Location: Bowdoin / Coastal Studies Center / Student Research / Summer 2011 / Anirudh Sreekrishnan '12

Coastal Studies Center

Anirudh Sreekrishnan '12

Advisor: Patsy Dickinson Award: Doherty Fellowship
Project: The effects of molt hormone (20-Hydroxyecdysone) on the modulation by histamine in the cardiac ganlion of the Homarus americanus

One characteristic of an effective control system is its ability to respond and adapt to change. Anirudh Even the cardiac system, with its cyclic pattern, must be able to integrate cues and react accordingly. Ranging from environmental to hormonal, these cues along with the intrinsic properties of the heart are responsible for modulating circulatory flow throughout the body.
The cardiac ganglion of Homarus americanus is controlled by a central pattern generator, which is a neuronal circuit responsible for maintaining rhythmic patterns like breathing and walking. This specific central pattern generator is composed of 9 cells that establish a rhythmic pattern of action potentials, controlling the beating of the heart. With its small number of cells, the cardiac ganglion has become an easy model system to dissect and analyze.

Since histamine has been implicated in human cardiovascular functions and possibly linked to the molt cycle of lobsters, it seems like a candidate to study in the cardiac ganglion. The hormone responsible for molting is 20-hydroxyecdysone (20-HE), which has already been shown to have a connection to changes in behavior. Along with modulating the molt cycle, 20-HE could be affecting histamine as proposed by research in the stomatogastric system. This modulation could be done via direct effect on histamine expression or on the histamine receptor. Further work in this area can provide greater insight into the connection between the molt cycle and histamine as well as how hormone-hormone interactions occur.

To test this hypothesis, it is important to examine whether the effect of histamine on the whole heart depends on the lobster’s molt stage. A transducer will be attached to the anterior artery to measure tension and stretch, while varying concentrations of histamine are profused through the tubing. Based on the hypothesis, I would expect to find that the effects of histamine vary depending on the lobster’s molt stage. This research can be taken a step further, by looking at only the isolated cardiac ganglion in order to get a sense of the mechanism of this process. 


Pecha Kucha

These presentations are in PechaKucha format. PechaKucha is Japanese for ‘chit-chat’. It is a presentation methodology devised in 2003 in which 20 slides are shown for 20 seconds each. The slides auto advance to keep the presentations concise and quick paced. Each presentation is (about) 6 minutes and 40 seconds long.
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