What may result from too little serotonin?

Serotonin is a crucial neurotransmitter that plays an essential role in various physiological functions, including mood regulation, digestion, and overall gastrointestinal motility. When serotonin levels are insufficient, it can lead to hypomotility, which refers to decreased movement in the gastrointestinal tract. This decreased motility can result in constipation, as the intestines are not effectively moving waste through the digestive system.

The connection between serotonin and gastrointestinal function is well-established, as the majority of the body's serotonin is found in the gut, where it regulates bowel movements. Therefore, a deficiency in serotonin can impair normal digestive processes, resulting in symptoms like constipation and reduced motility. This understanding helps to clarify why too little serotonin can lead to hypomotility and constipation in affected individuals, making this the correct answer.