Aggression-modifying pheromones:Pheromone Resources

Aggression-modifying pheromones:

Alarm pheromone released from the face modifies behavior and that from the anal area induces autonomic stress responses in recipients (Kiyokawa et al., 2004a). The pattern and intensity of changes in behavioral parameters induced by the whisker pad odor were almost identical to those evoked by alarm pheromones released from conscious male rats given foot shocks (Kiyokawa et al., 2004b).

 The preputial glands of house mice express the gene for the fifth melanocortin receptor (MC5-R) and are a primary source of urinary pheromones involved in inter-male aggression. A `resident-intruder' behavioral model was used to compare the responses of resident males to urine from mice with an engineered disruption of the fifth melanocortin receptor (MC5-RKO) with residents' responses to urine from wild-type mice (WT) in the preputial glands of male house mice causes excretion of urinary pheromones that delay aggressive responses by other males (Caldwell and  Lepri,2002).

Mice lacking the melanocortin-5 receptor (MC5R) exhibit decreased sensitivity to the stimulatory effects of systemic melanocortin injections on aggressive behavior. Because the pheromone-producing preputial gland expresses the MC5R, deficiency decreases preputial and urine levels of the sex pheromones, alpha- and beta-farnesene, relative to wild-type mice. The farnesenes potently stimulate aggression in mice. Moreover, farnesene-stimulated aggression is reduced in MC5R-deficient mice, relative to wild-type mice (Morgan et al.,2004a).

The endogenous melanocortin, alpha-melanocyte-stimulating hormone (alpha-MSH), is a neurohormone secreted by the neurointermediate lobe of the pituitary. Alpha-MSH promotes intermale aggression in mice by influencing pheromone secretion, but the role of specific melanocortin receptors has not been determined.  In heterotypic pairs assessed in the social interaction test (SIT), MC5R-deficient mice exhibited less aggressive behavior and more defensive behavior than their wild-type opponents. Urine from MC5R deficient mice stimulated more aggression than did urine from wild-type mice (Morgan et al.,2004b).

The phenomena of hormone-aggression correlations in a wide range of species, but this is not meant to imply the existence of genes for aggression. It is likely that similar strategies will lead to analogous hormone-aggression relationships even in diverse species. One should emphasize (as in Brain, Haug, & Kamis, in press) that different models of aggression generate radically different views of the relationships between hormones and this behavior even within the same species (Brain, 1980,1983). 

References:

Brain, P. F. 1980.Adaptive Aspects of Hormonal Correlates of Attack and Defence in. Adaptive Capabilities of the Nervous System: Proceedings of the 11th International Summer School of Brain Research, 53, 391.

Brain, P. F. 1983.Pituitary-gonadal influences on social aggression. InHormones and aggressive behavior (pp. 3-25). Springer US.

Caldwell, H. K. and  Lepri, J. J. 2002.Disruption of the fifth melanocortin receptor alters the urinary excretion of aggression-modifying pheromones in male house mice. Chemical senses, 27(1):91-94.

Kiyokawa,Y.,Kikusui, T., Takeuch,Y. and Mori, Y.2004b.Modulatory role of testosterone in alarm pheromone release by male rats. Horm. Behav., in press.

Kiyokawa,Y.,Takefumi Kikusui,Yukari Takeuchi and Yuji Mori.2004a.Alarm Pheromones with Different Functions are Released from Different Regions of the Body Surface of Male Rats. Chem. Senses., 29:35-40.

Morgan, C., Thomas, R. E. and  Cone, R. D.2004b.Melanocortin-5 receptor deficiency promotes defensive behavior in male mice. Hormones and behavior,45(1):58-63.

Morgan, C., Thomas, R. E., Ma, W., Novotny, M. V. and  Cone, R. D. 2004a. Melanocortin-5 receptor deficiency reduces a pheromonal signal for aggression in male mice. Chemical senses, 29(2):111-115.