Dopamine participating in locomotor regulation of the German cockroach, Blattella germanica L. (Dictyoptera: Blattellidae)

• Main Authors: Tien-Hsien Lin, 林典憲
• Other Authors: How-Jing Lee
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/g3h2r9

碩士 === 國立臺灣大學 === 昆蟲學研究所 === 106 === Circadian clock is a 24-hour internal clock existing in almost every organism on Earth. The locomotor circadian rhythm of virgin female adults of the German cockroach is masked by increasing mate-finding activity and even-distributed throughout the day during sexually receptive period, even though male adults still cofine their mate-finding activity at night. Since dopamine (DA) is a neurotransmitter involving in signal transduction from brain to muscle, it serves as a potential masking factor on locomotor circadian rhythm. Furthermore, it plays multiple roles in the regulation of learning, feeding, locomotion and reproduction in insects. In the synthesized cascade of dopamine, tyrosine hydroxylase and dopa decarboxylase are the essential enzymes, and circadian rhythmicity of their mRNA expression levels are consistent with locomotor activity patterns of male and female adults. The mRNA expression level of tyrosine hydroxylase and dopa decarboxylase in male adults displayed circadian rhythm, but none of them displayed circadian rhythm in virgin female adults. Moreover, tyrosine hydroxylase and dopa decarboxylase mRNA expression levels had no significant difference between sexually and non-sexually receptive female adults’ ovary and dopamine receptor 1 and receptor 2 mRNA were not detected in the non-sexually receptive female adults’ ovary. The effect of extra dopamine and antagonist (cis(Z)-flupenthixol) on locomotor activities of male and female adults only last for one day. In addition, extra dopamine and antagonist injection did not alter the expression of circadian rhythm in both male and female adults regardless the changes in total locomotor activities. These results suggest that dopamine does participate in downstream regulation of locomotion without affecting the circadian clock.