Somatostatin28(15-28), but not somatostatin28(1-12), affects central monoaminergic neurotransmission in rats.

The effects of intracerebroventricularly (icv) administered somatostatin28(SS28) fragments, SS28(1-12) and SS28(15-28), were investigated on central monoaminergic neurotransmission in rats. SS28(15-28) did not significantly influence the hypothalamic and striatal noradrenaline concentrations. In a dose-related manner, SS28(15-28) significantly increased the dopamine, dihydroxyphenyl acetic acid DOPAC), and serotonin concentrations in hypothalamus, but did not modify these measures in striatum. The other SS28 metabolite, SS28(1-12), had no statistically significant effects on the monoamine neurotransmission. SS28(15-28) (6 and 9 nmol) induced barrel rotation, while SS28(1-12) was ineffective following administration over a wide dose-range (3-18 nmol). In conclusion, SS28(15-28) influences the hypothalamic monoaminergic transmission and causes barrel rotation, whereas SS28(1-12) has no neurochemical or behavioural effects in these tests.