Connexin 36 as a Regulator of Consummatory Behaviour

Abstract

Gap junctions enable metabolic and electrical coupling of adjacent cells. Connexin 36 (Cx36) is a gap junction protein found predominantly in mammalian neurons. Because Cx36 is expressed in many areas involved in the regulation of food intake, its role in this was explored. I therefore investigated whether genetic knockout (KO) of Cx36 affects the intake of various sweet tastants during long-term concurrent feeding with bland chow, and affects intake of sweet tastants alone during short-term feeding. In addition, I investigated whether a conditioned taste aversion (CTA) would be altered by KO of Cx36. LiCl was injected intraperitoneally (IP) following exposure to a sweet novel tastant. 48 hours later mice were given a two-bottle preference test of tastant vs. water to determine aversive response. Cx36 KO animals consumed less sweet palatable tastants and consumed more bland chow during long-term intake. Sweet tastant consumption was similarly increased during short-term intake. This is suggestive of Cx36 being implicated in both reward mediated and homeostatic regulation. A CTA was enhanced by the KO of Cx36, potentially due to its role in the reward system, and/or an effect of hypothalamic endocrine nuclei implicated in the acquisition of a CTA. In summary, Cx36 may be involved in reward system response to sweet palatable food consumption, and the magnitude of aversive response. Cx36 may also be implicated in post-ingestive endocrine food intake and aversion regulation.