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Pedrón VT, Canero EM, Varani AP, Aon AJ, Maldonado R, Balerio GN. Baclofen prevents morphine rewarding effects and associated biochemical alterations in male and female mice. Eur J Pharmacol 2024; 979:176768. [PMID: 39002637 DOI: 10.1016/j.ejphar.2024.176768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 06/20/2024] [Accepted: 06/23/2024] [Indexed: 07/15/2024]
Abstract
Previous studies from our laboratory have shown sex differences in the behavioral, molecular, and neurochemical manifestations of morphine withdrawal and they were related to an increased sensitivity to morphine effects in males. In addition, we observed an interaction between the GABAergic and opioid systems that could also be sex-dependent. Baclofen, a GABAB receptor agonist, prevented the somatic expression and the molecular and neurochemical changes induced by morphine withdrawal syndrome in mice. On the contrary, little is known about baclofen effects in the rewarding properties of morphine in male and female mice. The present study aimed to explore the effect of baclofen (1, 2 and 3 mg/kg, i.p.) pretreatment in the rewarding effects induced by morphine (7 mg/kg, s.c.) and its effect on c-Fos and brain-derived neurotrophic factor (BDNF) expression induced by the rewarding properties of morphine in prepubertal male and female mice. Baclofen (2 mg/kg) pretreatment prevented the rewarding effects of morphine only in male mice, while baclofen (3 mg/kg) reduced these effects in both sexes. Moreover, the rewarding effects of morphine were associated with a decrease of BDNF and c-Fos expression cingulate cortex, nucleus accumbens shell, cornu ammonis 1 (CA1), and cornu ammonis 3 (CA3) areas of the hippocampus only in male mice. In addition, baclofen pretreatment prevented these changes in BDNF, but not in c-Fos expression. In conclusion, our results show that GABAB receptors have a regulatory role in the rewarding effects of morphine that could be of interest for a potential future therapeutic application in opioid use disorders.
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Affiliation(s)
- Valeria T Pedrón
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
| | - Eliana M Canero
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
| | - Andrés P Varani
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
| | - Amira J Aon
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
| | - Rafael Maldonado
- Laboratori de Neurofarmacologia, Facultat de Ciències de La Salut I de La Vida, Universitat Pompeu Fabra, C/Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Graciela N Balerio
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Investigaciones Farmacológicas (ININFA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina; Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Cátedra de Farmacología, Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina.
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2
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Mitchell JR, Vincelette L, Tuberman S, Sheppard V, Bergeron E, Calitri R, Clark R, Cody C, Kannan A, Keith J, Parakoyi A, Pikus M, Vance V, Ziane L, Brenhouse H, Laine MA, Shansky RM. Behavioral and neural correlates of diverse conditioned fear responses in male and female rats. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.20.608817. [PMID: 39229164 PMCID: PMC11370446 DOI: 10.1101/2024.08.20.608817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Pavlovian fear conditioning is a widely used tool that models associative learning in rodents. For decades the field has used predominantly male rodents and focused on a sole conditioned fear response: freezing. However, recent work from our lab and others has identified darting as a female-biased conditioned response, characterized by an escape-like movement across a fear conditioning chamber. It is also accompanied by a behavioral phenotype: Darters reliably show decreased freezing compared to Non-darters and males and reach higher velocities in response to the foot shock ("shock response"). However, the relationship between shock response and conditioned darting is not known. This study investigated if this link is due to differences in general processing of aversive stimuli between Darters, Non-darters and males. Across a variety of modalities, including corticosterone measures, the acoustic startle test, and sensitivity to thermal pain, Darters were found not to be more reactive or sensitive to aversive stimuli, and, in some cases, they appear less reactive to Non-darters and males. Analyses of cFos activity in regions involved in pain and fear processing following fear conditioning identified discrete patterns of expression among Darters, Non-darters, and males exposed to low and high intensity foot shocks. The results from these studies further our understanding of the differences between Darters, Non-darters and males and highlight the importance of studying individual differences in fear conditioning as indicators of fear state.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Mikaela A Laine
- Northeastern University, Boston, MA
