Interleukin-1 stimulates the central release of corticotropin-releasing hormone in the primate.

The cytokine interleukin-1 (IL-1) is present in the brain and is known to cause a variety of neuroendocrine and immune effects in the rodent; the neuropeptide corticotropin-releasing hormone (CRH) plays a critical role in mediating many of these effects. Little is known about these neuropeptide interactions in the primate. We have therefore examined the effects of IL-1 alpha on the release of CRH in the ovariectomized rhesus monkey in vitro and in vivo. In 3 animals, the effect of IL-1 alpha on CRH release from the superfused hypothalamus was studied in vitro. The hypothalamus was divided in half and fragments from each half were superfused separately. Mean CRH release was 262 +/- (SE) 46 pg/20 min and increased to 1,340 +/- 470 pg/20 min after exposure to IL-1 alpha (p < 0.05). The effect of IL-1 alpha on CRH release into cerebrospinal fluid (CSF) in vivo was studied in 8 animals with chronic cannulas implanted in the lateral ventricle for IL-1 infusion; indwelling catheters were also placed via lumbar puncture and threaded into the cervical area for CSF collection. CSF was collected at a rate of 800 microliters/h during a 4-hour baseline period and for 4-8 h after intracerebroventricular infusion of 4.2 micrograms of IL-1 alpha. CRH increased significantly over time in CSF after IL-1 alpha infusion; the mean concentration of CRH increased from 83 +/- 17 pg/ml during the baseline period to 203 +/- 40 pg/ml after IL-1 alpha infusion (p < 0.01). We conclude that IL-1 stimulates central CRH release in the primate and that the effects of cytokines on the release of this important neuromodulator can be monitored in chronically cannulated animals in vivo.

Aromatization is not required for androgen induced changes in proopiomelanocortin gene expression in the hypothalamus.

Testosterone regulation of POMC mRNA and peptide levels has been previously demonstrated in the medial basal hypothalamus (MBH) of the rat. Although both dihydrotestosterone (DHT) and estradiol are known to affect POMC peptide levels in the MBH, it is unclear if the effects of testosterone on POMC gene expression are due to conversion by aromatization to estradiol or due to independent androgen actions. We have therefore compared the effects of the nonaromatizable androgen DHT and estradiol on POMC gene expression and beta-endorphin (beta-EP) levels in the MBH of castrated male rats. We have also examined the effect of the dopamine agonist, pergolide, on POMC in the DHT and estradiol treated animals in light of previous studies in female rats. In the first study POMC mRNA in the MBH, as measured by a solution hybridization assay, was 0.85 +/- 0.07 pg/microgram RNA 3 weeks after castration and decreased to 0.64 +/- 0.07 pg and 0.65 +/- 0.07 pg in the DHT treated rats with and without pergolide (P < 0.05). In the second study the mean POMC mRNA concentration in the MBH was 0.95 +/- 0.10 pg/microgram RNA and decreased to 0.68 +/- 0.06 pg and 0.70 +/- 0.08 pg in the estradiol treated rats with and without pergolide (P < 0.05). In both studies significant changes in beta-EP peptide levels paralleled the changes in POMC mRNA levels. We conclude that both androgens and estrogens can affect POMC mRNA levels in the male rat.(ABSTRACT TRUNCATED AT 250 WORDS)