Changes in mouse mu opioid receptor exon 7/8-like immunoreactivity following food restriction and food deprivation in rats

Maria M. Hadjimarkou, Catherine Abbadie, Lora J. Kasselman, Ying Xian Pan, Gavril W. Pasternak, Richard J. Bodnar

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Opioid agonists and antagonists respectively increase and decrease food intake. That selective mu opioid antagonists are more effective than antisense probes directed against the mu opioid receptor (MOR-1) gene in reducing deprivation-induced feeding suggests a role for isoforms. Both food restriction and deprivation alter protein and mRNA levels of opioid peptides and receptors. Antisera directed against Exon 4 of the MOR-1-like immunoreactivity (LI) (Exon 4) clone or directed against mouse Exons 7/8 (mE7/8-LI) revealed high levels of immunoreactivity in brain nuclei related to feeding behavior. Therefore, the present study assessed MOR-1LI and mE7/8-LI in hypothalamic and extrahypothalamic sites in rats exposed to ad libitum feeding, food restriction (2, 7, 14 days), or food deprivation (24, 48 h). MOR-1-LI displayed robust reactivity, but was insensitive to food restriction or deprivation. mE7/8-LI, both in terms of cell counts and relative optical density, was significantly and selectively increased in the dorsal and ventral parvocellular subdivisions of the hypothalamic paraventricular nucleus in food-restricted (14 days) rats, but all other restriction or deprivation regimens were ineffective in other hypothalamic nuclei. In contrast, significant and site-specific decreases in relative optical density in the rostral part of the nucleus tractus solitarius (NTS) were observed in food-restricted (2, 7 days) or food-deprived (24, 48 h) animals, but these regimens were ineffective in the other extrahypothalamic sites. This study indicates the sensitivity of this mE7/8-LI probe in the hypothalamic parvocellular paraventricular nucleus and rostral NTS to food restriction and deprivation in rats.

Original languageEnglish
Pages (from-to)585-597
Number of pages13
Issue number7
StatePublished - Jul 2009
Externally publishedYes


  • Nucleus tractus solitarius
  • Opioids
  • Paraventricular hypothalamic nucleus


Dive into the research topics of 'Changes in mouse mu opioid receptor exon 7/8-like immunoreactivity following food restriction and food deprivation in rats'. Together they form a unique fingerprint.

Cite this