Differential peptidomics assessment of strain and age differences in mice in response to acute cocaine administration

Abstract

Neurochemical differences in the hypothalamic-pituitary axis between individuals and between ages may contribute to differential susceptibility to cocaine abuse. This study measured peptide levels in the pituitary gland (Pit) and lateral hypothalamus (LH) in adolescent (age 30 days) and adult (age 65 days) mice from four standard inbred strains, FVB/NJ, DBA/2J, C57BL/6J, and BALB/cByJ, which have previously been characterized for acute locomotor responses to cocaine. Individual peptide profiles were analyzed using mass spectrometric profiling and principal component analysis (PCA). Sequences of assigned peptides were verified by tandem mass spectrometry. PCA classified all strains according to their distinct peptide profiles in Pit samples from adolescent mice, but not adults. Select proopiomelanocortin (POMC)-derived peptides were significantly higher in adolescent BALB/cByJ and DBA/2J mice than in FVB/NJ or C57BL/6J mice. A subset of peptides in the LH, but not in the Pit, was altered by cocaine in adolescents. A 15 mg/kg dose of cocaine induced greater peptide alterations than a 30 mg/kg dose, particularly in FVB/NJ animals, with larger differences in adolescents than adults. Neuropeptides in the LH affected by acute cocaine administration included POMC-, myelin basic protein-, and glutamate transporter-derived peptides. The observed peptide differences could contribute to differential behavioral sensitivity to cocaine among strains and ages.

ProSAAS‐derived peptides are regulated by cocaine and are required for sensitization to the locomotor effects of cocaine

“…) or a very small number of neuropeptides (Romanova et al . ) were detected. Neither of these two studies from Romanova and colleagues used heat‐stabilization of the brain tissue prior to peptide extraction, and without this treatment it is difficult to detect neuropeptides over the high background level of intracellular peptides (Svensson et al .…”

Involvement of Activated Brain Stress Responsive Systems in Excessive and “Relapse” Alcohol Drinking in Rodent Models: Implications for Therapeutics

“…In the brain, the arcuate nucleus of the hypothalamus processes POMC to produce the potent opioid peptide β-endorphin, and α-, β-, and γ-melanocortins [Ragavan et al, 1983;Rubinstein et al, 1996;Cowley et al, 2001;Romanova et al, 2015]. Besides the arcuate nucleus, POMC mRNA molecule has also been detected in several other mouse and rat brain regions, including the NAc, amygdala, hippocampus and cerebral cortex, in much lower levels than those in the arcuate nucleus [Civelli et al, 1982;Zhou et al, 1996Zhou et al, , 2013aLeriche et al, 2007;Bodnar, 2014;Granholm et al, 2017].…”

Improved identification and quantitation of mature endogenous peptides in the rodent hypothalamus using a rapid conductive sample heating system

“…In order to allow time for dissection, especially of defined small brain structures, without using heat treatments, options such as “precooling” the brain by perfusing cold saline into the organ before dissection, 36 injecting cold modified Gey’s buffer salt solution into the body cavity immediately after euthanasia, 36,64 or fast sample freezing are effective. Although these methods reduce postmortem analyte degradation and are useful when precise anatomical areas need to be isolated, they do not prevent degradation without the need for additional stabilization methods.…”

“…27,30–33 For example, experiments conducted by Stingl et al 21 and Segerström et al 34 demonstrated that heat stabilization effectively arrests the ex-viv o peptidase activity, thereby preserving the chemical sample composition as compared to samples from unstabilized tissues. Various means of heat stabilization, such as incubation in a hot water bath, 8,35,36 animal sacrifice by focused microwave irradiation (FMR), 26,29,37 microwaving of dissected tissue, 18 and laser-guided rapid conductive heating in a commercial device, the Denator Stabilizor T1 (ST1), 38,39 were previously investigated in a variety of neural and neuroendocrine tissues.…”