Effects of beta-funaltrexamine treatment and sexual isolation in the perinatal period on the development of mu-opioid receptors and nociception.
Male and female rats were segregated from birth (sexually isolated animals). Additional litters containing both male and female pups were kept as controls (mixed-housed animals). beta-FNA (5 mg/kg) or water was administered SC at day 0 or day 7 to isolated and mixed-housed animals. The development of mu-opioid receptors and nociceptive responses in the two groups was assessed at day 7 or 14, respectively. Mu-receptor binding was measured in whole brain using (3H) DAGO as a binding ligand and nociception assessed using the tail immersion test. beta-FNA treatment depressed mu-receptors when measured 1 but no 7 days later. However, male and female rats treated at day 0 with beta-FNA had lower brain protein content. Sexual isolation had little effect on mu-receptor number and did not augment the beta-FNA effect. However, isolation increased pain sensitivity in 7-day-old animals and in 14-day-old females. beta-FNA treatment had little effect on nociceptive threshold but reversed the effects of sexual isolation.
de Cabo
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Departamento de Biologia Animal II, Universidad Complutense, Madrid, Spain.
Kitchen
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Kelly
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Viveros
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D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology; D005260:Female; D008297:Male; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017450:Receptors, Opioid, mu / Q000187:drug effects* / Q000502:physiology; D012684:Sensory Thresholds / Q000187:drug effects / Q000502:physiology; D012741:Sexual Maturation / Q000187:drug effects* / Q000502:physiology; D012931:Social Environment; D012934:Social Isolation
D009292:Narcotic Antagonists; D017450:Receptors, Opioid, mu; D009271:Naltrexone; C024524:beta-funaltrexamine