Energy balance is regulated, in part, by the orexigenic signaling pathways of the vagus nerve. Fasting-induced modifications in the expression of orexigenic signaling systems have been observed in vagal afferents of lean animals. Altered basalcannabinoid (CB₁) receptor expression in the nodose ganglia in obesity has been reported. Whether altered body weight or a high fat diet modifies independent or additive changes in CB₁ expression is unknown. We investigated the expression of CB₁ and orexin 1 receptor (OX-1R) in the nodose ganglia of rats fed ad libitum or food deprived (24h), maintained on low or high fat diets (HFD), with differing body weights. Male Wistar rats were fed chow or HFD (diet-induced obese: DIO or diet-resistant: DR) or were body weight matched to the DR group but fed chow (wmDR). CB₁ and OX-1R immunoreactivity were investigated and CB₁mRNA density was determined using in situ hybridization. CB₁ immunoreactivity was measured in fasted rats after sulfated cholecystokinin octapeptide (CCK8s) administration. In chow rats, fasting did not modify the level of CB₁ mRNA. More CB₁immunoreactive cells were measured in fed DIO, DR and wmDR rats than chow rats; levels increased after fasting in chow and wmDR rats but not in DIO or DR rats. In HFD fasted rats CCK8s did not reduce CB₁ immunoreactivity. OX-1R immunoreactivity was modified by fasting only in DR rats. These data suggest that body weight contributes to the proportion of neurons expressing CB₁ immunoreactivity in the nodose ganglion, while HFD blunts fasting-induced increases, and CCK-induced suppression of, CB₁-immunoreactivity.
© 2013.

PMID:

 

24145047

 

[PubMed – as supplied by publisher]