Early weaning results in less active behaviour, accompanied by lower 5-HT1A and higher 5-HT2A receptor mRNA expression in specific brain regions of female pigs

BEH Sumner, RB D'Eath, MJ Farnworth, S Robson, JA Russell, AB Lawrence, S Jarvis

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

In rodents and humans stressful events in early life e.g. maternal deprivation, can increase sensitivity to stress in later life. Humans may become more susceptible to mood disorders, e.g. depression. In livestock species, such as pigs, early weaning is a form of maternal deprivation. We investigated behavioural consequences in 99 female pigs weaned at three different ages (12, 21 and 42 days; d12, d21, d42). Pigs were habituated to an open field arena over 6 days before being given 5-min open-field tests over three subsequent days (days 77–79). Early-weaned pigs (d12) showed behavioural inhibition (reduced vocalisations and lower activity) compared with later-weaned pigs, although in all groups these measures declined over the three tests, so this treatment difference might reflect more rapid habituation to the test in d12 pigs. Long-term effects on mood-related 5-HT receptor subtypes were measured in the brain at 90 days in a random sample of the d12 (n = 8) and d42 pigs (n = 8), using 3H-ligand-binding and autoradiography and in situ hybridisation histochemistry. There were no differences between weaning ages in binding of 3H-8-OH-DPAT (5-HT1A receptor agonist) or of 3H-ketanserin (5-HT2A receptor antagonist) to any brain region studied. In d12 pigs, 5-HT1A receptor mRNA expression per unit area was 29%, 63%, 52% and 64% lower than in d42 pigs in the parvocellular PVN, amygdala and hippocampal dentate gyrus and pyramidal cell layer, respectively. The ratio of expression per cell to expressing cells per unit area was also lower, by 31%, in the pars horizontalis of the PVN in d12 pigs. Conversely, 5-HT2A receptor mRNA was expressed at a 25% and 28% higher density per unit area in the amygdala and pyramidal cell layer of the hippocampus, respectively, in these d12 pigs. In individual pigs, across brain regions, 5-HT1A receptor mRNA data were 70–79% correlated with binding data but no correlation was found for 5-HT2A data, suggesting different regulatory mechanisms. The behavioural and neurobiological responses to early weaning might represent either dysfunction or adaptation. Further investigation is required.
Original languageEnglish
Pages (from-to)1077 - 1092
Number of pages16
JournalPsychoneuroendocrinology
Volume33
Issue number8
Publication statusFirst published - 2008

Fingerprint

early weaning
brain
receptors
swine
amygdala
emotions
cells
autoradiography
testing
histochemistry
hippocampus
vocalization
in situ hybridization
agonists
long term effects
antagonists
weaning
rodents
livestock

Bibliographical note

62100062
wp2.4

Keywords

  • Behaviour
  • Depression
  • Early weaning
  • Maternal deprivation
  • Open-field test
  • Pig
  • Serotonin
  • Swine

Cite this

@article{461f4ac921ea49658877d7339d39d224,
title = "Early weaning results in less active behaviour, accompanied by lower 5-HT1A and higher 5-HT2A receptor mRNA expression in specific brain regions of female pigs",
abstract = "In rodents and humans stressful events in early life e.g. maternal deprivation, can increase sensitivity to stress in later life. Humans may become more susceptible to mood disorders, e.g. depression. In livestock species, such as pigs, early weaning is a form of maternal deprivation. We investigated behavioural consequences in 99 female pigs weaned at three different ages (12, 21 and 42 days; d12, d21, d42). Pigs were habituated to an open field arena over 6 days before being given 5-min open-field tests over three subsequent days (days 77–79). Early-weaned pigs (d12) showed behavioural inhibition (reduced vocalisations and lower activity) compared with later-weaned pigs, although in all groups these measures declined over the three tests, so this treatment difference might reflect more rapid habituation to the test in d12 pigs. Long-term effects on mood-related 5-HT receptor subtypes were measured in the brain at 90 days in a random sample of the d12 (n = 8) and d42 pigs (n = 8), using 3H-ligand-binding and autoradiography and in situ hybridisation histochemistry. There were no differences between weaning ages in binding of 3H-8-OH-DPAT (5-HT1A receptor agonist) or of 3H-ketanserin (5-HT2A receptor antagonist) to any brain region studied. In d12 pigs, 5-HT1A receptor mRNA expression per unit area was 29{\%}, 63{\%}, 52{\%} and 64{\%} lower than in d42 pigs in the parvocellular PVN, amygdala and hippocampal dentate gyrus and pyramidal cell layer, respectively. The ratio of expression per cell to expressing cells per unit area was also lower, by 31{\%}, in the pars horizontalis of the PVN in d12 pigs. Conversely, 5-HT2A receptor mRNA was expressed at a 25{\%} and 28{\%} higher density per unit area in the amygdala and pyramidal cell layer of the hippocampus, respectively, in these d12 pigs. In individual pigs, across brain regions, 5-HT1A receptor mRNA data were 70–79{\%} correlated with binding data but no correlation was found for 5-HT2A data, suggesting different regulatory mechanisms. The behavioural and neurobiological responses to early weaning might represent either dysfunction or adaptation. Further investigation is required.",
keywords = "Behaviour, Depression, Early weaning, Maternal deprivation, Open-field test, Pig, Serotonin, Swine",
author = "BEH Sumner and RB D'Eath and MJ Farnworth and S Robson and JA Russell and AB Lawrence and S Jarvis",
note = "62100062 wp2.4",
year = "2008",
language = "English",
volume = "33",
pages = "1077 -- 1092",
journal = "Psychoneuroendocrinology",
issn = "0306-4530",
publisher = "Elsevier Limited",
number = "8",

}

Early weaning results in less active behaviour, accompanied by lower 5-HT1A and higher 5-HT2A receptor mRNA expression in specific brain regions of female pigs. / Sumner, BEH; D'Eath, RB; Farnworth, MJ; Robson, S; Russell, JA; Lawrence, AB; Jarvis, S.

