Cocaine- and amphetamine related transcript (CART) and anxiety

CART is a neuropeptide that appears to play an important role in a variety of physiological processes. The major research focus into the function of CART peptide has been on feeding behavior, modulation of mesolimbic dopamine, and actions of psychostimulant drugs. The neuroanatomic expression profile of CART does however suggest other functions as well, and its presence within the limbic system points to a possible role in emotionality. There are now several published reports which describe a new role for CART as a mediator of anxiety-like behaviors in rodents. This review will summarize these findings and speculate on the mechanisms by which CART might be involved in the modulation of these behaviors. We will also consider what future studies need to be done to further clarify the role of this peptide in anxiety.     

Thyrotropin Releasing Hormone (TRH) in goldfish (Carassius auratus): role in the regulation of feeding and locomotor behaviors and interactions with the orexin system and cocaine- and amphetamine regulated transcript (CART)

TRH is a peptide produced by the hypothalamus which major function in mammals is the regulation of TSH secretion by the pituitary. In fish, TRH does not appear to affect TSH secretion, suggesting that it might regulate other functions. In this study, we assessed the effects of central (intracerebroventricular, icv) injections of TRH on feeding and locomotor behavior in goldfish. TRH at 10 and 100 ng/g, but not 1 ng/g, significantly increased feeding and locomotor behaviors, as indicated by an increase in food intake and in the number of total feeding acts as compared to saline-injected fish. In order to assess possible interactions between TRH and other appetite regulators, we examined the effects of icv injections of TRH on the hypothalamic expression of orexin, orexin receptor and CART. The mRNA expression levels of all three peptides were significantly increased in fish injected with TRH at 100 ng/g as compared to saline-injected fish. Fasting increased TRH, orexin, and orexin receptor hypothalamic mRNA levels and decreased CART hypothalamic mRNA levels. Our results suggest that TRH is involved in the regulation of feeding/locomotor activity in goldfish and that this action is associated with a stimulation of both the orexin and CART systems.