- Smith College, Northampton, MA
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3
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Sexually Dimorphic Expression of Fear-conditioned Analgesia in Rats and Associated Alterations in the Endocannabinoid System in the Periaqueductal Grey. Neuroscience 2021; 480:117-130. [PMID: 34774710 DOI: 10.1016/j.neuroscience.2021.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/16/2021] [Accepted: 11/02/2021] [Indexed: 11/20/2022]
Abstract
The endocannabinoid system within the periaqueductal grey (PAG) has been implicated in fear-conditioned analgesia (FCA), the profound suppression of pain upon re-exposure to a context previously paired with an aversive stimulus. Since the endocannabinoid and nociceptive systems exhibit sexual dimorphism, the aim of the present study was to assess possible sex differences in the expression of FCA, fear in the presence of nociceptive tone, and associated sex-dependent alterations in the endocannabinoid system within the PAG. Male and female Sprague-Dawley rats received footshock (10 × 1s; 0.4 mA; every 60 s) or no-footshock in a conditioning arena and 23.5 h later received intraplantar injection of formalin (2.5%) under brief isoflourane anaesthetic into the right hind paw. Nociceptive and fear-related behaviours were assessed 30 min later. Levels of endocannabinoids, N-acylethanolamines and neurotransmitters in the PAG were assessed by LC-MS/MS and expression of endocannabinoid system-related proteins by Western immunoblotting. Male, but not female, rats exhibited robust FCA and greater expression of fear-related behaviours than females. Fear-conditioned formalin-treated males, but not females, had higher levels of N-oleoylethanolamine (OEA) and γ-aminobutyric acid (GABA) in the PAG, compared with non-fear-conditioned controls. There was no effect of fear conditioning on the levels of FAAH or CB1 receptor expression (CB1R) in the PAG of male or female formalin-treated rats. Non-fear-conditioned females had higher levels of CB1R and PPARγ expression than non-fear-conditioned male counterparts. In summary, our results provide evidence of sexual dimorphism in the expression of FCA and fear-related behaviours, and associated alterations in components of the endocannabinoid system and GABA within the PAG.
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4
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Hoffman AN, Watson SL, Makridis AS, Patel AY, Gonzalez ST, Ferguson L, Giza CC, Fanselow MS. Sex Differences in Behavioral Sensitivities After Traumatic Brain Injury. Front Neurol 2020; 11:553190. [PMID: 33324313 PMCID: PMC7724082 DOI: 10.3389/fneur.2020.553190] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 10/30/2020] [Indexed: 01/15/2023] Open
Abstract
Traumatic brain injury (TBI) is associated with high rates of post-injury psychiatric and neurological comorbidities. TBI is more common in males than females despite females reporting more symptoms and longer recovery following TBI and concussion. Both pain and mental health conditions like anxiety and post-traumatic stress disorder (PTSD) are more common in women in the general population, however the dimorphic comorbidity in the TBI population is not well-understood. TBI may predispose the development of maladaptive anxiety or PTSD following a traumatic stressor, and the impact of sex on this interaction has not been investigated. We have shown that white noise is noxious to male rats following fluid percussion injury (FPI) and increases fear learning when used in auditory fear conditioning, but it is unclear whether females exhibit a similar phenotype. Adult female and male rats received either lateral FPI or sham surgery and 48 h later received behavioral training. We first investigated sex differences in response to 75 dB white noise followed by white noise-signaled fear conditioning. FPI groups exhibited defensive behavior to the white noise, which was significantly more robust in females, suggesting FPI increased auditory sensitivity. In another experiment, we asked how FPI affects contextual fear learning in females and males following unsignaled footshocks of either strong (0.9 mA) or weaker (0.5 mA) intensity. We saw that FPI led to rapid acquisition of contextual fear compared to sham. A consistent pattern of increased contextual fear after TBI was apparent in both sexes across experiments under differing conditioning protocols. Using a light gradient open field task we found that FPI females showed a defensive photophobia response to light, a novel finding supporting TBI enhanced sensory sensitivity across modalities in females. General behavioral differences among our measures were observed between sexes and discussed with respect to interpretations of TBI effects for each sex. Together our data support enhanced fear following a traumatic stressor after TBI in both sexes, where females show greater sensitivity to sensory stimuli across multiple modalities. These data demonstrate sex differences in emergent defensive phenotypes following TBI that may contribute to comorbid PTSD, anxiety, and other neurological comorbidities.
