Expression of tyramine β – hydroxylase and tyrosine hydroxylase genes in response to odor valence in the brain of the honey bee, Apis mellifera

In mammals, approach or avoidance behaviors to rewarding or aversive stimuli are reinforced via specific neural pathways. In invertebrates, less is understood about the mechanisms and brain regions involved in mediating reward and aversion. Invertebrate research suggests octopamine (OA) signaling mediates the positive reinforcement of food rewards (Hammer 1993, 1997; Menzel and Muller 1996; Schwärzel et al., 2003) and dopamine (DA) modulates aversive learning (Schwärzel et al. 2003; Reimensperger et al., 2005; Claridge-Chang et al., 2009; Barron et al., 2010; Vergoz et al., 2007a,b). It is unknown if subsets of octopaminergic or dopaminergic neurons in honey bees are differentially utilized after memory retrieval in response to differences in hedonic valence. This study addresses the hypothesis that specific regions of the honey bee brain differentially respond after recalling a positive or negative memory by mapping the expression of genes that encode the rate limiting enzymes in OA and DA synthesis, tyramine β – hydroxylase (tbh) and tyrosine hydroxylase (th), respectively, in response to conditioned odor valence. Populations of tbh- and th-expressing neurons in 6 and 4 locations of the bee brain, respectively, were measured. I discovered ventrally positioned th-expressing unpaired medial neurons in the suboesophageal ganglion (SOG) never before reported in the honey bee. I also found increases in both the proportion of individuals with, and relative intensity of, ventral paired median tbh-expressing neurons in the posterior third segment of the SOG. Results suggest that the posterior region of the SOG may be important in the response to food rewards and support the hypothesis that subsets of neurons differentially respond after memory retrieval in response to hedonic valence in the honey bee.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Entomology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2013

Author dc:creator

• McGill, Tara

Contributors dc:contributor

• Robinson, Gene E.

• reward
• tyramine β – hydroxylase
• tyrosine hydroxylase
• in situ hybridization
• honey bee

Statement dc:rights

• Copyright 2012 Tara McGill

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/42289

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/42289