Table 2.

Effect of long-term administration of CRH on baseline (preinjection) levels of body temperature, hippocampal extracellular concentrations of 5-HT and 5-HIAA, free corticosterone, and behavioral activity on day 7 of treatment

	Intracerebroventricular vehicle	Intracerebroventricular CRH	Subcutaneous CRH
Body temperature (°C)	37.03  ± 0.05 (8)	37.26  ± 0.12 (8)	37.04 ± 0.07 (4)
5-HT (fmol/sample)	15.27  ± 1.41 (12)	16.33  ± 1.13 (11)	n.d.
5-HIAA (pmol/sample)	11.06  ± 0.60 (13)	10.76  ± 0.55 (11)	n.d.
Free corticosterone (μg/dl)	0.0065  ± 0.0016 (13)	0.075  ± 0.014 (12)*	n.d.
Behavioral activity (arbitrary units)	1.49  ± 0.07 (13)	1.58  ± 0.07 (12)	n.d.

CRH (1 μg · μl⁻¹ · hr⁻¹) was infused into rats either intracerebroventricularly or subcutaneously. Control animals were treated intracerebroventricularly with vehicle (1 μl/hr). Baseline body temperature (Protocol A) was measured on day 7 between 7:30 A.M. (lights on) and 11:30 A.M. (intraperitoneal injection). Baseline hippocampal extracellular levels of 5-HT and 5-HIAA, dialysate concentrations of corticosterone, and behavioral activity (Protocol B) were measured between 9 A.M. (start microdialysis experiment) and 11:30 A.M. (intraperitoneal injection). The number of rats in each experimental group is in parentheses. Data are mean ± SEM (for further details see Materials and Methods).

^*p < 0.05 compared with vehicle-treated rats (Student’s t test). n.d., Not determined.