BMY 7378 is a α2C and α1D adrenergic receptors inhibitor (pKi= 6.54 and 8.2, respectively) and a mixed agonist and antagonist for 5-HT1A receptors.

Adrenergic α1 and α2 receptors are G protein-coupled receptors that are located in CNS and periphery. It plays a role in regulating neurotransmission, smooth muscle contraction and thermogegualtion. 5-HT receptor is a G-protein coupled receptor for 5-hydroxytryptamine (serotonin) that found in nerve systems. It also functions as receptor for various alkaloids and psychoactive substances.

BMY 7378 blocks the inhibition on forskolin-stimulated adenylate cyclase activity in rat hippocampus induced by the 5-HT1A agonist, 8-OHh-DPAT. [1] In rat spinal cord, BMY 7378 is a weak partial agonist at the hippocampal 5-HT1A receptors. [2] BMY 7378 is also the first α1D adrenergic receptors subtype selective ligand that has high affinity and had a clear pharmacological distinction between the α1B and α1D adrenergic receptors subtypes. [3] In ligand-binding assay, BMY 7378 displays a 10-fold selectivity for α2C adrenergic receptors over other α2 adrenergic receptors. [4]

BMY 7378 not only shows 5-HT1A antagonist activity in the rat behavioral experiments, but also exerts a marked decrease of 5-HT release in ventral hippocampus of the anaesthetized rat in a dose-dependent manner (0.01-1.0 mg/kg s.c.) [5]

References:
1.  Yocca FD, Hyslop DK, Smith DW et al. BMY 7378, a buspirone analog with high affinity, selectivity and low intrinsic activity at the 5-HT1A receptor in rat and guinea pig hippocampal membranes. Eur J Pharmacol. 1987 Jun 4;137(2-3):293-4.
2.  Zemlan FP, Zieleniewski-Murphy A, Maureen Murphy R et al BMY 7378: Partial agonist at spinal cord 5-HT(1A) receptors. Neurochem Int. 1990;16(4):515-22.
3.  Goetz AS, King HK, Ward SD et al. BMY 7378 is a selective antagonist of the D subtype of alpha 1-adrenoceptors. Eur J Pharmacol. 1995 Jan 16;272(2-3):R5-6.
4.  Cleary L, Murad K, Bexis S et al. The alpha (1D)-adrenoceptor antagonist BMY 7378 is also an alpha (2C)-adrenoceptor antagonist. Auton Autacoid Pharmacol. 2005 Oct;25(4):135-41.
5.  Sharp T, Backus LI, Hjorth S et al. Further investigation of the in vivo pharmacological properties of the putative 5-HT1A antagonist, BMY 7378. Eur J Pharmacol. 1990 Feb 13;176(3):331-40.