Hypothalamic histamine, growth rate, plasma prolactin and growth hormone levels in rats with long-term portacaval anastomosis

Objective and Design: Histamine can modulate feeding behaviour and hormone release, therefore we examined the hypothalamic histamine system, the growth pattern and the serum levels of prolactin and growth hormone in rats With portacaval anastomosis (PCA). Material: The growth rate of 30 PCA- and 30 sham-operated male Han:Wistar rats was monitored for 6 months. Thirteen sham and 9 PCA rats were used for biochemical studies. Methods: Histamine was assayed by HPLC, tele-methylhistamine by GC-MS, prolactin and growth hormone by RIA. Student's t-test was used to compare the groups. Results: Six months after surgery, the PCA rats exhibited marked growth retardation (weight gain of 20 g vs. 140 g for the sham rats; p < 0.001), increased plasma levels of prolactin (9.7 +/- 2.4 vs. 3.6 +/- 0.6; p < 0.01) and unaltered growth hormone levels (6.2 +/- 0.5 vs. 8.1 +/- 1.0). A six-fold elevation of histamine concentration (29.5 +/- 3,9 vs. 4.8 +/- 0.4, p < 0.001) and a two-fold increase of tele-methylhistamine levels (1.8 +/- 0.1 vs. 0.8 +/- 0.02; p < 0,001) were found in hypothalamus. Conclusion. We suggest that increased histaminergic activity in the hypothalamus may be involved in the development of growth retardation and in the enhanced basal secretion of prolactin in male rats with long-term PCA.