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Affiliation(s)
- Ann N Hoffman
- Neurosurgery, Brain Injury Research Center, University of California, Los Angeles, Los Angeles, CA, United States.,Psychology, University of California, Los Angeles, Los Angeles, CA, United States.,University of California, Los Angeles Steve Tisch BrainSPORT Program, Los Angeles, CA, United States.,Staglin Center for Brain and Behavioral Health, University of California, Los Angeles, Los Angeles, CA, United States
| | - Sonya L Watson
- Neurosurgery, Brain Injury Research Center, University of California, Los Angeles, Los Angeles, CA, United States.,Psychology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Anna S Makridis
- Psychology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Anisha Y Patel
- Psychology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Sarah T Gonzalez
- Psychology, University of California, Los Angeles, Los Angeles, CA, United States.,Staglin Center for Brain and Behavioral Health, University of California, Los Angeles, Los Angeles, CA, United States
| | - Lindsay Ferguson
- Neurosurgery, Brain Injury Research Center, University of California, Los Angeles, Los Angeles, CA, United States.,University of California, Los Angeles Steve Tisch BrainSPORT Program, Los Angeles, CA, United States
| | - Christopher C Giza
- Neurosurgery, Brain Injury Research Center, University of California, Los Angeles, Los Angeles, CA, United States.,University of California, Los Angeles Steve Tisch BrainSPORT Program, Los Angeles, CA, United States.,Division of Neurology, Department of Pediatrics, University of California, Los Angeles Mattel Children's Hospital, Los Angeles, CA, United States
| | - Michael S Fanselow
- Psychology, University of California, Los Angeles, Los Angeles, CA, United States.,Staglin Center for Brain and Behavioral Health, University of California, Los Angeles, Los Angeles, CA, United States.,Department of Psychiatry and Biobehavioral Science, Los Angeles, CA, United States
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5
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Pedrón VT, Varani AP, Balerio GN. Baclofen prevents the elevated plus maze behavior and BDNF expression during naloxone precipitated morphine withdrawal in male and female mice. Synapse 2016; 70:187-97. [DOI: 10.1002/syn.21886] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 12/26/2015] [Accepted: 01/11/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Valeria T. Pedrón
- Instituto de Investigaciones Farmacológicas (UBA-CONICET); Junín 956, 5° piso (C1113AAD) Buenos Aires Argentina
| | - André P. Varani
- Instituto de Investigaciones Farmacológicas (UBA-CONICET); Junín 956, 5° piso (C1113AAD) Buenos Aires Argentina
- Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires; Junín 956, 5° piso (C1113AAD) Buenos Aires Argentina
| | - Graciela N. Balerio
- Instituto de Investigaciones Farmacológicas (UBA-CONICET); Junín 956, 5° piso (C1113AAD) Buenos Aires Argentina
- Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires; Junín 956, 5° piso (C1113AAD) Buenos Aires Argentina
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6
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Miguez G, Laborda MA, Miller RR. Classical conditioning and pain: conditioned analgesia and hyperalgesia. Acta Psychol (Amst) 2014; 145:10-20. [PMID: 24269884 PMCID: PMC3877420 DOI: 10.1016/j.actpsy.2013.10.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 10/16/2013] [Accepted: 10/23/2013] [Indexed: 11/25/2022] Open
Abstract
This article reviews situations in which stimuli produce an increase or a decrease in nociceptive responses through basic associative processes and provides an associative account of such changes. Specifically, the literature suggests that cues associated with stress can produce conditioned analgesia or conditioned hyperalgesia, depending on the properties of the conditioned stimulus (e.g., contextual cues and audiovisual cues vs. gustatory and olfactory cues, respectively) and the proprieties of the unconditioned stimulus (e.g., appetitive, aversive, or analgesic, respectively). When such cues are associated with reducers of exogenous pain (e.g., opiates), they typically increase sensitivity to pain. Overall, the evidence concerning conditioned stress-induced analgesia, conditioned hyperalagesia, conditioned tolerance to morphine, and conditioned reduction of morphine analgesia suggests that selective associations between stimuli underlie changes in pain sensitivity.
