혼자 공부하면서 생각한 것들을 적어가는 공간입니다.
의견 주고받으면서 같이 공부하실 분은 언제든 환영입니다.
An amygdala circuit that suppresses social engagement
Jeong-Tae Kwon, Changhyeon Ryu, Hyeseung Lee, Alec Sheffield, Jingxuan Fan, Daniel H Cho, Shivani Bigler, Heather A Sullivan, Han Kyung Choe, Ian R Wickersham, Myriam Heiman, Gloria B Choi
PMID: 33790466 DOI: 10.1038/s41586-021-03413-6
Abstract
Innate social behaviours, such as mating and fighting, are fundamental to animal reproduction and survival. However, social engagements can also put an individual at risk. Little is known about the neural mechanisms that enable appropriate risk assessment and the suppression of hazardous social interactions. Here we identify the posteromedial nucleus of the cortical amygdala (COApm) as a locus required for the suppression of male mating when a female mouse is unhealthy. Using anatomical tracing, functional imaging and circuit-level epistatic analyses, we show that suppression of mating with an unhealthy female is mediated by the COApm projections onto the glutamatergic population of the medial amygdalar nucleus (MEA). We further show that the role of the COApm-to-MEA connection in regulating male mating behaviour relies on the neuromodulator thyrotropin-releasing hormone (TRH). TRH is expressed in the COApm, whereas the TRH receptor (TRHR) is found in the postsynaptic MEA glutamatergic neurons. Manipulating neural activity of TRH-expressing neurons in the COApm modulated male mating behaviour. In the MEA, activation of the TRHR pathway by ligand infusion inhibited mating even towards healthy female mice, whereas genetic ablation of TRHR facilitated mating with unhealthy individuals. In summary, we reveal a neural pathway that relies on the neuromodulator TRH to modulate social interactions according to the health status of the reciprocating individual. Individuals must balance the cost of social interactions relative to the benefit, as deficits in the ability to select healthy mates may lead to the spread of disease.
동물과 식물 모두 종족번식을 한다는 근본적인 공통점이 있다. 꽤 오래전에 읽어서 정확히 기억이 나지는 않지만, '이기적 유전자'에서는 이러한 종족번식에 대해 '유전자 보존을 위한 번식'이라고 했었던 것 같다. 표현 방법은 다르지만, 어찌 되었든 둘 다 모두 다음 세대를 위한 행동이라는 점은 동일하다. 이 종족번식을 위해 - 건강한 후 세대를 위해 - 각 집단내에서 다양한 경쟁이 발생하고, 우위를 차지하는 자에게 더 많은 번식의 기회가 돌아간다. 그러면, 어떻게 동물들은 상대방이 건강한 파트너인지 알 수 있을까? 건강한 파트너와 그렇지 못한 파트너를 구분하기 위한 메커니즘이 존재할 테고, 그러면 그 메커니즘은 분명 뇌에 저장되어 있을 것이다. 이 논문은 바로 이런 건강한 파트너를 고르는 것을 가능하게 해주는 뇌의 특정 부분을 발견하였고, 해당 부분이 뇌의 다른 영역과 어떤 관계를 맺고 있는지에 대한 연구 결과를 보여주고 있다.
lipopolysaccharide (LPS): induces bacterial infection
Cortical amygdala (COApm)
Medial amygdalar nucleus (MEA)
Thyrotropin-releasing hormone (TRH)
Taltirelin: TRHR agonist
Figure 1. Bacterial infection (LPS) induced mating behavior changes and involvement of cortical amygdala (COApm)
- a-e: Injection of LPS (or PBS) and behavior changes
- f-g: FOS expression difference between PBS vs. LPS
- h-o: Increased neural activities from COApm by interaction with LPS-female (simple mounting behavior did not change neural activity)
Figure 2. Modulation of COApm and behavior changes
- a-e: Activating COApm decreased mating behavior
- f-h: Activating COApm did not change other motivation/sociability/preference related behavior
- i-m: Inhibition of COApm increased mating behavior
Figure 3. Cell-type specific COApm to MEA projection that mediates mating behavior
- a-e: COApm neurons makes specific synapses onto MEA-Glutamatergic neurons
- f-i: Circuit specific modulation and behavior changes
Figure 4. Involvement of thyrotropin-releasing hormone (TRH) and TRH receptor (TRHR) in mating behavior
- a-b: Expression of Trh mRNA and quantification of Trh+ cells
- c-h: Activation of Trh+ neurons decreased mating behavior
- i, j: Expression pattern of TRHR in MEA and co-expression with either Vglu2 or Vgat
- k-o: Injection of TRHR agonist, taltirelin, into MEA and mating behavior changes.
- p-t: Behavior changed observed with TRHR-conditional-knockout (Trhrfl/fl) animals
