Spontaneous expression of inducible nitric oxide synthase in the hypothalamus and other brain regions of aging rats
Abstract
Our laboratory has demonstrated that aging in Brown-Norway rats is associated with decreased LH pulse amplitude and reduced GnRH and LH responsiveness to excitatory amino acids (EAA), presumably through the NMDA receptor (NMDAR). Nitric oxide (NO) is a neurotransmitter postulated to be involved in hypothalamic synaptic events required for normal GnRH regulation through the activation of neuronal nitric oxide synthase (nNOS). Paradoxically, excessive stimulation of nNOS by NMDAR or the expression of inducible nitric oxide synthase (iNOS) can lead to supraphysiological levels of NO acting as effector of apoptosis with resultant decreased regional neuronal function. The aims of this study were to determine: 1) whether aging in the preoptic area/medial basal hypothalamus is associated with altered NO synthesis; 2) the possible roles of the NMDAR/nNOS cascade and iNOS in this process; and 3) whether alterations in the levels of NOS isoforms are specific to this region of the brain. Brown Norway male rats (N = 5) at ages 1 (immature), 3 (adult), and 24 (old) months, were used for measuring NMDARs in hypothalamic membranes by the binding of a (3H)-NMDAR ligand. Another series of the same age groups of rats (N = 9) were used to determi...Continue Reading
Citations
Related Concepts
Related Feeds
Apoptosis
Apoptosis is a specific process that leads to programmed cell death through the activation of an evolutionary conserved intracellular pathway leading to pathognomic cellular changes distinct from cellular necrosis