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Affiliation(s)
| | - Mario A Laborda
- State University of New York at Binghamton, USA; Universidad de Chile, Chile.
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7
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Sherrill LK, Berthold C, Koss WA, Juraska JM, Gulley JM. Sex differences in the effects of ethanol pre-exposure during adolescence on ethanol-induced conditioned taste aversion in adult rats. Behav Brain Res 2011; 225:104-9. [PMID: 21767576 DOI: 10.1016/j.bbr.2011.07.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 06/29/2011] [Accepted: 07/04/2011] [Indexed: 11/15/2022]
Abstract
Alcohol use, which typically begins during adolescence and differs between males and females, is influenced by both the rewarding and aversive properties of the drug. One way adolescent alcohol use may modulate later consumption is by reducing alcohol's aversive properties. Here, we used a conditioned taste aversion (CTA) paradigm to determine if pre-exposure to alcohol (ethanol) during adolescence would attenuate ethanol-induced CTA assessed in adulthood in a sex-dependent manner. Male and female Long-Evans rats were given intraperitoneal (i.p.) injections of saline or 3.0g/kg ethanol in a binge-like pattern during postnatal days (PD) 35-45. In adulthood (>PD 100), rats were given access to 0.1% saccharin, followed by saline or ethanol (1.0 or 1.5g/kg, i.p.), over four conditioning sessions. We found sex differences in ethanol-induced CTA, with males developing a more robust aversion earlier in conditioning. Sex differences in the effects of pre-exposure were also evident: males, but not females, showed an attenuated CTA in adulthood following ethanol pre-exposure, which occurred approximately nine weeks earlier. Taken together, these findings indicate that males are more sensitive to the aversive properties of ethanol than females. In addition, the ability of pre-exposure to the ethanol US to attenuate CTA is enhanced in males compared to females.
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Affiliation(s)
- Luke K Sherrill
- Department of Psychology, University of Illinois at Urbana-Champaign, 603 E. Daniel St., Champaign, IL 61820, USA
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Moore MD, Cushman J, Chandra D, Homanics GE, Olsen RW, Fanselow MS. Trace and contextual fear conditioning is enhanced in mice lacking the alpha4 subunit of the GABA(A) receptor. Neurobiol Learn Mem 2009; 93:383-7. [PMID: 20018248 DOI: 10.1016/j.nlm.2009.12.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 12/03/2009] [Accepted: 12/10/2009] [Indexed: 11/29/2022]
Abstract
The GABA(A)R alpha4 subunit is highly expressed in the dentate gyrus region of the hippocampus at predominantly extra synaptic locations where, along with the GABA(A)R delta subunit, it forms GABA(A) receptors that mediate a tonic inhibitory current. The present study was designed to test hippocampus-dependent and hippocampus-independent learning and memory in GABA(A)R alpha4 subunit-deficient mice using trace and delay fear conditioning, respectively. Mice were of a mixed C57Bl/6J X 129S1/X1 genetic background from alpha4 heterozygous breeding pairs. The alpha4-knockout mice showed enhanced trace and contextual fear conditioning consistent with an enhancement of hippocampus-dependent learning and memory. These enhancements were sex-dependent, similar to previous studies in GABA(A)R delta knockout mice, but differences were present in both males and females. The convergent findings between alpha4 and delta knockout mice suggests that tonic inhibition mediated by alpha4betadelta GABA(A) receptors negatively modulates learning and memory processes and provides further evidence that tonic inhibition makes important functional contributions to learning and behavior.
