark period. This daily maximum was increased at proestrus day compared with the other days of the cycle, when the plasma level of progesterone is enhanced specifically at these hours of this day. This suggests that progesterone enhances spike-wave discharges. There was no difference in the first few hours of the light period in the number of spike-wave discharges between proestrus and the three other days, suggesting that estradiol has no effect on spike-wave discharges. In the second study, the effects of the systemic administration of progesterone and 17 beta-estradiol on spike-wave discharges and spontaneous behavior were investigated. It was shown that progesterone (20 and 30 mg/kg) but not estradiol (0.17-1.5 mg/kg) increased the number and total duration of spike-wave discharges. On the other hand, injection of RU 38486 (10 and 30 mg/kg), an antagonist of intracellular progesterone receptors, had no effect on spike-wave discharges and did not block the stimulatory effect of progesterone. The antagonist of 17 beta-estradiol tamoxifen (1 and 3 mg/kg) did not evoke alterations in the number or duration of spike-wave discharges. Our results indicate that progesterone aggravates spike-wave discharges, but is not mediated through intracellular receptors. Since progesterone is rapidly metabolized in the brain to the positive modulator of GABA(A) receptor allopregnanolone, which increases spike-wave discharges in WAG/Rij rats, it is possible that the epileptiformic effects of progesterone are mediated through this metabolite.
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Affiliation(s)
- G van Luijtelaar
- Department of Physiological Psychology, NICI, University of Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands.
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199
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Ivanova T, Beyer C. Pre- and postnatal expression of brain-derived neurotrophic factor mRNA/protein and tyrosine protein kinase receptor B mRNA in the mouse hippocampus. Neurosci Lett 2001; 307:21-4. [PMID: 11516565 DOI: 10.1016/s0304-3940(01)01905-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is implicated in the control of hippocampal development. In this study, we have analyzed the developmental expression of BDNF mRNA/protein and its receptor tyrosine protein kinase receptor (trk) B mRNA in the mouse hippocampus by competitive reverse transcription/polymerase chain reaction and enzyme-linked immunoassay. Cell-type specificity of BDNF/trkB expression was studied in primary hippocampal cultures. BDNF levels increased stepwise from embryonic day 15 until the second postnatal week, whereas trkB expression was stable throughout development. Neurons and astrocytes expressed both BDNF and trkB. Our data suggest that developmental BDNF action mainly occurs postnatally and indicates that hippocampal neurons and astroglia not only produce BDNF but also appear to be targets for BDNF.
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Affiliation(s)
- T Ivanova
- Abteilung Anatomie und Zellbiologie, Universität Ulm, D-89069 Ulm, Germany
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200
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Abstract
The current study investigated ovarian modulation of the locomotor response to cocaine in rats. Ovariectomy in females lowered the response to cocaine (10 mg/kg i.p.), whereas castration did not change that of males. The locomotor responses of prepubertal males and females to cocaine were similar. However, the postpubertal sex difference resulted from a fall in cocaine-stimulated locomotion in males rather than a rise in females. Neonatal testosterone treatment of female rat pups decreased the response to cocaine in adulthood. These findings suggest that both the activational and organizational effects of gonadal steroids contribute to the greater response of females to cocaine.
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Affiliation(s)
- C M Kuhn
- Department of Pharmacology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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