Peripheral oxytocin treatment modulates central dopamine transmission in the mouse limbic structures

The effects of subcutaneous (s.c.) oxytocin treatment have been investigated on various parameters of dopaminergic neurotransmission in basal forebrain structures (nucleus olfactorius posterior + nucleus accumbens + septum) of the mouse. Acute oxytocin treatment failed to influence dopamine utilization in the basal forebrain. Following chronic injections of oxytocin (0.2 mg/kg) for 8 8 days, the neuropeptide decreased dopamine utilization. Neither in vivo nor in vitro oxytocin treatment was capable of influencing the in vitro uptake of [(3)H]dopamine in basal forebrain slices. The spontaneous release of [(3)H]dopamine (in the presence of 4.2 mM K(+)) from basal forebrain tissue slices was not affected by in vitro or acute or chronic in vivo oxytocin treatment. The stimulated release of [(3)H]dopamine (in the presence of 30 mM K(+)) was significantly inhibited by chronic in vivo oxytocin administration. Chronic oxytocin treatment decreased the B(max) value of [(3)H]spiroperidol binding in the basal forebrain. The dissociation constant (K(d)) of [(3)H]spiroperidol binding was not influenced by oxytocin. The data indicate that peripheral oxytocin treatment is capable of modifying dopaminergic neurotransmission in mouse basal forebrain regions.