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Affiliation(s)
- M D Moore
- Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, CA, USA
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9
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Toufexis DJ, Myers KM, Bowser ME, Davis M. Estrogen disrupts the inhibition of fear in female rats, possibly through the antagonistic effects of estrogen receptor alpha (ERalpha) and ERbeta. J Neurosci 2007; 27:9729-35. [PMID: 17804633 PMCID: PMC6672956 DOI: 10.1523/jneurosci.2529-07.2007] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 07/11/2007] [Accepted: 07/11/2007] [Indexed: 12/31/2022] Open
Abstract
The ambiguous role of estrogen in emotional learning may result from opposing actions of estrogen receptor alpha (ERalpha) and ERbeta. Using a fear-conditioning paradigm called the AX+, BX- discrimination, in which cue A comes to elicit fear and cue B becomes a safety signal, we examined the effect of 17beta-estradiol (E) and selective ERalpha and ERbeta agonists on excitatory and inhibitory fear learning. Gonadectomized (GDX) male and female rats implanted with E or selective ERalpha or ERbeta agonists were trained on the AX+, BX- discrimination and tested periodically to A, B, and AB. GDX sham-implanted male and female rats and GDX E-implanted males, but not GDX E-implanted females, exhibited less fear to AB than to A, suggesting that estrogen interferes with generalization of safety signals in female rats. ERalpha and ERbeta agonists disrupted discrimination learning in both sexes. ERalpha-implanted groups had higher fear responses to all cues than did ERbeta-implanted groups, suggesting that these two receptors have opposing effects in aversive discrimination learning. In contrast, neither E nor ERalpha and ERbeta agonists affected single-cue fear conditioning in either sex. These data suggest that E does not enhance fear in emotional learning but acts to disrupt the inhibition of fear in females only.
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Affiliation(s)
- Donna J Toufexis
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, and The Center for Behavioral Neuroscience, Atlanta, Georgia 30329, USA.
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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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Toufexis DJ, Myers KM, Davis M. The effect of gonadal hormones and gender on anxiety and emotional learning. Horm Behav 2006; 50:539-49. [PMID: 16904674 DOI: 10.1016/j.yhbeh.2006.06.020] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 06/20/2006] [Accepted: 06/21/2006] [Indexed: 10/24/2022]
Abstract
Disorders of anxiety and fear dysregulation are highly prevalent. These disorders affect women approximately 2 times more than they affect men, occur predominately during a woman's reproductive years, and are especially prevalent at times of hormonal flux. This implies that gender differences and sex steroids play a key role in the regulation of anxiety and fear. However, the underlying mechanism by which these factors regulate emotional states in either sex is still largely unknown. This review discusses animal studies describing sex-differences in and gonadal steroid effects on affect and emotional learning. The effects of gonadal hormones on the modulation of anxiety, with particular emphasis on progesterone's ability to reduce the responsiveness of female rats to corticotropin releasing factor and the sex-specific effect of testosterone in the reduction of anxiety in male rats, is discussed. In addition, gonadal hormone and gender modulation of emotional learning is considered and preliminary data are presented showing that estrogen (E2) disrupts fear learning in female rats, probably through the antagonistic effect of ERalpha and ERbeta activation.
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Affiliation(s)
- Donna J Toufexis
- Emory University, Department of Psychiatry, Yerkes National Primate Center, 954 Gatewood Drive NE, Atlanta, GA 30329, USA.
