Dopamine affects the level of 20-hydroxyecdysone in Drosophila virilis females

Rescuing the Inhibitory Effect of the Salivary Gland Hypertrophy Virus of Musca domestica on Mating Behavior

Infection with salivary gland hypertrophy virus (MdSGHV) of Musca domestica prevents female flies from accepting copulation attempts by healthy or virus-infected males. This study focused on supplemental hormonal rescue therapy for mating behavior in virus-infected female house flies. The inhibitory effect of the virus on mating behavior in females injected with MdSGHV was reversed by hormonal therapy in the form of octopamine injections, topical application of methoprene, or both therapies combined along with 20-hydroxyecdysone. Infected females whose mating responsiveness had been restored continued to have other viral pathologies associated with infection such as hypertrophy of the salivary glands and a lack of ovarian development.

Stress-related hormones affect carbohydrate metabolism in Drosophila females

A highly conservative insulin signaling pathway, stable work of which is indicated by carbohydrates metabolism, is also known to play an important role in the control of stress resistance. Here we demonstrate that exposure to heat stress leads to a rise in the levels of trehalose and glucose in females of Drosophila melanogaster, but does not affect the expression level of the trehalase (Treh) gene. We have shown that the rise in juvenile hormone (JH) and dopamine decreases levels of both carbohydrates under the normal conditions but brings them to values close to normal following the stress exposure. The data obtained suggest that (a) dopamine and JH involved in the neuroendocrine stress reaction in D. melanogaster also take part in the regulation of carbohydrates metabolism, tending to normalize it after stress; (b) the regulation of trehalose content under stress does not occur at the level of transcription of the degrading enzyme.

Ecdysone signaling regulates the formation of long-term courtship memory in adult Drosophila melanogaster

Improved survival is likely linked to the ability to generate stable memories of significant experiences. Considerable evidence in humans and mammalian model animals shows that steroid hormones, which are released in response to emotionally arousing experiences, have an important role in the consolidation of memories of such events. In insects, ecdysone is the major steroid hormone, and it is well characterized with respect to its essential role in coordinating developmental transitions such as larval molting and metamorphosis. However, the functions of ecdysone in adult physiology remain largely elusive. Here, we show that 20-hydroxyecdysone (20E), the active metabolite of ecdysone that is induced by environmental stimuli in adult Drosophila, has an important role in the formation of long-term memory (LTM). In male flies, the levels of 20E were found to be significantly increased after courtship conditioning, and exogenous administration of 20E either enhanced or suppressed courtship LTM, depending on the timing of its administration. We also found that mutants in which ecdysone signaling is reduced were defective in LTM, and that an elevation of 20E levels was associated with activation of the cAMP response element binding protein (CREB), an essential regulator of LTM formation. Our results demonstrate that the molting steroid hormone ecdysone in adult Drosophila is critical to the evolutionarily conserved strategy that is used for the formation of stable memories. We propose that ecdysone is able to consolidate memories possibly by recapturing molecular and cellular processes that are used for normal neural development.