In: Psychoneuroendocrinology, Vol. 33, No. 8, 2008, p. 1077 - 1092.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Early weaning results in less active behaviour, accompanied by lower 5-HT1A and higher 5-HT2A receptor mRNA expression in specific brain regions of female pigs

AU - Sumner, BEH

AU - D'Eath, RB

AU - Farnworth, MJ

AU - Robson, S

AU - Russell, JA

AU - Lawrence, AB

AU - Jarvis, S

N1 - 62100062 wp2.4

PY - 2008

Y1 - 2008

N2 - In rodents and humans stressful events in early life e.g. maternal deprivation, can increase sensitivity to stress in later life. Humans may become more susceptible to mood disorders, e.g. depression. In livestock species, such as pigs, early weaning is a form of maternal deprivation. We investigated behavioural consequences in 99 female pigs weaned at three different ages (12, 21 and 42 days; d12, d21, d42). Pigs were habituated to an open field arena over 6 days before being given 5-min open-field tests over three subsequent days (days 77–79). Early-weaned pigs (d12) showed behavioural inhibition (reduced vocalisations and lower activity) compared with later-weaned pigs, although in all groups these measures declined over the three tests, so this treatment difference might reflect more rapid habituation to the test in d12 pigs. Long-term effects on mood-related 5-HT receptor subtypes were measured in the brain at 90 days in a random sample of the d12 (n = 8) and d42 pigs (n = 8), using 3H-ligand-binding and autoradiography and in situ hybridisation histochemistry. There were no differences between weaning ages in binding of 3H-8-OH-DPAT (5-HT1A receptor agonist) or of 3H-ketanserin (5-HT2A receptor antagonist) to any brain region studied. In d12 pigs, 5-HT1A receptor mRNA expression per unit area was 29%, 63%, 52% and 64% lower than in d42 pigs in the parvocellular PVN, amygdala and hippocampal dentate gyrus and pyramidal cell layer, respectively. The ratio of expression per cell to expressing cells per unit area was also lower, by 31%, in the pars horizontalis of the PVN in d12 pigs. Conversely, 5-HT2A receptor mRNA was expressed at a 25% and 28% higher density per unit area in the amygdala and pyramidal cell layer of the hippocampus, respectively, in these d12 pigs. In individual pigs, across brain regions, 5-HT1A receptor mRNA data were 70–79% correlated with binding data but no correlation was found for 5-HT2A data, suggesting different regulatory mechanisms. The behavioural and neurobiological responses to early weaning might represent either dysfunction or adaptation. Further investigation is required.

AB - In rodents and humans stressful events in early life e.g. maternal deprivation, can increase sensitivity to stress in later life. Humans may become more susceptible to mood disorders, e.g. depression. In livestock species, such as pigs, early weaning is a form of maternal deprivation. We investigated behavioural consequences in 99 female pigs weaned at three different ages (12, 21 and 42 days; d12, d21, d42). Pigs were habituated to an open field arena over 6 days before being given 5-min open-field tests over three subsequent days (days 77–79). Early-weaned pigs (d12) showed behavioural inhibition (reduced vocalisations and lower activity) compared with later-weaned pigs, although in all groups these measures declined over the three tests, so this treatment difference might reflect more rapid habituation to the test in d12 pigs. Long-term effects on mood-related 5-HT receptor subtypes were measured in the brain at 90 days in a random sample of the d12 (n = 8) and d42 pigs (n = 8), using 3H-ligand-binding and autoradiography and in situ hybridisation histochemistry. There were no differences between weaning ages in binding of 3H-8-OH-DPAT (5-HT1A receptor agonist) or of 3H-ketanserin (5-HT2A receptor antagonist) to any brain region studied. In d12 pigs, 5-HT1A receptor mRNA expression per unit area was 29%, 63%, 52% and 64% lower than in d42 pigs in the parvocellular PVN, amygdala and hippocampal dentate gyrus and pyramidal cell layer, respectively. The ratio of expression per cell to expressing cells per unit area was also lower, by 31%, in the pars horizontalis of the PVN in d12 pigs. Conversely, 5-HT2A receptor mRNA was expressed at a 25% and 28% higher density per unit area in the amygdala and pyramidal cell layer of the hippocampus, respectively, in these d12 pigs. In individual pigs, across brain regions, 5-HT1A receptor mRNA data were 70–79% correlated with binding data but no correlation was found for 5-HT2A data, suggesting different regulatory mechanisms. The behavioural and neurobiological responses to early weaning might represent either dysfunction or adaptation. Further investigation is required.

KW - Behaviour

KW - Depression

KW - Early weaning

KW - Maternal deprivation

KW - Open-field test

KW - Pig

KW - Serotonin

KW - Swine

M3 - Article

VL - 33

SP - 1077

EP - 1092

JO - Psychoneuroendocrinology

JF - Psychoneuroendocrinology

SN - 0306-4530

IS - 8

ER -