Grooming and related behaviors

Behavioral and pharmacological research continues to play a crucial role in modern neuroscience, often spearheading new and innovative techniques and models that further our understanding of the intricate workings of the nervous system. This is particularly evident in the arena of mental health research where, with the help of animal models and novel genetic or pharmacological treatments, new insights and theories are evolving to conceptualize more accurately common brain disorders such as anxiety, depression, obsessive–compulsive disorder (OCD), and schizophrenia.

These advances are allowing for an unprecedented examination of the heritable and environmental factors that contribute to disease pathogenesis. However, although there has been marked progress, the biological substrates of many of these disorders remain unclear. To establish a more concrete understanding of these disorders, a careful dissection of experimental phenotypes must be pursued. In this way, every aspect of behavior is a potentially fruitful source of experimental data that can provide clues to the contributing mechanisms.

One important example of such a behavior is grooming. Grooming is a very highly represented behavior in many animals, comprising a large proportion of their waking time. It serves an incredibly diverse range of purposes in the life of the animal from chemocommunication to basic hygiene. It is a natural behavior, yet it can be induced as part of an experimental procedure and has been shown to be sensitive to stress and bidirectionally sensitive to anxiolytic and anxiogenic drugs in rodents, making it an ideal focal point for high-throughput behavioral studies.

ABSTRACT

There is growing clinical evidence that many psychiatric illnesses have overlapping genetic mechanisms. Understanding these mechanisms is important to the improvement of psychiatric treatment and preventions of the disorders, and animal genetic models continue to be a critical avenue of research towards these ends. As serotonin is a key neurotransmitter with important roles in normal behavioral processes and has been implicated in the pathogenesis of psychopathological conditions such as depression, anxiety, and addiction, it is a prime target for investigation in behavioral neurogenetics. The serotonin transporter (SERT) is a key brain protein that regulates the amount of serotonin that can activate the receptor. It is becoming evident that SERT interacts with brain-derived neurotrophic factor (BDNF), an important modulator of dopaminergic, cholinergic, and serotonergic neurons, which has been linked to memory function, activity, eating behavior, depression, and anxiety. The pivotal roles played by these two brain molecules have resulted in the development of numerous mutant animal models that have reduced function of SERT, BDNF, or both. Interestingly, SERT × BDNF mutant mice show numerous different behavioral phenotypes that are distinct from either SERT mutants or BDNF mutants alone, displaying phenotypes that are highly relevant to human clinical scenarios and bringing them added validity. This chapter will provide data from numerous experiments utilizing these rodent models and will explain their relevance and validity for research into the genetics of neuropsychiatric disorders.