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12
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Diaz SL, Kemmling AK, Rubio MC, Balerio GN. Morphine withdrawal syndrome: Involvement of the dopaminergic system in prepubertal male and female mice. Pharmacol Biochem Behav 2005; 82:601-7. [PMID: 16325246 DOI: 10.1016/j.pbb.2005.10.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 10/05/2005] [Accepted: 10/20/2005] [Indexed: 11/23/2022]
Abstract
Morphine (MOR) withdrawal signs are more marked in males than in females. Considering that the influence of the dopaminergic system on these differences is unclear, we analyzed dopamine (DA) and dihydroxyphenylacetic-acid (DOPAC) brain levels during naloxone (NAL)-precipitated withdrawal as well as the involvement of D(1) and D(2) receptors in the expression of MOR withdrawal in either sex. Prepubertal Swiss-Webster mice received MOR (2 mg/kg, i.p.) twice daily for 9 days. On the tenth day, dependent animals received NAL (6 mg/kg, i.p.) after MOR and were sacrificed 30 min later. DA and DOPAC concentrations were determined in different brain areas using HPLC with electrochemical detection. Other pool of mice received either a D(1) (SCH 23390; 0.2 mg/kg, i.p.) or D(2) (raclopride; 0.3 mg/kg, i.p.) receptor antagonist before NAL and withdrawal signs were evaluated. DA and DOPAC levels only decreased in striatum and cortex of withdrawn males. Conversely, both DA receptor antagonists decreased the expression of MOR withdrawal signs in either sex. The neurochemical sex differences described here could partially explain the behavioral sex differences observed during MOR withdrawal. Additionally, SCH-23390 and raclopride effects suggest an important role of both DA receptors in the expression of MOR withdrawal in males and females.
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Affiliation(s)
- Silvina L Diaz
- Instituto de Investigaciones Farmacológicas (CONICET), Buenos Aires, Argentina
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13
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Toufexis DJ, Davis C, Hammond A, Davis M. Progesterone attenuates corticotropin-releasing factor-enhanced but not fear-potentiated startle via the activity of its neuroactive metabolite, allopregnanolone. J Neurosci 2005; 24:10280-7. [PMID: 15537900 PMCID: PMC6730196 DOI: 10.1523/jneurosci.1386-04.2004] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Intact female rats and ovariectomized (OVX) rats with different ovarian steroid replacement regimens were tested for changes in corticotropin-releasing factor (CRF)-enhanced startle (increased acoustic startle amplitude after intracerebroventricular infusion of 1 mug of CRF). OVX rats injected with estradiol (E) followed by progesterone (P) showed a blunted CRF-enhanced startle effect compared with OVX and E-injected rats. CRF-enhanced startle also was reduced significantly in lactating females (high endogenous P levels) compared with cycling rats (low to moderate P levels), as well as in non-E-primed rats when P was administered acutely (4 hr before testing) or chronically (7 d P replacement). The ability of P to attenuate CRF-enhanced startle was probably mediated by its metabolite allopregnanolone [tetrahydroprogesterone (THP)], because THP itself had a similar effect, and chronic administration of medroxyprogesterone, which is not metabolized to THP, did not blunt CRF-enhanced startle but instead slightly increased it. These data suggest that P blunts CRF-enhanced startle through a mechanism involving its neuroactive metabolite THP, although a role for the P receptor cannot be completely ruled out. Finally, neither chronic P replacement nor acute THP affected fear-potentiated startle, suggesting that P metabolites have an effect on the bed nucleus of the stria terminalis and anxiety rather than on the amygdala and stimulus-specific fear.
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Affiliation(s)
- Donna J Toufexis
- Department of Psychiatry and Behavioral Sciences and The Center for Behavioral Neuroscience, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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King JA, De Oliveira WL, Patel N. Deficits in testosterone facilitate enhanced fear response. Psychoneuroendocrinology 2005; 30:333-40. [PMID: 15694113 DOI: 10.1016/j.psyneuen.2004.09.005] [Citation(s) in RCA: 31] [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: 02/16/2004] [Revised: 04/10/2004] [Accepted: 09/30/2004] [Indexed: 11/29/2022]
Abstract
Testosterone has been implicated in many behaviors related to sexual and reproductive function, but its role in fear responses is unclear. Studies in both humans and animals have linked altered testosterone concentrations to externalizing behaviors like aggression and violence, but less to more internalizing behaviors like fear. Therefore, the current study was designed to investigate the effects of testosterone on innate fear response in male rats. TMT (2,5-dihydo-2,4,5-trimethylthiazoline), a chemical extracted from fox feces, was used to elicit a fear response in the male rats with normal and diminished levels of testosterone. Behavioral indices such as in freezing response, and fear-induced analgesia were monitored in response to TMT. The results demonstrate that deficits in testosterone resulted in a significant increase in the freezing time and fear-induced analgesia. These studies suggest that testosterone decline may have a significant effect on increasing innate fear response and fear-induced enhancement of analgesia in male rats.
