Tachykinin neurokinin 3 receptor signaling in cholecystokinin-elicited release of oxytocin and vasopressin

Neurokinin 3 receptor (NK3R) signaling has an integral role in the stimulated oxytocin (OT) and vasopressin (VP) release in response to hyperosmolarity and hypotension. Peripheral injections of cholecystokinin (CCK) receptor agonists for the CCK-A (sulfated CCK-8) and CCK-B (nonsulfated CCK-8) receptors elicit an OT release in rat. It is unknown whether NK3R contributes to this endocrine response. Freely behaving male rats were administered an intraventricular pretreatment of 250 or 500 pmol of SB-222200, a specific NK3R antagonist, or 0.15 M NaCl before an intraperitoneal or intravenous injection of CCK-8 (nonsulfated or sulfated) or 0.15 M NaCl. Blood samples were taken before intraventricular treatment and 15 min after intraperitoneal or intravenous injection, and plasma samples were assayed for OT and VP concentration. Intraperitoneal injection of both nonsulfated and sulfated CCK-8 significantly increased plasma OT levels and had no effect on plasma VP levels. Intravenous injection of sulfated CCK-8 stimulated an increase in plasma OT levels and did not alter plasma VP levels. However, intravenous injection of nonsulfated CCK-8 stimulated a significant increase in plasma levels of both OT and VP. No other studies have demonstrated CCK-8-stimulated release of VP in rat. NK3R antagonist did not alter baseline levels of either hormone. However, pretreatment of NK3R antagonist significantly blocked the CCK-stimulated release of OT in all CCK treatment groups and blocked VP release in response to intravenous injection of nonsulfated CCK-8. Therefore, central NK3R signaling is required for OT and VP release in response to CCK administration.

Early Relapses in Primary CNS Lymphoma (PCNSL) without Intraventricular Treatment.

Background: A systemic and intraventricular polychemotherapy regimen (“Bonn protocol”) with deferred radiotherapy had resulted in durable responses in 75% of patients < 60 years with primary CNS lymphoma (PCNSL), but had been complicated by a high rate of Ommaya reservoir infections. Purpose: Here, efficacy and toxicity of this regimen but without intraventricular treatment was evaluated in PCNSL. Patients and Methods : From 08/03 to 11/05, 18 patients with PCNSL < 60 years (median age 53 years) were treated within a phase II trial with a high-dose methotrexate (MTX; cycles 1,2,4 and 5) and cytarabine (Ara-C; cycles 3 and 6) based systemic therapy including dexamethasone, vinca-alkaloids, ifosfamide and cyclophosphamide. Results: Study accrual was prematurely stopped in 11/05 due to a high rate of early relapses. Seventeen/18 patients were assessable for response: Nine (53%) achieved complete response (CR), two (12%) complete response/unconfirmed (CRu), two (12%) partial response (PR), four (24%) showed progressive disease (PD); in one treatment was stopped due to toxicity. Median follow-up is 23 months; Kaplan-Meier estimates for median response duration were ten months only in responding patients and for median time to treatment failure (TTF) eight months in the whole group; median overall survival (OS) has not yet been reached. Systemic toxicity was mainly hematologic. Conclusions: In patients < 60 years with PCNSL polychemotherapy without intraventricular treatment results in a high response rate, but is associated with early relapses in the majority of cases. This is in contrast to the results achieved with the same protocol but with inclusion of intraventricular treatment.

Necessity of Intraventricular Chemotherapy with the Modified Bonn Protocol in Primary CNS Lymphoma (PCNSL) Patients.

Background: Treatment of primary CNS lymphoma (PCNSL) with a combined systemic and intraventricular chemotherapy (Bonn protocol) has achieved an overall response rate (ORR) of 84% and long term complete remissions in a substantial fraction of patients younger than 60 years. Purpose: Due to a high infection rate of the Ommaya reservoir the question was addressed if intraventricular treatment is dispensable in this polychemotherapy protocol. Patients and Methods: Fifty patients with histologically confirmed PCNSL were enrolled onto a phase II-study evaluating chemotherapy without radiotherapy and without intraventricular treatment. A high-dose methotrexate (MTX) (cycles 1,2,4,5) and cytarabine (ara-C) (cycles 3,6) based systemic therapy (including dexamethasone, vinca-alkaloids, ifosfamide and cyclophosphamide) was administered. Results: In an ongoing trial thirty-five of 50 patients (18 pat. < 60 years, 17 pat. over 60 years) are yet assessable for response after a median follow up of nine months (range: 1 to 26 months). In 18 patients < 60 years, the ORR was 78%. However, median time to treatment failure (TTF) was eight months, and median progression free survival (PFS) only 7 months according to frequent early relapses. Conclusions: Early relapses are frequent in younger patients treated with the modified Bonn protocol without intraventricular treatment despite a high ORR. These preliminary results support the assumption that intraventricular treatment is essential to achieve sustained remissions after successful treatment of PCNSL.