Cortisol Exerts Site‐, Context‐ and Dose‐Dependent Effects on Agonistic Responding in Hamsters

Abstract

Site-, context-and dose-dependent actions of intrahypothalamic cortisol administration on the agonistic behaviors of adult male golden hamsters (n = 128 dyads) were examined. W h e n cortisol-treated animals were tested in paired encounters with aggressive cholesterol-treated opponents, chronic ( 2 2 4 h ) cortisol treatment (1 mm implants) induced significant (P < 0.05) submission in three medial hypothalamic a r e a s (anterior hypothalamic area > medial preoptic area > ventromedial hypothalamus), but aggression in t h e paraventricular nucleus or third ventricle. In contrast, chronic cortisol treatment in the anterior hypothalamic area resulted in high levels of aggression during paired encounters with submissive opponents, and during territorial aggression tests with juvenile male intruders. Acute ( 1 2 0 min) cortisol treatment in the anterior hypothalamic area (100 nl injections) induced significant submission after lo-' M, but significant aggression after M microinjections in paired encounters with aggressive vehicleinjected opponents. These findings suggest glucocorticoid-sensitive mechanisms within the anterior hypothalamus modulate aggressive responding during intrasexual social encounters.Glucocorticoids (GC) are released and have profound effects on brain activity during all behaviorally-aroused circumstances whcIc adaptive responses to environmental stimuli occur (1 -4). Howcver, no evidence of a connection between the neurobiological events underlying hypothalamic-pituitary-adrenal (HPA) axis activation and regulation (5-lo), and the central conttol of agonistic responding exists (1 1 -16).Ri-ain stimulation and lesion studies identified an area within the medial and lateral hypothalamus that participates in 'hypothalamic aggression'. This area consists of a continuous and localized band of cells in the medial preoptic area (MPOA), anterior hypothalamic area (AHA), ventromedial hypothalamus (VMH), and lateral/perifornical hypothalamus in most mammalian species examined (17-22). In rats, electrical stimulation in the AHA, caudal MPOA and rostra1 VMH elicits both aggressive, i.e. bites and attacks (23), and submissive, i.e. escape jump and flight, behaviors (24). GC receptors (25-29) and GC-responsive neurons ( I , 3, 30-32) are found throughout the more medial aspects of this 'hypothalamic aggression area' in rats and hamsters. Systemic and direct administration of GC have complex, e 4 . excitatory, inhibitory or biphasic, effects on the spontaneous and evoked electrical activity of neurons in this region in rats and cats (3,7,31,33,34). In rats, sensory neurons within the medial hypothalamus are especially sensitive to the effects of direct GC administration (31).Complex bidirectional effects of GC are also observed in behavioral studies utilizing peripheral GC manipulations to examine the pharmacology of agonistic responding in rats, mice and hamsters (1 I , 16, 35). Systemic GC administration in intact animals, and GC replacement of adrenalectomized animals, can either increase aggressiv...

Arrival date and territorial behavior are associated with corticosterone metabolite levels in a migratory bird

“…It could be that the association of the history of CORT secretion as measured through CORT metabolites with territorial behavior registered 5 days later may have arisen due to a direct role of CORT on the promotion of aggressive behavior. In fact, studies in mammals have shown that glucocorticoids may have a direct regulatory role on the promotion of aggressive behaviors (Hayden-Hixson and Ferris 1991;Haller et al 1997;Mikics et al 2004Mikics et al , 2007.…”

“…It has also been reported that territorial aggression in birds causes a rapid increase in CORT levels, suggesting that this hormone may play a specific role in the regulation of territorial behavior (Landys et al 2007). In fact, studies on rodents indicate that glucocorticoids may act directly on the facilitation of aggressive behaviors (Hayden-Hixson and Ferris 1991;Haller et al 1997).…”

Optogenetically enhanced pituitary corticotroph cell activity post-stress onset causes rapid organizing effects on behaviour

“…Studies in mammals showed that injections of ACTH and related peptides can alter forms of avoidance 20 40 41 , stretching and yawning 42 , grooming 43 and sexually motivated actions 44 ; thus a role for pituitary peptides in regulating arousal has been suggested 45 . Evidence also shows that glucocorticoid administration can influence locomotion 22 46 , agonistic reactions 47 48 49 and courtship 23 50 51 . These studies relied on injections of exogenous hormones and behavioural measures of varying delays; rapid effects of endogenous effectors from the pituitary–adrenal unit have not been documented before.…”

High novelty-seeking predicts aggression and gene expression differences within defined serotonergic cell groups

“…These findings are consistent with other reports of increased corticosterone secretion following social encounters (File and Seth, 2003). While elevated corticosterone levels often correlate with aggression in rodents (Hayden-Hixson and Ferris, 1991) and humans (van Bokhoven et al, 2005), this relationship is complicated and the literature is not entirely in agreement (Summers and Winberg, 2006). This heterogeneity may represent inherent individual differences in emotionality, risk-taking, and impulsivity.…”