PubMed Health⌕ Search

Biomedical subjects

A Altar

Publications and source records attributed to A Altar.

9 recordsLinked to original sources
PubMed1984

Sex-related differences in pineal gland N-acetyltransferase induction by d-amphetamine.

The activity of the rat pineal gland enzyme, N-acetyltransferase (NAT), was measured to determine if amphetamine stimulation of norepinephrine release from sympathetic fibers innervating the gland varies according to sex-dependent mechanisms. Pineal gland NAT activity was increased following amphetamine treatment to a greater extent and for a longer duration in adult female rats compared to male animals. The greater in vivo stimulation of adult female pineal gland NAT activity by the drug developed after puberty, depended upon intact gonads, and apparently was not due to sex differences in the amount of norepinephrine released by the drug from sympathetic nerves when tested under in vitro conditions. The in vivo sex dependent effects of amphetamine may be related to the lesser rate at which the drug is metabolized and/or excreted by female rats compared to males.

Acetyltransferases↗
PubMed1983

The crossed mesostriatal projection: neurochemistry and developmental response to lesion.

The projections of substantia nigra and ventral tegmental area (SN-VTA) neurons to either the ipsilateral or contralateral caudate-putamen (CP) were studied in intact and 6-hydroxydopamine-treated rats, using both retrograde transport of fluorescent dyes and measurements of dopamine concentration. After unilateral CP injections of nuclear yellow or granular blue in intact 6- or 30-day-old rats, approximately 1% of the retrogradely labeled cells were located in the contralateral SN-VTA. In 6- or 30-day-old rats which had been injected with 6-hydroxydopamine in the left lateral hypothalamic area (LHA) at 1 day of age, the extent of cell labeling of both the uncrossed projection in the right hemisphere and the crossed projection originating in the left SN-VTA was normal. However, the number of labeled cells of the uncrossed pathway of the left side and the crossed pathway originating in the right SN-VTA were markedly decreased by the lesion, indicating that the crossed nigrostriatal cells decussate before they reach the LHA. The 6-hydroxydopamine-induced decreases in SN-VTA labeling of both the crossed and uncrossed pathway closely matched the degree of dopamine depletion in the lesioned CP at 6 days of age and at 30 days of age. A partial recovery of both measures occurred between days 6 and 30. Thus, retrograde labeling of SN-VTA cells and at 30 days of age. A partial recovery of both measures occurred between days 6 and 30. Thus, retrograde labeling of SN-VTA cells with fluorescent dyes provided a quantitative measure of the dopaminergic innervation of the neostriatum in both the uncrossed and crossed pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Functional synaptogenesis and the rat pineal gland: a pharmacological investigation.

Pineal glands obtained from rats of different ages were incubated in vitro with drugs known to specifically alter pre- or postsynaptic noradrenergic neurotransmission to determine when during development nerve terminal or receptor mediated control of glandular N-acetyltransferase (NAT) activity might reach functional maturation. Basal daytime NAT activity measured in vitro was lowest in fetal rats, increased dramatically by the day of birth, peaked at 10 days postnatally, and subsequently declined to near adult levels by 25 days of age. Drugs (isoproterenol, norepinephrine, or propranolol) known to influence pineal gland NAT activity by acting directly on pinealocyte postsynaptic beta-noradrenoceptors produced comparable changes in enzyme activity at all ages studied, although larger doses of the receptor agonist were required in fetal animals to elevate NAT activity. In contrast, in vitro incubation with indirect acting drugs (amphetamine or 1-dopa) which require functional presynaptic nerve terminals to exert their pharmacological effects, failed to increase pineal gland NAT activity until early in postnatal life. Hence, postsynaptic beta-noradrenoceptors may function to control pineal gland NAT activity prior to the time when the presynaptic sympathetic neurons innervating the gland attain maturational status.

Acetyltransferases↗
PubMed1980

A chronic subcutaneous gastric cannula in adult rats.

The design and method of implantation for a chronic gastric cannula in adult rats is described which obviates the necessity of externalizing the peritoneal cavity or its contents. This procedure minimizes tissue damage, post-operative recovery time, and permits intragastric infusions without the oropharyngeal sensations present with nasopharyngeal gastric catheters.

Animals↗
PubMed1979

Diet, central nervous system, and aging.

A variety of morphological, structural, and chemical changes have been described in the central nervous systems of aging humans and animals. Brain size and volume decline during senescence, and the brain atrophy is accompanied by changes in the number, size, and ultrastructural characteristics of nerve and glial cells. Moreover, recent evidence suggests that the ability of central nervous system cells to communicate with one another via the release of neurotransmitter compounds might be impaired in the elderly. Nutritional factors may play important roles in the aging process of the central nervous system by influencing brain neurotransmission, or by accelerating or retarding geriatric changes in central nervous system structure.

Aged↗
PubMedDate not supplied

Development of the mammalian pineal gland.

The literature concerning the morphological, biochemical, and pharmacological development of the mammalian pineal gland is reviewed with an emphasis on the ontogeny of pineal innervation by noradrenergic neurons. Mature pineal responses to various pharmacological manipulations and the well-characterized rhythms in pineal biochemistry appear only after postnatal axogenesis of sympathetic neurons, synaptogenesis between sympathetic nerve terminals and pineal adrenergic receptors, and pineal nerve terminal synthesis, storage, and inactivation of catecholamine neurotransmitter. Since postsynaptic biochemical capacities for pineal enzymatic and endocrine function appear at a relatively early age, it is proposed that development of presynaptic inputs to the pineal is rate-limiting in the maturation of the pineal gland as a circadian neuroendocrine transducer. Because of this, the pineal gland is an excellent model for the functional development of noradrenergic inputs to selective target organs.

Acetylserotonin O-Methyltransferase↗