Homer expression in the hippocampus of an animal model of attention-deficit/hyperactivity disorder.

Abstract

Attention-deficit/hyperactivity disorder (ADHD) is a pervasive neurobehavioral disorder. We previously demonstrated differential expression of some isoforms of Homer, a family of scaffolding proteins localized to the postsynaptic density of glutamatergic excitatory synapses, in the spontaneous hypertensive rat (SHR), which is the most frequently used animal model of ADHD. Since these changes were observed in the prefrontal cortex (PFC), a critical structure in ADHD, it was hypothesized that these Homer isoforms may play a role in ADHD. The present study aimed to extend these findings to the hippocampus, which has direct connections to the PFC and subserves attention and cognition, two functions that are disturbed in ADHD. Hippocampal mRNA and protein expression of several Homer isoforms were investigated in both SHR and control Wistar-Kyoto (WKY) rats using reverse transcription-polymerase chain reaction and Western blotting, respectively. Both mRNA and protein for Homer 1a and Homer 2a/b, but not Homer 1b/c, were expressed at significantly lower levels in the hippocampus of SHR compared to WKY rats. The effects of methylphenidate (MPH) on spatial learning and memory in SHRs were also examined using the Morris water maze and on hippocampal expression of Homer isoforms. MPH improved spatial learning and memory and up-regulated hippocampal expression of Homer 1a and Homer 2a/b, but not Homer 1b/c, in SHRs. The animal model of ADHD may have altered expression of Homer 1a and Homer 2a/b in the hippocampus, in addition to the PFC. Future studies will focus on elucidating the specific mechanisms of Homer 1a and Homer 2a/b in ADHD.

• Authors: Qin Hong, Yan-Ping Wang, Min Zhang, Xiao-Qin Pan, Mei Guo, Fei Li, Mei-Ling Tong, Rong-Hua Chen, Xi-Rong Guo, Xia Chi
• Journal: Molecular medicine reports (Mol Med Rep) 2011 Jul-Aug Vol. 4 Issue 4 Pg. 705-12 ISSN: 1791-3004 [Electronic] Greece
• PMID: 21523321 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carrier Proteins
• Dopamine Uptake Inhibitors
• Homer Scaffolding Proteins
• Protein Isoforms
• RNA, Messenger
• Methylphenidate

Topics

• Animals
• Attention Deficit Disorder with Hyperactivity (drug therapy, metabolism)
• Carrier Proteins (genetics, metabolism)
• Disease Models, Animal
• Dopamine Uptake Inhibitors (therapeutic use)
• Hippocampus (metabolism)
• Homer Scaffolding Proteins
• Learning (drug effects)
• Memory (drug effects)
• Methylphenidate (therapeutic use)
• Protein Isoforms (genetics, metabolism)
• RNA, Messenger (metabolism)
• Rats
• Rats, Inbred SHR
• Rats, Inbred WKY