The effects of intracerebroventricularly injected corticotropin-releasing factor (CRF) on the central nervous system: behavioural and biochemical studies.

Intracerebroventricularly (ICV) administered corticotropin-releasing factor (CRF) produces behavioural activation in rats. The present study was designed to investigate the effects of ICV administered CRF on not only locomotor activity, but also the turnover rates of dopamine (DA) and norepinephrine (NE) in various discrete brain regions in rats. ICV administration of 1 microgram CRF produced a significant increase in locomotor activity, while ICV administration of 10 micrograms CRF caused slow stereotypy with prominent grooming. The 3,4-dihydroxyphenylacetic acid/DA ratio, e.g. DA utilization, was increased in the frontal cortex (FC), striatum, hippocampus (HIPP) and amygdala. DA utilization in the FC increased in a dose dependent manner, suggesting that the hyperactivity of the mesocortical DA system is relevant to the grooming response. The 3-methoxy-4-hydroxy-phenylglycol/NE ratio was increased in the FC and HIPP, indicating the involvement of the dorsal NE pathway in ICV CRF-induced behavioural changes in rats. These findings are discussed in connection with the hypothesis that CRF produces behavioural changes consistent with increasing emotionality, especially anxiety, and may serve as a neuroendocrine modulator of stress-enhanced behaviour.