Enables glycerol-3-phosphate dehydrogenase [NAD+] activity. Acts upstream of or within several processes, including cellular response to cAMP; gluconeogenesis; and glycerophosphate shuttle. Located in mitochondrion. Is expressed in several structures, including alimentary system; genitourinary system; integumental system; liver; and nervous system. Orthologous to human GPD1 (glycerol-3-phosphate dehydrogenase 1). [provided by Alliance of Genome Resources, Apr 2022]