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Affiliation(s)
- Jean A King
- Department of Psychiatry, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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Riazi K, Honar H, Homayoun H, Rashidi N, Dehghani M, Sadeghipour H, Gaskari SA, Dehpour AR. Sex and estrus cycle differences in the modulatory effects of morphine on seizure susceptibility in mice. Epilepsia 2004; 45:1035-42. [PMID: 15329066 DOI: 10.1111/j.0013-9580.2004.69903.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To evaluate the effects of sex and estrus cycle on biphasic anticonvulsant and proconvulsant modulation of seizure threshold by morphine. METHODS The threshold for the clonic seizures (CST) induced by acute intravenous administration of gamma-aminobutyric acid (GABA)-antagonist pentylenetetrazole (PTZ) was assessed in male and female mice. Estrus cycle was assessed by vaginal smears. The effect of removing circulating sex hormones was assessed by gonadectomy. RESULTS At baseline, diestrus females had a higher CST compared with males and estrus females. Morphine at lower doses (0.5-3 mg/kg) had a significant anticonvulsant effect in males and estrus females compared with that in vehicle-treated controls, whereas female mice in diestrus phase showed a relative subsensitivity to this effect. Morphine at higher doses (30 and 60 mg/kg) significantly decreased CST in males and diestrus females, with less relative effect in estrus mice. In both phases, morphine exerted stronger effects in males compared with females. Ovariectomy brought the baseline CST to the male level and resulted in significant expression of both phases of morphine effect but did not abolish the sex difference in responsiveness to morphine. CONCLUSIONS The biphasic modulation of seizure threshold is subject to both constitutive sex differences in sensitivity to morphine and hormonal fluctuations during the estrus cycle.
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Affiliation(s)
- Kiarash Riazi
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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Abstract
This review covers beta-phenylethylamines and isoquinoline alkaloids and compounds derived from them, including further products of oxidation, condensation with formaldehyde and rearrangement, some of which do not contain an isoquinoline system, together with naphthylisoquinoline alkaloids, which have a different biogenetic origin. The occurrence of the alkaloids, with the structures of new bases, together with their reactions, syntheses and biological activities are reported. The literature from July 2001 to June 2002 is reviewed, with 581 references cited.
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Abstract
This paper is the twenty-fourth installment of the annual review of research concerning the opiate system. It summarizes papers published during 2001 that studied the behavioral effects of the opiate peptides and antagonists. The particular topics covered this year include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology(Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
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Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
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Abstract
Sex differences in the experience of clinical and experimental pain have been reported. However, the neurobiological sources underlying the variability in pain responses between sexes have not been adequately explored, especially in humans. The endogenous opioid neurotransmitters and mu-opioid receptors are centrally implicated in responses to stress, in the suppression of pain, and in the action of opiate analgesic drugs. Here we examined sex differences in the activation of the mu-opioid system in response to an intensity-controlled sustained deep-tissue pain challenge with positron emission tomography and a mu-opioid receptor-selective radiotracer. Twenty-eight young healthy volunteers (14 men and 14 women) were studied during saline control and pain conditions using a double-blind, randomized, and counterbalanced design. Women were scanned during the early follicular phase of their menstrual cycles after ovulatory cycles. Significant sex differences in the regional activation of the mu-opioid system in response to sustained pain were detected compared with saline controls. Men demonstrated larger magnitudes of mu-opioid system activation than women in the anterior thalamus, ventral basal ganglia, and amygdala. Conversely, women demonstrated reductions in the basal state of activation of the mu-opioid system during pain in the nucleus accumbens, an area previously associated with hyperalgesic responses to the blockade of opioid receptors in experimental animals. These data demonstrate that at matched levels of pain intensity, men and women during their follicular phase differ in the magnitude and direction of response of the mu-opioid system in distinct brain nuclei.
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