How Taste And Odor Perception Is Altered In Pregnancy

It’s well known that perception of different tastes and smells and tastes can change when a woman is pregnant. But did you know this is also true for flies?

Not only that, but just how these changes are triggered is not really known, either for mammals or insects. But now, scientists from the Max Planck Institute of Neurobiology in Martinsried have shown that the concentration of a certain receptor increases in the sensory organs of pregnant fruit fly females.

Because of this, the taste and odor of important nutrients, known as polyamines, are processed differently in the brain. Pregnant flies favor nutrition that is rich in polyamines and so increase their reproductive success.

Ilona Grunwald Kadow, Research Group Leader at the Max Planck Institute of Neurobiology, said:

“We wanted to find out whether and how expectant mothers can sense the nutrients they need.”

uterus of the female fly

Part of the reproductive system with the uterus of the female fly. Credit: MPI of Neurobiology/ Friedrich

Pregnancy has a huge impact on a mother’s body. To give the best nutrition for the developing offspring, her nutrition must be adapted to the altered requirements.

Polyamines

Polyamines can be made by both the body itself and by intestinal bacteria, but some of the required polyamines must be obtained from food.

With advancing age, the consumption of polyamines through food increases in importance, as the body’s own production declines. Polyamines play a role in numerous cell processes and a polyamine deficiency can have a negative impact on health, cognition, reproduction and life expectancy.

chemosensory neurons

SPR/MIP signaling in chemosensory neurons adjusts female preference behavior upon mating. PLoS Biol

An excess of polyamines can also be harmful, however. The intake of polyamines therefore need to be adapted to the body’s current needs. Neurobiologists at Max Planck demonstrated that, after mating, female fruit flies show a preference for food with a high polyamine content.

Behavioural studies and physiological tests revealed that the change in the appeal of polyamines to flies before and after mating is triggered by a neuropeptide receptor known as the sex peptide receptor (SPR) and its neuropeptide binding partner.

“It was already known that the SPR boosts egg production in mated flies,” explains Ashiq Hussain, one of two first authors. “But we were surprised to discover that the SPR also regulates the activity of the sensory neurons that recognize the taste and smell of polyamines.”

Many more sex peptide receptors are integrated into the surfaces of the chemosensory neurons in pregnant females. This increase in neuropeptide signalling modifies the reaction of the sensory neurons to the odour and taste. The thereby intensified odour and taste perception therefore occurs at a very early stage in the nervous system.

“Because smell and taste are processed in a similar way in insects and mammals, a corresponding mechanism in humans could also ensure an optimal nutritional supply for the developing life,” said Habibe Üc̗punar, second first author.

Study: Neuropeptides Modulate Female Chemosensory Processing upon Mating in Drosophila